CN103095308B

CN103095308B - I/O interface circuit and comprise key scan device and the scan method of this circuit

Info

Publication number: CN103095308B
Application number: CN201210594660.8A
Authority: CN
Inventors: 郑尊标; 冯兵
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2012-12-31
Filing date: 2012-12-31
Publication date: 2015-07-29
Anticipated expiration: 2032-12-31
Also published as: CN103095308A

Abstract

The invention discloses a kind of I/O interface circuit, low-power consumption key scan device and method and low-power consumption dynamic keyboard scan method, described I/O interface circuit comprises output state control module, first input state control module and the second input state control module, output state control module comprises the first fixed level and the first switch element, first input state control module comprises the second fixed level, second switch unit and the second resistance unit, second input state control module is provided with the first resistance unit and the 3rd switch element, first fixed level is contrary with the second fixed level logic, first switch element, the control end of second switch unit and the 3rd switch element is connected with the on-off controller for control switch cell conduction or disconnection.Circuit of the present invention, apparatus and method, when I/O interface level switches, reduce the transient current produced in the input stage of himself, thus reduce power consumption, in turn ensure that the effective detection being connected to button on this I/O interface simultaneously.

Description

I/O interface circuit and comprise key scan device and the scan method of this circuit

Technical field

The present invention relates to keyboard interface and keyboard scanning technique field, particularly relate to a kind of I/O interface circuit, low-power consumption key scan device and method and low-power consumption dynamic keyboard scan method.

Background technology

Existing product is more and more stricter to the power consumption requirements of complete machine, and especially when complete machine is in holding state, keyboard is as the common components of complete machine man-machine interface, and its power consumption is the part in Overall Power Consumption, reduces keyboard power consumption particularly important.Keyboard is when key scan, button one end exports fixed level by button output, the key-press input end of the button other end provides an original levels contrary with the former by pullup or pulldown resistance, when there being button to press, the pullup or pulldown state of key-press input end is driven by contrary level, produce level saltus step, judge have button to produce thus.With reference to Fig. 1, for the button K01 ' in keyboard when scanning, the two ends of button K01 ' are connected to I/O interface P0 and I/O interface P1, I/O interface P0 is connected with metal-oxide-semiconductor MP0 ' by pull-up resistor R0 ', the drain electrode of metal-oxide-semiconductor MP0 ' is connected with pull-up resistor R0 ', and the source electrode of metal-oxide-semiconductor MP0 ' is connected with VDD, and the grid of metal-oxide-semiconductor MP0 ' is control end, I/O interface P0 is also connected with GND by metal-oxide-semiconductor MN0 ', and the grid of metal-oxide-semiconductor MN0 ' is control end; Corresponding, I/O interface P1 is also connected to metal-oxide-semiconductor MP1 ', pull-up resistor R1 ' and metal-oxide-semiconductor MN1 '.When single button detects, the two ends of button K01 ' need to be configured to the contrary level of logic, both configure I/O interface P0 and be in output low level state, I/O interface P1 is in band pull-up input state, also the state of I/O interface P1 and I/O interface P0 can be exchanged, when there being button to press, I/O interface P1 detects level saltus step, judge have button to produce, current trend when dotted portion is for button being detected in Fig. 1.

In key scan process, inevitable needs carry out switching between the input state of output state and band opposite levels pullup/pulldown at the I/O interface at button two ends, due to factors such as device package and external keyboard connections, each I/O interface there is parasitic capacitance to exist, the state of I/O interface is often carried out a level and is switched, be actually VDD by the charging process of pull-up resistor to I/O interface parasitic capacitance, or I/O interface parasitic capacitance is by the discharge process of pull down resistor to GND.General upper pull down resistor is larger, then charge and discharge process is longer, and level switches along more slow, and the electric current produced on the input stage cmos circuit of I/O interface is thus also larger, and power consumption is also higher.But contrary in order to effectively ensure the level logic at button two ends, it is too little that upper pull down resistor can not be arranged, and in order to reduce the time that I/O interface level switches, it is too large that upper pull down resistor can not be arranged.In order to ensure effective detection of button in prior art, cause the electric current on input stage cmos circuit comparatively large, make the power consumption of keyboard when button detects also higher.

Summary of the invention

Technical problem to be solved by this invention be for existing I/O interface circuit when being switched to input state by output state, I/O interface level state switches slowly, I/O interface input stage electric current is large, when causing standby, I/O Interface status switches the high problem of power consumption, provides a kind of I/O interface level switches rapidly, I/O interface input stage electric current is little I/O interface circuit, low-power consumption key scan device, low-power consumption key scanning method and low-power consumption dynamic keyboard scan method.

For solving the problem, a kind of technical scheme of the present invention is:

A kind of I/O interface circuit, comprise the output state control module and the first input state control module that are connected with I/O interface, output state control module comprises the first fixed level and the first switch element that are connected in turn, the other end of the first switch element is connected with I/O interface, first input state control module comprises the second fixed level be connected in turn, second switch unit and the second resistance unit, the other end of the second resistance unit is connected with I/O interface, the control end of the first switch element and second switch unit is connected with the on-off controller for control switch cell conduction or disconnection, first fixed level is contrary with the second fixed level logic, described I/O interface circuit is also connected with the second input state control module, second input state control module is provided with the first resistance unit for shortening I/O interface level switching time and the 3rd switch element, second fixed level, 3rd switch element is connected in turn with the first resistance unit, the other end of the first resistance unit is connected with I/O interface, the control end of the 3rd switch element is connected with on-off controller, on-off controller exports the conducting state that control information controls the first switch element, second switch unit and the 3rd switch element, and to configure the I/O interface be connected with the first switch element place module of conducting be respectively output first fixed level state, the I/O interface be connected with the second switch unit place module of conducting is the first input state, and the I/O interface be connected with the 3rd switch element place module of conducting is the second input state, described on-off controller at least comprises one group of control information, makes the I/O interface configuration being in output first fixed level state be the second input state, when described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, then the first fixed level is low level, second fixed level is high level, described first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is output low level state, first input state is band weak pull-up input state, and the second input state is band strong pull-up input state, when described I/O interface circuit is the drop-down I/O interface circuit of built-in pull-down structure, then the first fixed level is high level, second fixed level is low level, described first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is for exporting high level state, first input state is band weak pull-down input state, and the second input state is band strong pull-down input state, when described I/O interface circuit is the upper drop-down I/O interface circuit of built-in upper pull-up structure and pull-down structure simultaneously, upper drop-down I/O interface circuit comprises two groups of I/O interface circuits, is respectively pull-up I/O interface circuit and drop-down I/O interface circuit, first fixed level of described pull-up I/O interface circuit is low level, second fixed level is high level, first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is output low level state, and the first input state is band weak pull-up input state, and the second input state is band strong pull-up input state, first fixed level of described drop-down I/O interface circuit is high level, second fixed level is low level, first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is for exporting high level state, and the first input state is band weak pull-down input state, and the second input state is band strong pull-down input state.

I/O interface circuit of the present invention is by controlling the access state of output state control module, the first input state control module and the second input state control module and I/O interface, be configured with the state of three kinds of I/O interfaces, be respectively output first fixed level state, the first input state and the second input state.Under the control of on-off controller, when the first switching means conductive in output state control module, then the first fixed level access I/O interface, now I/O interface is in output first fixed level state; Second switch cell conduction in the first input state control module, then the second fixed level and the second resistance unit access I/O interface, now I/O interface is in the first input state; When the 3rd switching means conductive in the second input state control module, then the second fixed level and the first resistance unit access I/O interface, now I/O interface is in the second input state.Under the configuration of control signal, I/O interface can switch as required in three kinds of states, and I/O interface circuit of the present invention is applicable to the key scan of various structure keyboard.

Wherein, the first input state and the first fixed level state of output are used for effective button and detect when button detects, therefore the resistance of the second resistance unit can not be too little, make the level logic of the first input state and the first fixed level state of output contrary.On-off controller comprises one group of control information, makes the I/O interface configuration being in output first fixed level state be the second input state, and the second input state is used for when I/O Interface status switches; Make the first resistance unit access I/O interface, the first less resistance unit resistance is set, discharging current when I/O interface level switches can be increased, reduce discharge time now, the state of I/O interface is switched fast, in order to reduce the transient current of I/O interface input stage cmos circuit, and then reduce the power consumption of I/O interface circuit.

