CN103391085B - Share a pin to detect circuit and method and the input key system of multiple buttons - Google Patents
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- CN103391085B CN103391085B CN201210143323.7A CN201210143323A CN103391085B CN 103391085 B CN103391085 B CN 103391085B CN 201210143323 A CN201210143323 A CN 201210143323A CN 103391085 B CN103391085 B CN 103391085B
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Abstract
The present invention provides a shared pin to detect circuit and method and the input key system of multiple buttons.In one embodiment, there is provided and determine electric current by this pin to key-press module, thus produce the voltage relevant to the equivalent resistance of this key-press module at this pin, and compare the voltage of this pin and one group of reference value learns the pressing situation of the multiple buttons in this key-press module；In another embodiment, apply variable current to this pin, adjust this variable current and make the stable voltage of this pin maintenance, and compare this variable current and one group of reference value learns the pressing situation of the multiple buttons in this key-press module.
Description
Technical field
The present invention is relevant a kind of key detection circuit, especially with regard to a kind of pin that shares to detect circuit and the method for multiple buttons.
Background technology
As shown in Figure 1, existing key detection chip 10 is in order to detect multiple button B1, B2 and B3, need different pin P1, P2 and P3 connects button B1 respectively, the key circuit 12 at B2 and B3 place, 14 and 16, and a key circuit only has one key (such as key circuit 16) in series with a resistor or (such as key circuit 12 and 14) in parallel, as button B1, B2, when B3 is pressed, from each pin P1, the key circuit 12 that P2 and P3 observes, 14, the equivalent resistance of 16 can change, pin P1, there is respective circuit for detecting 18 rear end of P2 and P3, 20 and 22 judge button B1 accordingly, whether B2 and B3 is pressed.Owing to each button needs a pin and a circuit for detecting, cost and the size of chip therefore can be increased in the application that number of keys is more.
Summary of the invention
An object of the present invention, is to propose a kind of pin that shares to detect circuit and the method for multiple buttons.
An object of the present invention, is to propose a kind of pin that shares to detect the input key system of multiple buttons.
According to the present invention, a kind of pin that shares is to detect circuit and method and the input key system of multiple buttons, it is to determine electric current by this pin to key-press module by offer, to produce the voltage relevant to the equivalent resistance of this key-press module at this pin, and compare the voltage of this pin and one group of reference value learns the pressing situation of the multiple buttons in this key-press module.
According to the present invention, a kind of pin that shares is to detect circuit and method and the input key system of multiple buttons, it is by applying variable current to this pin, adjusting this variable current makes this pin maintain stable voltage, and compares this variable current and one group of reference value learns the pressing situation of the multiple buttons in this key-press module.
The present invention has only to single pin can detect multiple button, and multiple buttons in key-press module and resistance can have the configuration mode of any kenel, as long as its pressing situation can change the equivalent resistance of this key-press module.In the application that number of keys is more, the present invention can save the pin of a lot of key detection chip, packaging cost is greatly reduced, and has only to single circuit for detecting, the area of chip is greatly decreased.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of existing key detection chip；
Fig. 2 is according to the first embodiment of the present invention；And
Fig. 3 is according to the second embodiment of the present invention.
Drawing reference numeral:
10 key detection chips
12 key circuits
14 key circuits
16 key circuits
18 circuit for detecting
20 circuit for detecting
22 circuit for detecting
24 key detection chips
26 circuit for detecting
28 key-press modules
30 constant current sources
32 voltage comparators
34 charge-discharge circuits
36 key detection chips
38 circuit for detecting
40 key-press modules
42 mu balanced circuits
44 current sources
46 current comparators
48 operational amplifiers
Detailed description of the invention
Fig. 2 is according to the first embodiment of the present invention, an input key system is formed with outside key-press module 28 at the circuit for detecting 26 within key detection chip 24, the two connects each other through pin Ps, and circuit for detecting 26 can detect the multiple buttons in key-press module 28 by this single pin Ps.
In order to explain orally the running of circuit for detecting 26, it is assumed that key-press module 28 includes that resistance R4, R5 and R0 are connected between pin Ps and earth terminal GND, and button B4 is in parallel with resistance R4, and button B5 is in parallel with resistance R5, resistance valueThe equivalent resistance of the key-press module 28 observed from pin Ps can change because of the pressing situation of button B4 and B5, when button B4 and B5 is not all pressed, the equivalent resistance of key-press module 28 is equal to 4R0, when only button B4 is pressed, the equivalent resistance of key-press module 28 is equal to 3R0, and when only button B5 is pressed, the equivalent resistance of key-press module 28 is equal to 2R0, when button B4 and B5 is all pressed, the equivalent resistance of key-press module 28 is equal to R0.
In the present embodiment, circuit for detecting 26 includes current source 30 connecting leads Ps, there is provided and determine electric current Ic by pin Ps to key-press module 28, owing to electric current Ic is definite value, and the equivalent resistance of key-press module 28 is the pressing situation according to button B4 and B5 and changes, so be appreciated that the pressing situation of button B4 and B5 from the voltage V1 of pin Ps.Circuit for detecting 26 further includes voltage comparator 32 connecting leads Ps, and the voltage V1 and one group of reference value Vref that compare pin Ps produce output signal Sout to reflect the pressing situation of button B4 and B5.
Preferably, circuit for detecting 26 further includes charge-discharge circuit 34 connecting leads Ps, to pin Ps precharge or pre-arcing, reaches stable accelerating the voltage V1 of pin Ps, promotes the response speed of circuit for detecting 26.In this embodiment, charge-discharge circuit 34 includes that bridge transistor M1 is connected between voltage source VDD and pin Ps, and lower bridge transistor M2 is connected between pin Ps and earth terminal GND, transistor M1 and M2 serves as switch, the control of suspension control signal Sm1 and Sm2 respectively, when transistor M1 turns on, pin