Be compared to prior art, the second input state control module set up by I/O interface circuit of the present invention, I/O interface is made to have the second input state for shortening I/O interface level switching time, configuration I/O is switched to the second input state by exporting the first fixed level state when interface level switches, when I/O interface level switches, for each I/O interface from outputting to input handoff procedure, be reduced the transient current produced in the input stage of himself, thus reduce power consumption, and when button detects, then adopt the first input state ensure that to be connected to effective detection of button on this I/O interface.

Preferably, when described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, described first fixed level is GND, second fixed level is VDD, first switch element is the first metal-oxide-semiconductor, and second switch unit is the 3rd metal-oxide-semiconductor, and the 3rd switch element is the second metal-oxide-semiconductor; Second metal-oxide-semiconductor is all connected with VDD with the source electrode of the 3rd metal-oxide-semiconductor, the source electrode of the first metal-oxide-semiconductor is connected with GND, second metal-oxide-semiconductor is connected with weak pull-up resistance with strong pull-up resistance respectively with the drain electrode of the 3rd metal-oxide-semiconductor, strong pull-up resistance is connected with the drain electrode of the first metal-oxide-semiconductor with the other end of weak pull-up resistance, the drain electrode of the first metal-oxide-semiconductor is the input of I/O interface, and the first metal-oxide-semiconductor, the second metal-oxide-semiconductor are all connected with on-off controller with the grid of the 3rd metal-oxide-semiconductor.

Preferably, when described I/O interface circuit is the drop-down I/O interface circuit of built-in pull-down structure, described first fixed level is VDD, second fixed level is GND, first switch element is the 4th metal-oxide-semiconductor, and second switch unit is the 6th metal-oxide-semiconductor, and the 3rd switch element is the 5th metal-oxide-semiconductor; 5th metal-oxide-semiconductor is all connected with GND with the source electrode of the 6th metal-oxide-semiconductor, the source electrode of the 4th metal-oxide-semiconductor is connected with VDD, 5th metal-oxide-semiconductor is connected with weak pull-down resistance with strong pull-down resistance respectively with the drain electrode of the 6th metal-oxide-semiconductor, strong pull-down resistance is connected with the drain electrode of the 4th metal-oxide-semiconductor with the other end of weak pull-down resistance, the drain electrode of the 4th metal-oxide-semiconductor is the input of I/O interface, and the 4th metal-oxide-semiconductor, the 5th metal-oxide-semiconductor are connected with on-off controller with the grid of the 6th metal-oxide-semiconductor.

Preferably, when described I/O interface circuit is the upper drop-down I/O interface circuit of built-in upper pull-up structure and pull-down structure simultaneously, first fixed level of described pull-up I/O interface circuit, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively GND, VDD, 13 metal-oxide-semiconductor, 16 metal-oxide-semiconductor, 18 metal-oxide-semiconductor, weak pull-up resistance and strong pull-up resistance, first fixed level of drop-down I/O interface, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively VDD, GND, 14 metal-oxide-semiconductor, 15 metal-oxide-semiconductor, 17 metal-oxide-semiconductor, weak pull-down resistance and strong pull-down resistance, 13 metal-oxide-semiconductor, 15 metal-oxide-semiconductor is all connected with GND with the source electrode of the 17 metal-oxide-semiconductor, 14 metal-oxide-semiconductor, 16 metal-oxide-semiconductor is all connected with VDD with the source electrode of the 18 metal-oxide-semiconductor, the drain electrode of the 18 metal-oxide-semiconductor is connected by the drain electrode of strong pull-up resistance with the 14 metal-oxide-semiconductor, the drain electrode of the 16 metal-oxide-semiconductor is connected by the drain electrode of weak pull-up resistance with the 14 metal-oxide-semiconductor, the drain electrode of the 17 metal-oxide-semiconductor is connected by the drain electrode of strong pull-down resistance with the 13 metal-oxide-semiconductor, the drain electrode of the 15 metal-oxide-semiconductor is connected by the drain electrode of weak pull-down resistance with the 13 metal-oxide-semiconductor, the drain electrode of the 13 metal-oxide-semiconductor is connected with the drain electrode of the 14 metal-oxide-semiconductor, the drain electrode of the 13 metal-oxide-semiconductor is the input of I/O interface, 13 metal-oxide-semiconductor, 14 metal-oxide-semiconductor, 15 metal-oxide-semiconductor, 16 metal-oxide-semiconductor, 17 metal-oxide-semiconductor is all connected with on-off controller with the grid of the 18 metal-oxide-semiconductor.

Preferably, the Standard resistance range of described strong pull-up resistance is 5K-50K, and the Standard resistance range of weak pull-up resistance is 50K-500K.

Preferably, the Standard resistance range of described strong pull-down resistance is 5K-50K, and the Standard resistance range of weak pull-down resistance is 50K-500K.

Preferably, the Standard resistance range of described strong pull-up resistance and strong pull-down resistance is 5K-50K, and the Standard resistance range of weak pull-up resistance and weak pull-down resistance is 50K-500K.

I/O interface circuit can be the one in pull-up I/O interface circuit, drop-down I/O interface circuit and upper drop-down I/O interface circuit, and the I/O interface circuit of three kinds of structures includes output first fixed level state, the first input state and the second input state.Strong pull-up resistance or the strong pull-down resistance of Standard resistance range 5K-50K is adopted in I/O interface circuit, Standard resistance range is weak pull-up resistance and the weak pull-down resistance of 50K-500K, the strong pull-up resistance of different resistance or strong pull-down resistance, the electric current that the input stage cmos circuit of corresponding I/O interface produces is also different.When I/O interface is switched to the second input state by the first fixed level state that exports, because the upper pull down resistor of access I/O interface is less, charge or discharge electric current is larger, the charge or discharge process of I/O interface to parasitic capacitance is shorter, the switch speed of level is also rapid, and the electric current produced on the input stage cmos circuit of I/O interface is thus also less.

Another kind of technical scheme of the present invention is:

A kind of low-power consumption key scan device, described scanning means is at least connected with a button, and the two ends of described button are connected to I/O interface circuit of the present invention.

Another technical scheme of the present invention is:

A kind of low-power consumption key scanning method, the realization of described scan method, based on low-power consumption key scan device, comprises the steps:

The scan period of a) presetting scanning monitor and the control signal switched for I/O Interface status;

B) scanning monitor exports the state that control signal configures all I/O interfaces, carries out periodic scan and perform button detecting the I/O interface of button:

B1. configure any one I/O interface and be in output first fixed level state, other all I/O interface is in the first input state, detects the I/O interface being in the first input state, if the saltus step of level detected, then represent that button is pressed, otherwise enter step b2;

B2. configuration is in the I/O interface of output first fixed level state is the second input state, if all buttons are all scanned, then enters step b3, otherwise returns step b2 continuation detection;

B3. configure all I/O interfaces and be in the first input state, return step b1 according to the scan period of scanning monitor and restart to detect.

Low-power consumption key scan device and method of the present invention is used for the scanning of single button, multiple button and matrix press-key, and the switching with I/O interface level is rapid, feature low in energy consumption.The scanning monitor adopted in the present invention can replace breaker in middle controller of the present invention, controls the conducting state of the first switch element, second switch unit and the 3rd switch element in order to export control information.

4th kind of technical scheme of the present invention is:

A kind of low-power consumption dynamic keyboard scan method, the realization of described scan method, based on the pull-up I/O interface circuit in the present invention, comprises the steps:

A) keyboard configuration is become to have the stepped keyboard of N number of I/O interface, between any two I/O interfaces, connect a button, any one I/O interface is connected with GND by a button;

B) state arranging I/O interface is three kinds, is respectively output low level state, band strong pull-up input state and band weak pull-up input state;

The scan period of c) presetting scanning monitor and the control signal switched for I/O Interface status;

D) scanning monitor configures the state of all I/O interfaces by control signal, carries out periodic scan and perform button detecting the I/O interface of keyboard:

D1. configure all I/O interfaces and be in band weak pull-up input state, scan the incoming level of all I/O interfaces, if the level saltus step of I/O interface detected, then output key detection signal, otherwise enter steps d 2;

D2. configure any one I/O interface and be in output low level state, other all I/O interface is in band weak pull-up input state, scan all I/O interfaces being in band weak pull-up input state, if the level saltus step of above-mentioned any I/O interface detected, then output key detection signal, otherwise enter steps d 3;

D3. be in the I/O interface of output low level state in configuration step d2 for band strong pull-up input state, other all I/O interface is band weak pull-up input state; If all I/O interfaces are all scanned, then enter steps d 4, otherwise return steps d 2 continuation scanning;

D4. configure all I/O interfaces and be in band weak pull-up input state, stop key detection, returns steps d 1 restart scanning according to the scan period of scanning monitor.

5th kind of technical scheme of the present invention is:

A kind of low-power consumption dynamic keyboard scan method, the realization of described scan method, based on the drop-down I/O interface circuit in the present invention, comprises the steps:

A) keyboard configuration is become to have the stepped keyboard of N number of I/O interface, between any two I/O interfaces, connect a button, any one I/O interface is connected with VDD by a button;

B) state arranging I/O interface is three kinds, is respectively and exports high level state, band strong pull-down input state and band weak pull-down input state;

D1. configure all I/O interfaces and be in band weak pull-down input state, scan the incoming level of all I/O interfaces, if the level saltus step of I/O interface detected, then output key detection signal, otherwise enter steps d 2;

D2. configure any one I/O interface and be in defeated high level state, other all I/O interface is in band weak pull-down input state, scan all I/O interfaces being in band weak pull-down input state, if the level saltus step of above-mentioned any I/O interface detected, then output key detection signal, otherwise enter steps d 3;

D3. being in the I/O interface exporting high level state in configuration step d2 is band strong pull-down input state, and other all I/O interface is band weak pull-down input state; If all I/O interfaces are all scanned, then enter steps d 4, otherwise return steps d 2 continuation scanning;

D4. configure all I/O interfaces and be in band weak pull-down input state, stop key detection, returns steps d 1 restart scanning according to the scan period of scanning monitor.

The scanning monitor adopted in the present invention can replace breaker in middle controller of the present invention, the conducting state of the first switch element, second switch unit and the 3rd switch element is controlled in order to export control information, make pull-up I/O interface circuit have output low level state, band strong pull-up input state and band weak pull-up input state, drop-down I/O interface circuit is had and exports high level state, band strong pull-down input state and band weak pull-down input state.Two kinds of low-power consumption keyboard scanning methods based on pull-up I/O interface circuit and drop-down I/O interface circuit of the present invention mainly for having N number of I/O interface, the dynamic keyboard of N* (N+1)/2 button scans.In the scanning process of keyboard, add the input state of strong pull-up/strong pull-down, in the process that I/O interface is switched to input state by output state, add the step that is first switched to strong pull-up/strong pull-down input state.Be specially, steps d 1, first scanning and all buttons be connected between I/O interface and the first fixed level; Steps d 2, scans the button be connected between certain I/O interface being in output state and other I/O interfaces all; Steps d 3, level switching is carried out to the I/O interface being in output state, the I/O interface being in output state is made only to switch to band strong pull-up input state or band strong pull-down input state, simultaneously, scanning monitor detects all I/O interfaces and whether was all configured above-mentioned steps, guarantees that all buttons are all scanned; Steps d 4, configuring all I/O interfaces is initial input state, for the scanning of next cycle is ready.Wherein the scan period can be arranged according to scanning needs, and generally within 50ms, the cycle of steps d 4, generally in 0-20ms, for ensureing that effective button detects, avoids the situation of Lou key to occur.In steps d 3 of the present invention, make the state of I/O interface have switching low to high or from high to low short as much as possible, reduce the transient current of the input stage in handoff procedure.Make keyboard without under key-case, for each I/O interface from outputting to input handoff procedure, being reduced the electric current produced in the input stage of himself, thus reducing power consumption.For ensureing that effective button detects, the present invention, in scanning process, all adopts the weak up/down of band to draw input state to carry out.

Be compared to prior art, in the process that low-power consumption dynamic keyboard scan method of the present invention is switched to input state by output state at I/O interface, add the input state of band strong pull-up/strong pull-down, compare traditional switch step and add the input state that is first switched to band strong pull-up/strong pull-down, and when button detects, be only limitted to use band weak pull-up/weak pull-down input state.Both take into account effective detection of button, again reduce the electric current in scanning process.

Accompanying drawing explanation

Fig. 1 is the circuit theory diagrams that in prior art, keyboard detects.

Fig. 2 is the schematic block circuit diagram of I/O interface circuit of the present invention.

Fig. 3 is the schematic block circuit diagram of low-power consumption key scan device of the present invention.

Fig. 4 is the pull-up I/O interface circuit schematic diagram of I/O interface circuit embodiment one of the present invention.

Fig. 5 is the drop-down I/O interface circuit schematic diagram of I/O interface circuit embodiment two of the present invention.

Fig. 6 is the pull-up I/O interface circuit schematic diagram of I/O interface circuit embodiment three of the present invention.

Fig. 7 is the drop-down I/O interface circuit schematic diagram of I/O interface circuit embodiment four of the present invention.

Fig. 8 is the keyboard circuit schematic diagram be connected with pull-up I/O interface in low-power consumption dynamic keyboard scan method of the present invention.

Fig. 9 is the keyboard circuit schematic diagram be connected with drop-down I/O interface in low-power consumption dynamic keyboard scan method of the present invention.

Figure 10 is the level change sequential chart of pull-up I/O interface in each step in low-power consumption dynamic keyboard scan method of the present invention.

Figure 11 is the comparison diagram that in low-power consumption dynamic keyboard scan method of the present invention, pull-up I/O interface is switched to switching sequence in the sequential of input state and prior art by output state.

Figure 12 is the upper drop-down I/O interface circuit schematic diagram of low-power consumption dynamic keyboard scanning means embodiment five of the present invention.

Figure 13 is the upper drop-down I/O interface circuit schematic diagram of low-power consumption dynamic keyboard scanning means embodiment six of the present invention.

Figure 14 is the keyboard circuit schematic diagram be connected with upper drop-down I/O interface in low-power consumption dynamic keyboard scan method of the present invention.

Embodiment

Further describe the present invention below in conjunction with drawings and Examples, but protection scope of the present invention is not limited to this.

With reference to Fig. 2, I/O interface circuit of the present invention, comprises the output state control module, the first input state control module and the second input state control module that are connected with I/O interface.Output state control module comprises the first fixed level and the first switch element that are connected in turn, and the other end of the first switch element is connected with I/O interface; First input state control module comprises the second fixed level, second switch unit and the second resistance unit that are connected in turn, and the other end of the second resistance unit is connected with I/O interface; Second input state control module is provided with the first resistance unit for shortening I/O interface level switching time and the 3rd switch element, second fixed level, the 3rd switch element are connected in turn with the first resistance unit, and the other end of the first resistance unit is connected with I/O interface.

First switch element, the control end of second switch unit and the 3rd switch element is connected with the on-off controller for control switch cell conduction or disconnection, first fixed level is contrary with the second fixed level logic, on-off controller exports control information and controls the first switch element, the conducting state of second switch unit and the 3rd switch element, by controlling output state control module, the access state of the first input state control module and the second input state control module and I/O interface, be configured with the state of three kinds of I/O interfaces, be respectively output first fixed level state, first input state and the second input state.Under the control of on-off controller, when the first switching means conductive in output state control module, then the first fixed level access I/O interface, now I/O interface is in output first fixed level state; Second switch cell conduction in the first input state control module, then the second fixed level and the second resistance unit access I/O interface, now I/O interface is in the first input state; When the 3rd switching means conductive in the second input state control module, then the second fixed level and the first resistance unit access I/O interface, now I/O interface is in the second input state.Under the configuration of control signal, I/O interface can switch as required in three kinds of states, and I/O interface circuit of the present invention is applicable to the key scan of various structure keyboard.

Wherein, the first input state and the first fixed level state of output are used for effective button and detect when button detects, therefore the resistance of the second resistance unit can not be too little, make the level logic of the first input state and the first fixed level state of output contrary.On-off controller comprises one group of control information, makes the I/O interface configuration being in output first fixed level state be the second input state, and the second input state is used for when I/O Interface status switches; By the first resistance unit access for shortening I/O interface level switching time, the first less resistance unit resistance is set, discharging current when I/O interface level switches can be increased, reduce discharge time now, the state of I/O interface is switched fast, in order to reduce the transient current of I/O interface input stage cmos circuit, and then reduce the power consumption of I/O interface circuit.

I/O interface circuit can be the one in pull-up I/O interface circuit, drop-down I/O interface circuit and upper drop-down I/O interface circuit, and the I/O interface circuit of three kinds of structures includes output first fixed level state, the first input state and the second input state.

Described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, then the first fixed level is low level, second fixed level is high level, described first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, the Standard resistance range of strong pull-up resistance is 5K-50K, the Standard resistance range of weak pull-up resistance is 50K-500K, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is output low level state, first input state is band weak pull-up input state, second input state is band strong pull-up input state.

Described I/O interface circuit is the drop-down I/O interface circuit of built-in pull-down structure, then the first fixed level is high level, second fixed level is low level, described first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, the Standard resistance range of strong pull-down resistance is 5K-50K, the Standard resistance range of weak pull-down resistance is 50K-500K, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is for exporting high level state, first input state is band weak pull-down input state, second input state is band strong pull-down input state.

Described I/O interface circuit is the upper drop-down I/O interface circuit of built-in upper pull-up structure and pull-down structure simultaneously, and upper drop-down I/O interface circuit comprises two groups of I/O interface circuits, is respectively pull-up I/O interface circuit and drop-down I/O interface circuit; First fixed level of described pull-up I/O interface circuit is low level, second fixed level is high level, first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is output low level state, and the first input state is band weak pull-up input state, and the second input state is band strong pull-up input state; First fixed level of described drop-down I/O interface circuit is high level, second fixed level is low level, first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is for exporting high level state, and the first input state is band weak pull-down input state, and the second input state is band strong pull-down input state; The Standard resistance range of described strong pull-up resistance and strong pull-down resistance is 5K-50K, and the Standard resistance range of weak pull-up resistance and weak pull-down resistance is 50K-500K.

With reference to Fig. 3, low-power consumption key scan device of the present invention, described scanning means is at least connected with a button, and the two ends of button are connected to I/O interface circuit.Lift a specific embodiment to be below described low-power consumption key scan device of the present invention, and describe scanning process in detail by low-power consumption key scanning method.Scanning means is only connected with button K01, the I/O interface circuit that definition is connected to button K01 two ends is respectively an I/O interface circuit and the 2nd I/O interface circuit, and the I/O interface be connected with the 2nd I/O interface circuit with an I/O interface circuit is an I/O interface and the 2nd I/O interface.

When button K01 detects, comprise the steps:

B1. any one configuration in an I/O interface and the 2nd I/O interface is in output first fixed level state, other I/O interface is in the first input state, detect the I/O interface being in the first input state, if the saltus step of level detected, then represent that button K01 is pressed, otherwise enter step b2;

Wherein, the I/O interface circuit being connected to button two ends can be pull-up I/O interface circuit or drop-down I/O interface circuit, if pull-up I/O interface circuit, the first fixed level state that then exports is output low level state, first input state is band weak pull-up input state, and the second input state is band strong pull-up input state; If drop-down I/O interface circuit, then the first fixed level state that exports is for exporting high level state, and the first input state is band weak pull-down input state, and the second input state is band strong pull-down input state.Low-power consumption key scan device and method of the present invention is used for the scanning of single button, multiple button and matrix press-key, for the scanning means of multiple button and matrix press-key and method with reference to above-mentioned detecting step.

Describe I/O interface circuit of the present invention in detail below by embodiment one, embodiment two, embodiment three and embodiment four and realize low-power consumption dynamic scan method based on above-mentioned I/O interface circuit, making I/O interface can be configured at least one output state and at least two kinds of input states by control signal.In order to know the existence of detailed description parasitic capacitance, in an embodiment the parasitic capacitance that above-mentioned factor etc. produces being equivalent to parasitic capacitance C0 in statement, in each view, being labeled as C0.Therefore, I/O interface is connected with an a parasitic capacitance C0 and input stage buffer CM, and I/O interface is for connecting keyboard and scanning monitor.Describe another kind of I/O interface circuit of the present invention and its scan method in detail by embodiment five and embodiment six simultaneously, make I/O interface can be configured to output low level state, band strong pull-up input state, band weak pull-up input state, be exported high level state, band strong pull-down input state and band weak pull-down input state six kinds by control signal, wherein equivalent parasitic capacitances is labeled as C0 and C1 respectively in each view, and input stage buffer flag is CM.Embodiment one, embodiment two, embodiment three, embodiment four, embodiment five and embodiment six are only the representative example of the present invention, realize three kinds of states in the present invention or six kinds of states all within protection scope of the present invention arbitrarily by some up/down pull-up resistors and some metal-oxide-semiconductors.

Embodiment one:

With reference to Fig. 4, described pull-up I/O interface is connected with output state control module, the first input state control module and the second input state control module, output state control module is provided with the first fixed level and the first switch element, first input state control module comprises the second fixed level, second switch unit and the second resistance unit, and the second input state control module is provided with the first resistance unit and the 3rd switch element.First fixed level is GND, and the second fixed level is VDD, and the first switch element is the first metal-oxide-semiconductor MN0, second switch unit is the 3rd metal-oxide-semiconductor MP0,3rd switch element is the second metal-oxide-semiconductor MP1, and the second resistance unit is weak pull-up resistance R2, and the first resistance unit is strong pull-up resistance R1.

The source electrode of the second metal-oxide-semiconductor MP1 and the 3rd metal-oxide-semiconductor MP0 is all connected with VDD, the source electrode of the first metal-oxide-semiconductor MN0 is connected with GND, the drain electrode of the second metal-oxide-semiconductor MP1 and the 3rd metal-oxide-semiconductor MP0 is connected to strong pull-up resistance R1 and weak pull-up resistance R2, strong pull-up resistance R1 is connected with the drain electrode of the first metal-oxide-semiconductor MN0 with the other end of weak pull-up resistance R2, the drain electrode of the first metal-oxide-semiconductor MN0 is the input of I/O interface, for connecting keyboard, the first metal-oxide-semiconductor MN0, the second metal-oxide-semiconductor MP1 are connected with scanning monitor with the grid of the 3rd metal-oxide-semiconductor MP0.Wherein, the second metal-oxide-semiconductor MP1 and the 3rd metal-oxide-semiconductor MP0 is PMOS, and the first metal-oxide-semiconductor MN0 is NMOS tube, and the resistance of strong pull-up resistance R1 is the resistance of 5k and weak pull-up resistance R2 is 150k.

The grid level of the first metal-oxide-semiconductor MN0, the second metal-oxide-semiconductor MP1 and the 3rd metal-oxide-semiconductor MP0 is labeled as S1, S2 and S3 in the diagram respectively, and on-off controller is by the level of a group of control signal configuration S1, S2 and S3.When S1, S2 and S3 are high level, pull-up I/O interface is in output low level state; When S1, S2 are low level, when S3 is arbitrary value, pull-up I/O interface is in band strong pull-up input state; When S1 be low level, S2 be high level and S3 be low level time, pull-up I/O interface is in band weak pull-up input state.

Embodiment two:

With reference to Fig. 5, described drop-down I/O interface is connected with output state control module, the first input state control module and the second input state control module, output state control module is provided with the first fixed level and the first switch element, first input state control module comprises the second fixed level, second switch unit and the second resistance unit, and the second input state control module is provided with the first resistance unit and the 3rd switch element.First fixed level is VDD, and the second fixed level is GND, and the first switch element is the 4th metal-oxide-semiconductor MP2, second switch unit is the 6th metal-oxide-semiconductor MN2,3rd switch element is the 5th metal-oxide-semiconductor MN1, and the second resistance unit is weak pull-down resistance R4, and the first resistance unit is strong pull-down resistance R3.

The source electrode of the 5th metal-oxide-semiconductor MN1 and the 6th metal-oxide-semiconductor MN2 is all connected with GND, the source electrode of the 4th metal-oxide-semiconductor MP2 is connected with VDD, 5th metal-oxide-semiconductor MN1, the 6th metal-oxide-semiconductor MN2 drain electrode be connected to strong pull-down resistance R3 and weak pull-down resistance R4, strong pull-down resistance R3 is connected with the drain electrode of the 4th metal-oxide-semiconductor MP2 with the other end of weak pull-down resistance R4, the drain electrode of the 4th metal-oxide-semiconductor MP2 is the input of I/O interface, and the 4th metal-oxide-semiconductor MP2, the 5th metal-oxide-semiconductor MN1 are connected with scanning monitor with the grid of the 6th metal-oxide-semiconductor MN2.Wherein, the 4th metal-oxide-semiconductor is PMOS, and the 5th metal-oxide-semiconductor MN1 and the 6th metal-oxide-semiconductor MN2 is NMOS tube, and the resistance of strong pull-down resistance R3 is the resistance of 15k and weak pull-down resistance R4 is 240k.

The grid level of the 4th metal-oxide-semiconductor MP2, the 5th metal-oxide-semiconductor MN1 and the 6th metal-oxide-semiconductor MN2 is labeled as S4, S5 and S6 in Figure 5 respectively, and on-off controller is by the level of a group of control signal configuration S4, S5 and S6.When S4, S5 and S6 are low level, drop-down I/O interface is in output high level state; When S4 and S5 is high level, when S6 is arbitrary value, drop-down I/O interface is in band strong pull-down input state; When S4 be high level, S5 be low level and S6 be high level time, drop-down I/O interface is in band weak pull-down input state.

Embodiment three:

With reference to Fig. 6, described pull-up I/O interface is connected with output state control module, the first input state control module and the second input state control module, output state control module is provided with the first fixed level and the first switch element, first input state control module comprises the second fixed level, second switch unit and the second resistance unit, and the second input state control module is provided with the first resistance unit and the 3rd switch element.First fixed level is GND, second fixed level is VDD, first switch element is the 7th metal-oxide-semiconductor MN3, second switch unit and the 3rd switch element are the 8th metal-oxide-semiconductor MP3 and the 9th metal-oxide-semiconductor MP4, second resistance unit is weak pull-up resistance R6 and strong pull-up resistance R5, and the first resistance unit is strong pull-up resistance R5.

The source electrode of the 8th metal-oxide-semiconductor MP3 is connected with VDD, the drain electrode of the 8th metal-oxide-semiconductor MP3 is connected with the source electrode of the 9th metal-oxide-semiconductor MP4, strong pull-up resistance R5 and weak pull-up resistance R6 is connected with in turn between the source electrode of the 8th metal-oxide-semiconductor MP3 and the drain electrode of the 7th metal-oxide-semiconductor MN3, the source electrode of the 9th metal-oxide-semiconductor MP4 and drain electrode are connected in parallel on weak pull-up resistance R6, the source electrode of the 7th metal-oxide-semiconductor MN3 is connected with GND, the input of the drain electrode I/O interface of the 7th metal-oxide-semiconductor MN3, the 7th metal-oxide-semiconductor MN3, the 8th metal-oxide-semiconductor MP3 are connected with on-off controller with the grid of the 9th metal-oxide-semiconductor MP4.7th metal-oxide-semiconductor MN3 is NMOS tube, and the 8th metal-oxide-semiconductor MP3 and the 9th metal-oxide-semiconductor MP4 is PMOS, and the resistance of strong pull-up resistance R5 is the resistance of 30k and weak pull-up resistance R6 is 50k.

The grid level of the 7th metal-oxide-semiconductor MN3, the 8th metal-oxide-semiconductor MP3 and the 9th metal-oxide-semiconductor MP4 is labeled as S7, S8 and S9 in figure 6 respectively, and on-off controller is by the level of a group of control signal configuration S7, S8 and S9.When S7 and S8 is high level, when S9 is arbitrary value, pull-up I/O interface is in output low level state; When S7, S8 and S9 are low level, pull-up I/O interface is in band strong pull-up input state; When S7 be low level, S8 be low level and S9 be high level time, pull-up I/O interface is in band weak pull-up input state.

Embodiment four:

With reference to Fig. 7, described drop-down I/O interface is connected with output state control module, the first input state control module and the second input state control module, output state control module is provided with the first fixed level and the first switch element, first input state control module comprises the second fixed level, second switch unit and the second resistance unit, and the second input state control module is provided with the first resistance unit and the 3rd switch element.First fixed level is VDD, second fixed level is GND, first switch element is the tenth metal-oxide-semiconductor MP5, second switch unit and the 3rd switch element are the 11 metal-oxide-semiconductor MN4 and the 12 metal-oxide-semiconductor MN5, second resistance unit is strong pull-down resistance R7 and weak pull-down resistance R8, and the first resistance unit is strong pull-down resistance R7.

The drain electrode of the tenth metal-oxide-semiconductor MP5 is connected with the drain electrode of the 12 metal-oxide-semiconductor MN5 by strong pull-down resistance R7, the source electrode of the 12 metal-oxide-semiconductor MN5 is connected with the drain electrode of the 11 metal-oxide-semiconductor MN4, the source electrode of the 11 metal-oxide-semiconductor MN4 is connected with GND, weak pull-down resistance R8 is parallel with between the source electrode of the 12 metal-oxide-semiconductor MN5 and drain electrode, the drain electrode of the tenth metal-oxide-semiconductor MP5 is the input of I/O interface, and the tenth metal-oxide-semiconductor MP5, the 11 metal-oxide-semiconductor MN4 are connected with scanning monitor with the grid of the 12 metal-oxide-semiconductor MN5.Wherein, the tenth metal-oxide-semiconductor MP5 is PMOS, and 11 metal-oxide-semiconductor MN4 and the 12 metal-oxide-semiconductor MN5 are NMOS tube, and the resistance of strong pull-down resistance R7 is the resistance of 45k and weak pull-down resistance R8 is 350k.

The grid level of the tenth metal-oxide-semiconductor MP5, the 11 metal-oxide-semiconductor MN4 and the 12 metal-oxide-semiconductor MN5 is labeled as S10, S11 and S12 in the figure 7 respectively, and on-off controller is by the level of a group of control signal configuration S10, S11 and S12.When S10 be low level, S11 be low level and S12 be arbitrary value time, drop-down I/O interface is in output high level state; When S10, S11 and S12 are high level, drop-down I/O interface is in band strong pull-down input state; When S10 be high level, S11 be high level and S12 be low level time, drop-down I/O interface is in band weak pull-down input state.

For the pull-up I/O interface in embodiment one and control signal, describe low-power consumption keyboard scanning method of the present invention in detail, be described for number N=6 of I/O interface, then I/O interface can be expressed as P1, P2, P3, P4, P5 and P6.

Utilize the pull-up I/O interface in embodiment one and control signal to complete low-power consumption dynamic keyboard scan method of the present invention, comprise the steps:

A) keyboard configuration is become to have the stepped keyboard of 6 I/O interfaces, be respectively P1-P6, stepped keyboard comprises 21 buttons, be respectively K01-K21, a button is connected between any two I/O interfaces, any one I/O interface is connected with GND by a button, and stepped keyboard is with reference to Fig. 8;

B) three kinds of I/O Interface status as described in embodiment one are set, are respectively output low level state, band strong pull-up input state and band weak pull-up input state;

C) preset scanning monitor scan period for the control information of 20ms and default control signal be S1, S2 and the S3 described in embodiment one;

What d1. configure I/O interface P1-P6 is in band weak pull-up input state, detect the input value of each I/O interface respectively, if detect, the level of all I/O interfaces is high level, then represent that the button between all I/O of being connected to interfaces and GND is scanned, and enter steps d 2; Any one I/O interface detects low level else if, then represent that the button be connected between this I/O interface and GND is pressed, output key detection signal;

D2. any one the I/O interface configured in all I/O interface P1-P6 is in output low level state, other all I/O interface is in band weak pull-up input state, detect all input values being in input state I/O interface respectively, if all high level detected, then represent that the button that all mouth I/O interfaces with being in output state are connected all is scanned, and enter steps d 3; Any one is in input state I/O interface and low level detected else if, then represent and be connected to this I/O interface and the button be between output state I/O interface is pressed, output key detection signal;

D3. will be in the I/O interface configuration of output state in steps d 2 for band strong pull-up input state, other all I/O interface is band weak pull-up input state, and this step does not carry out button detection; If all I/O interface P1-P6 are all scanned, enter steps d 4, otherwise get back to steps d 2 continuation scanning;

D4. configure the input state that all I/O interfaces are in band weak pull-up, stop key detection, and this beat is held time and can be pre-set; Then steps d 1 is returned according to the scan period of scanning monitor.

With reference to Figure 10, whole scanning step sequential chart of the present invention, as can be seen from the figure, complete scan period, each I/O interface, by the switching of steps d 2 to steps d 3, detects to realize button.With reference to Figure 11, when utilizing apparatus and method of the present invention to detect keyboard, I/O interface is obviously less than the time T0 of state of the prior art switching by time T1 during input state switching input state, and time T1 is specially the switching time that steps d 2 arrives steps d 3 in the present invention.

For the drop-down I/O interface in embodiment four and control signal, describe low-power consumption keyboard scanning method of the present invention in detail, be described for number N=6 of I/O interface, then I/O interface can be expressed as P1, P2, P3, P4, P5 and P6.

Utilize the drop-down I/O interface in embodiment four and control signal to complete low-power consumption dynamic keyboard scan method of the present invention, comprise the steps:

A) keyboard configuration is become to have the stepped keyboard of 6 I/O interfaces, be respectively P1-P6, stepped keyboard comprises 21 buttons, be respectively K01-K21, a button is connected between any two I/O interfaces, any one I/O interface is connected with VDD by a button, and stepped keyboard is with reference to Fig. 9;

B) three kinds of I/O Interface status as described in embodiment four are set, are respectively and export high level state, band strong pull-down input state and band weak pull-down input state;

C) preset scanning monitor scan period for the control information of 10ms and default control signal be S10, S11 and the S12 described in embodiment one;

What d1. configure I/O interface P1-P6 is in band weak pull-down input state, detect the input value of each I/O interface respectively, if detect, the level of all I/O interfaces is low level, then represent that the button between all I/O of being connected to interfaces and VDD is scanned, and enter steps d 2; Any one I/O interface detects high level else if, then represent that the button be connected between this I/O interface and VDD is pressed, output key detection signal;

D2. any one the I/O interface configured in all I/O interface P1-P6 is in output high level state, other all I/O interface is in band weak pull-down input state, detect all input values being in input state I/O interface respectively, if all low level detected, then represent that the button that all mouth I/O interfaces with being in output state are connected all is scanned, and enter steps d 3; Any one is in input state I/O interface and high level detected else if, then represent and be connected to this I/O interface and the button be between output state I/O interface is pressed, output key detection signal;

D3. will be in the I/O interface configuration of output state in steps d 2 for band strong pull-down input state, other all I/O interface is band weak pull-down input state, and this step does not carry out button detection; If all I/O interface P1-P6 are all scanned, enter steps d 4, otherwise get back to steps d 2 continuation scanning;

D4. configure the input state that all I/O interfaces are in band weak pull-down, stop key detection, and this beat is held time and can be pre-set; Then steps d 1 is returned according to the scan period of scanning monitor.

Embodiment five:

With reference to Figure 12, described drop-down I/O interface comprises the first fixed level, the second fixed level, the first switch element, second switch unit, the 3rd switch element, the second resistance unit, first resistance unit of the first fixed level of pull-up I/O interface, the second fixed level, the first switch element, second switch unit, the 3rd switch element, the second resistance unit, the first resistance unit and drop-down I/O interface, first fixed level of pull-up I/O interface, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively GND, VDD, 13 metal-oxide-semiconductor, 16 metal-oxide-semiconductor, 18 metal-oxide-semiconductor, weak pull-up resistance and strong pull-up resistance, first fixed level of drop-down I/O interface, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively VDD, GND, 14 metal-oxide-semiconductor, 15 metal-oxide-semiconductor, 17 metal-oxide-semiconductor, weak pull-up resistance and strong pull-up resistance.The source electrode of the 13 metal-oxide-semiconductor MN6, the 15 metal-oxide-semiconductor MN7 and the 17 metal-oxide-semiconductor MN8 is connected with GND, the source electrode of the 14 metal-oxide-semiconductor MP6, the 16 metal-oxide-semiconductor MP7 and the 18 metal-oxide-semiconductor MP8 is all connected with VDD, the drain electrode of the 18 metal-oxide-semiconductor MP8 is connected with the drain electrode of the 14 metal-oxide-semiconductor MP6 by strong pull-up resistance R9, and the drain electrode of the 16 metal-oxide-semiconductor MP7 is connected with the drain electrode of the 14 metal-oxide-semiconductor MP6 by weak pull-up resistance R10.The drain electrode of the 17 metal-oxide-semiconductor MN8 is connected with the drain electrode of the 13 metal-oxide-semiconductor MN6 by strong pull-down resistance R11, the drain electrode of the 15 metal-oxide-semiconductor MN7 is connected with the drain electrode of the 13 metal-oxide-semiconductor MN6 by weak pull-down resistance R12, the drain electrode of the 13 metal-oxide-semiconductor MN6 is connected with the drain electrode of the 14 metal-oxide-semiconductor MP6, the drain electrode of the 13 metal-oxide-semiconductor MN6 is the input of I/O interface, for connecting keyboard, 13 metal-oxide-semiconductor MN6, 14 metal-oxide-semiconductor MP6, 15 metal-oxide-semiconductor MN7, 16 metal-oxide-semiconductor MP7, 17 metal-oxide-semiconductor MN8 is all connected with on-off controller with the grid of the 18 metal-oxide-semiconductor MP8.Wherein, 13 metal-oxide-semiconductor MN6, the 15 metal-oxide-semiconductor MN7 and the 17 metal-oxide-semiconductor MN8 are NMOS tube, 14 metal-oxide-semiconductor MP6, the 16 metal-oxide-semiconductor MP7 and the 18 metal-oxide-semiconductor MP8 are PMOS, and the resistance of strong pull-up resistance R9, weak pull-up resistance R10, strong pull-down resistance R11 and weak pull-down resistance R12 is respectively 20k, 170k, 50k and 500k.

The grid level of the 13 metal-oxide-semiconductor MN6, the 14 metal-oxide-semiconductor MP6, the 15 metal-oxide-semiconductor MN7, the 16 metal-oxide-semiconductor MP7, the 17 metal-oxide-semiconductor MN8 and the 18 metal-oxide-semiconductor MP8 is labeled as S13, S14, S15, S16, S17 and S18 in fig. 12 respectively.On-off controller is by the level of a group of control signal configuration S13, S14, S15, S16, S17 and S18, and when S13, S14, S16 and S18 are high level, when S15 and S17 is low level, upper drop-down I/O interface is in output low level state; When S14 is high level, S13, S15, S17 and S18 are low level, and when S16 is arbitrary value, upper drop-down I/O interface is in band strong pull-up input state; When S14 and S18 is high level, when S13, S15, S16 and S17 are low level, upper drop-down I/O interface is in band weak pull-up input state; When S16 and S18 is high level, when S13, S14, S15 and S17 are low level, upper drop-down I/O interface is in output high level state; When S13 is low level, S14, S16, S17 and S18 are high level, and when S15 is arbitrary value, upper drop-down I/O interface is in band strong pull-down input state; When S13 and S17 is low level, when S14, S15, S16 and S18 are high level, upper drop-down I/O interface is in band weak pull-down input state.

Embodiment six:

With reference to Figure 13, described drop-down I/O interface has the output state control module of pull-up I/O interface, the output state control module of the first input state control module and the second input state control module and drop-down I/O interface, the first input state control module and the second input state control module.Be provided with the 19 metal-oxide-semiconductor MN9, the 20 metal-oxide-semiconductor MP9, the 21 metal-oxide-semiconductor MN10, the 22 metal-oxide-semiconductor MN11, the 23 metal-oxide-semiconductor MP10, the 24 metal-oxide-semiconductor MP11, strong pull-up resistance R13, weak pull-up resistance R14, strong pull-down resistance R15 and weak pull-down resistance R16.19 metal-oxide-semiconductor MN9 and the 21 metal-oxide-semiconductor MN10 source electrode on be connected with GND, the drain electrode of the 21 metal-oxide-semiconductor MN10 is serially connected with weak pull-down resistance R16 and strong pull-down resistance R15 successively, the other end of strong pull-down resistance R15 is connected with the drain electrode of the 19 metal-oxide-semiconductor MN9, and the source electrode of the 22 metal-oxide-semiconductor MN11 and drain electrode are connected in parallel on the two ends of weak pull-down resistance R16.20 metal-oxide-semiconductor MP9 and the 23 metal-oxide-semiconductor MP10 source electrode on be all connected with VDD, the drain electrode of the 23 metal-oxide-semiconductor MP10 is serially connected with weak pull-up resistance R14 and strong pull-up resistance R13 successively, the other end of strong pull-up resistance R13 is connected with the drain electrode of the 20 metal-oxide-semiconductor MP9, and the source electrode of the 24 metal-oxide-semiconductor MP11 and drain electrode are connected in parallel on the two ends of weak pull-up resistance R14.The drain electrode of the 20 metal-oxide-semiconductor MP9 is connected with the drain electrode of the 19 metal-oxide-semiconductor MN9, the drain electrode of the 20 metal-oxide-semiconductor MP9 is the input of I/O interface, for connecting keyboard, the 19 metal-oxide-semiconductor MN9, the 20 metal-oxide-semiconductor MP9, the 21 metal-oxide-semiconductor MN10, the 22 metal-oxide-semiconductor MN11, the 23 metal-oxide-semiconductor MP10 are all connected with scanning monitor with the grid of the 24 metal-oxide-semiconductor MP11.Wherein, 19 metal-oxide-semiconductor MN9, the 21 metal-oxide-semiconductor MN10 and the 22 metal-oxide-semiconductor MN11 are NMOS tube, 20 metal-oxide-semiconductor MP9, the 23 metal-oxide-semiconductor MP10 and the 24 metal-oxide-semiconductor MP11 are PMOS, and the resistance of strong pull-up resistance R13, weak pull-up resistance R14, strong pull-down resistance R15 and weak pull-down resistance R16 is respectively 35k, 420k, 40k and 280k.

The grid level of the 19 metal-oxide-semiconductor MN9, the 20 metal-oxide-semiconductor MP9, the 21 metal-oxide-semiconductor MN10, the 22 metal-oxide-semiconductor MN11, the 23 metal-oxide-semiconductor MP10 and the 24 metal-oxide-semiconductor MP11 is labeled as S19, S20, S21, S22, S23 and S24 in fig. 13 respectively.Scanning monitor is by the level of a group of control signal configuration S19, S20, S21, S22, S23 and S24, and when S21 is low level, S22 and S24 is arbitrary value, and when S19, S20 and S23 are high level, upper drop-down I/O interface is in output low level state; When S20 is high level, S22 is arbitrary value, and when S19, S21, S23 and S24 are low level, upper drop-down I/O interface is in band strong pull-up input state; When S20 and S24 is high level, S22 is arbitrary value, and when S19, S21 and S23 are low level, upper drop-down I/O interface is in band weak pull-up input state; When S23 is high level, S22 and S24 is arbitrary value, and when S19, S20 and S21 are low level, upper drop-down I/O interface is in output high level state; When S19 is low level, S24 is arbitrary value, and when S20, S21, S22 and S23 are high level, upper drop-down I/O interface is in band strong pull-down input state; When S19 and S22 is low level, S24 is arbitrary value, and when S20, S21 and S23 are high level, upper drop-down I/O interface is in band weak pull-down input state.

For the upper drop-down I/O interface in embodiment five and embodiment six and control signal, describe low-power consumption keyboard scanning method of the present invention in detail, be described for number N=6 of I/O interface, then I/O interface can be expressed as P1, P2, P3, P4, P5 and P6.

The present invention is low, and merit dynamically consumes keyboard scanning method, comprises the steps:

A) keyboard configuration is become to have the stepped keyboard of 6 I/O interfaces, be respectively P1-P6, stepped keyboard comprises 15 buttons, is respectively K01-K15, between any two I/O interfaces, connect a button, and stepped keyboard is with reference to Figure 14;

B) six kinds of I/O Interface status as described in embodiment five and embodiment six are set, are respectively output low level state, band strong pull-up input state, band weak pull-up input state, export high level state, band strong pull-down input state and band weak pull-down input state;

C) preset scanning monitor scan period for the control information of 20ms and default control signal be S13-S18 and S19-S24 described in embodiment five and embodiment six;

D1. any one the I/O interface configured in all I/O interface P1-P6 is in output low level state, other all I/O interface is in band weak pull-up input state, detect all input values being in input state I/O interface respectively, if all high level detected, then represent that the button that all mouth I/O interfaces with being in output state are connected all is scanned, and enter steps d 2; Any one is in input state I/O interface and low level detected else if, then represent and be connected to this I/O interface and the button be between output state I/O interface is pressed, output key detection signal;

D2. will be in the I/O interface configuration of output state in steps d 1 for band strong pull-up input state, other all I/O interface is band weak pull-up input state, and this step does not carry out button detection; If all I/O interface P1-P6 are all scanned, enter steps d 3, otherwise get back to steps d 1 continuation scanning;

D3. configure the input state that all I/O interfaces are in band weak pull-up, stop key detection, and this beat is held time and can be pre-set; Then steps d 4 is entered according to the scan period of scanning monitor;

D4. any one the I/O interface configured in all I/O interface P1-P6 is in output high level state, other all I/O interface is in band weak pull-down input state, detect all input values being in input state I/O interface respectively, if all low level detected, then represent that the button that all mouth I/O interfaces with being in output state are connected all is scanned, and enter steps d 5; Any one is in input state I/O interface and high level detected else if, then represent and be connected to this I/O interface and the button be between output state I/O interface is pressed, output key detection signal;

D5. will be in the I/O interface configuration of output state in steps d 4 for band strong pull-down input state, other all I/O interface is band weak pull-down input state, and this step does not carry out button detection; If all I/O interface P1-P6 are all scanned, enter steps d 6, otherwise get back to steps d 4 continuation scanning;

D6. configure the input state that all I/O interfaces are in band weak pull-down, stop key detection, and this beat is held time and can be pre-set; Then steps d 1 is returned according to the scan period of scanning monitor.

Illustrate that scanning means is at the electric current of all internal consumptions of whole scanning under Standard resistance range is the strong pull-up resistance of 5K-50K or strong pull-down resistance below by emulated data.For the pull-up I/O interface in embodiment one and its scan method, emulate the average current of single I/O interface within a scan period and be described, wherein oscillator current is not taken into account.

To arrange simulated conditions be VDD is 3V, and temperature is 25 degrees Celsius, and weak pull-up resistance or weak pull-down resistance are 150K, and weak pull-up resistance or weak pull-down resistance can select the different resistances in 50K-500K.D1-d4 step is comprised in the scanning step of pull-up I/O interface, wherein, d1 is two clock cycle, and d2 is a clock cycle, and d3 is a clock cycle, circulation in d2-d3 step is 16 times altogether, d4 is set to 0, and therefore, complete scan period is 34 clock cycle, each clock cycle is 50us, and clock is provided by oscillator.Because the size of parasitic capacitance not easily judges, different capacitor equivalent parasitic capacitances is selected to judge when emulating.

Data as shown in table 1 below are obtained by emulation, when in table, the parasitic capacitance of file is different value, the corresponding current value consumed, when the different strong pull-up resistance walked crosswise are different value, the corresponding current value consumed, in table 1, last is classified as in prior art the current value consumed under different parasitic capacitance that only there is weak pull-up resistance, and in table, the unit of current value is nA.

The current value that table 1 single I/O interface is corresponding under different parasitic capacitance and different strong pull-up resistance

As can be seen from Table 1, under the strong pull-up resistance of similar resistance, parasitic capacitance is larger, and in the whole scan period, the electric current of mean consumption is larger; Under identical parasitic capacitance, the resistance of strong pull-up resistance is less, and in the whole scan period, the electric current of mean consumption is less; When not using strong pull-up resistance, the current value that single I/O interface consumes under different parasitic capacitance is obviously greater than the current value after adding strong pull-up resistance.Because the consumption of electric current is mainly in d2-d3 step time standby, and d2-d3 needs circulation 16 times complete scan period, therefore obtains emulated data as shown in table 2 below.

Table 2 current value that all I/O interface is corresponding under different parasitic capacitance and different strong pull-up resistance

Considering that general chip pin adds that pcb board is easy to reach more than 20pf for the parasitic capacitance of each I/O interface, is that 20pf is briefly described at this host age preference electric capacity.Suppose that the electric current providing the oscillator of scan period itself to consume is 0.5uA, in the prior art, when only adopting weak pull-up resistance to be the 150K in table, when scanning, standby electric current is 0.5uA+1.575uA, is 2.075uA altogether; And under technology of the present invention, when scanning, standby electric current is 0.5uA+0.704uA, is 1.204uA altogether, when this means to use device of the present invention to scan, make the stand-by time of product extend the time of (2.075uA-1.204uA)/2.075uA*100%, be 42%.

For the embodiment one to six that the present invention is representative, all can refer to above-mentioned emulation mode and obtain corresponding emulated data, do not repeat them here.In above-mentioned explanation, all special instructions that do not add, all adopt routine techniques means of the prior art.

Claims

1. an I/O interface circuit, comprise the output state control module and the first input state control module that are connected with I/O interface, output state control module comprises the first fixed level and the first switch element that are connected in turn, the other end of the first switch element is connected with I/O interface, first input state control module comprises the second fixed level be connected in turn, second switch unit and the second resistance unit, the other end of the second resistance unit is connected with I/O interface, the control end of the first switch element and second switch unit is connected with the on-off controller for control switch cell conduction or disconnection, first fixed level is contrary with the second fixed level logic, it is characterized in that, described I/O interface circuit is also connected with the second input state control module, second input state control module is provided with the first resistance unit for shortening I/O interface level switching time and the 3rd switch element, second fixed level, 3rd switch element is connected in turn with the first resistance unit, the other end of the first resistance unit is connected with I/O interface, the control end of the 3rd switch element is connected with on-off controller, on-off controller exports the conducting state that control information controls the first switch element, second switch unit and the 3rd switch element, and to configure the I/O interface be connected with the first switch element place module of conducting be respectively output first fixed level state, the I/O interface be connected with the second switch unit place module of conducting is the first input state, and the I/O interface be connected with the 3rd switch element place module of conducting is the second input state, described on-off controller at least comprises one group of control information, makes the I/O interface configuration being in output first fixed level state be the second input state,

When described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, then the first fixed level is low level, second fixed level is high level, described first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is output low level state, first input state is band weak pull-up input state, and the second input state is band strong pull-up input state;

When described I/O interface circuit is the drop-down I/O interface circuit of built-in pull-down structure, then the first fixed level is high level, second fixed level is low level, described first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, described output first fixed level state is for exporting high level state, first input state is band weak pull-down input state, and the second input state is band strong pull-down input state;

When described I/O interface circuit is the upper drop-down I/O interface circuit of built-in upper pull-up structure and pull-down structure simultaneously, upper drop-down I/O interface circuit comprises two groups of I/O interface circuits, is respectively pull-up I/O interface circuit and drop-down I/O interface circuit; First fixed level of described pull-up I/O interface circuit is low level, second fixed level is high level, first resistance unit is strong pull-up resistance, second resistance unit is weak pull-up resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is output low level state, and the first input state is band weak pull-up input state, and the second input state is band strong pull-up input state; First fixed level of described drop-down I/O interface circuit is high level, second fixed level is low level, first resistance unit is strong pull-down resistance, second resistance unit is weak pull-down resistance, first switch element, second switch unit and the 3rd switch element are respectively the metal-oxide-semiconductor for controlling above-mentioned resistance access state, the first fixed level state that exports is for exporting high level state, and the first input state is band weak pull-down input state, and the second input state is band strong pull-down input state.

2. I/O interface circuit according to claim 1, it is characterized in that, when described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, described first fixed level is GND, second fixed level is VDD, first switch element is the first metal-oxide-semiconductor, and second switch unit is the 3rd metal-oxide-semiconductor, and the 3rd switch element is the second metal-oxide-semiconductor; Second metal-oxide-semiconductor is all connected with VDD with the source electrode of the 3rd metal-oxide-semiconductor, the source electrode of the first metal-oxide-semiconductor is connected with GND, second metal-oxide-semiconductor is connected with weak pull-up resistance with strong pull-up resistance respectively with the drain electrode of the 3rd metal-oxide-semiconductor, strong pull-up resistance is connected with the drain electrode of the first metal-oxide-semiconductor with the other end of weak pull-up resistance, the drain electrode of the first metal-oxide-semiconductor is the input of I/O interface, and the first metal-oxide-semiconductor, the second metal-oxide-semiconductor are all connected with on-off controller with the grid of the 3rd metal-oxide-semiconductor.

3. I/O interface circuit according to claim 1, it is characterized in that, when described I/O interface circuit is the drop-down I/O interface circuit of built-in pull-down structure, described first fixed level is VDD, second fixed level is GND, first switch element is the 4th metal-oxide-semiconductor, and second switch unit is the 6th metal-oxide-semiconductor, and the 3rd switch element is the 5th metal-oxide-semiconductor; 5th metal-oxide-semiconductor is all connected with GND with the source electrode of the 6th metal-oxide-semiconductor, the source electrode of the 4th metal-oxide-semiconductor is connected with VDD, 5th metal-oxide-semiconductor is connected with weak pull-down resistance with strong pull-down resistance respectively with the drain electrode of the 6th metal-oxide-semiconductor, strong pull-down resistance is connected with the drain electrode of the 4th metal-oxide-semiconductor with the other end of weak pull-down resistance, the drain electrode of the 4th metal-oxide-semiconductor is the input of I/O interface, and the 4th metal-oxide-semiconductor, the 5th metal-oxide-semiconductor are connected with on-off controller with the grid of the 6th metal-oxide-semiconductor.

4. I/O interface circuit according to claim 1, it is characterized in that, when described I/O interface circuit is the upper drop-down I/O interface circuit of built-in upper pull-up structure and pull-down structure simultaneously, first fixed level of described pull-up I/O interface circuit, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively GND, VDD, 13 metal-oxide-semiconductor, 16 metal-oxide-semiconductor, 18 metal-oxide-semiconductor, weak pull-up resistance and strong pull-up resistance, first fixed level of drop-down I/O interface, second fixed level, first switch element, second switch unit, 3rd switch element, second resistance unit and the first resistance unit are respectively VDD, GND, 14 metal-oxide-semiconductor, 15 metal-oxide-semiconductor, 17 metal-oxide-semiconductor, weak pull-down resistance and strong pull-down resistance, 13 metal-oxide-semiconductor, 15 metal-oxide-semiconductor is all connected with GND with the source electrode of the 17 metal-oxide-semiconductor, 14 metal-oxide-semiconductor, 16 metal-oxide-semiconductor is all connected with VDD with the source electrode of the 18 metal-oxide-semiconductor, the drain electrode of the 18 metal-oxide-semiconductor is connected by the drain electrode of strong pull-up resistance with the 14 metal-oxide-semiconductor, the drain electrode of the 16 metal-oxide-semiconductor is connected by the drain electrode of weak pull-up resistance with the 14 metal-oxide-semiconductor, the drain electrode of the 17 metal-oxide-semiconductor is connected by the drain electrode of strong pull-down resistance with the 13 metal-oxide-semiconductor, the drain electrode of the 15 metal-oxide-semiconductor is connected by the drain electrode of weak pull-down resistance with the 13 metal-oxide-semiconductor, the drain electrode of the 13 metal-oxide-semiconductor is connected with the drain electrode of the 14 metal-oxide-semiconductor, the drain electrode of the 13 metal-oxide-semiconductor is the input of I/O interface, 13 metal-oxide-semiconductor, 14 metal-oxide-semiconductor, 15 metal-oxide-semiconductor, 16 metal-oxide-semiconductor, 17 metal-oxide-semiconductor is all connected with on-off controller with the grid of the 18 metal-oxide-semiconductor.

5. I/O interface circuit according to claim 1 and 2, is characterized in that, the Standard resistance range of described strong pull-up resistance is 5K-50K, and the Standard resistance range of weak pull-up resistance is 50K-500K.

6. the I/O interface circuit according to claim 1 or 3, is characterized in that, the Standard resistance range of described strong pull-down resistance is 5K-50K, and the Standard resistance range of weak pull-down resistance is 50K-500K.

7. the I/O interface circuit according to claim 1 or 4, is characterized in that, the Standard resistance range of described strong pull-up resistance and strong pull-down resistance is 5K-50K, and the Standard resistance range of weak pull-up resistance and weak pull-down resistance is 50K-500K.

8. a low-power consumption key scan device, described scanning means is at least connected with a button, it is characterized in that, the two ends of described button are connected to I/O interface circuit as claimed in claim 1.

9. a low-power consumption key scanning method, is characterized in that, the realization of described scan method, based on scanning means as claimed in claim 8, comprises the steps:

10. a low-power consumption dynamic keyboard scan method, is characterized in that, the realization of described scan method is based on pull-up I/O interface circuit as claimed in claim 1, and described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, comprises the steps:

11. 1 kinds of low-power consumption dynamic keyboard scan methods, is characterized in that, the realization of described scan method is based on drop-down I/O interface circuit as claimed in claim 1, and described I/O interface circuit is the pull-up I/O interface circuit of built-in upper pull-up structure, comprises the steps: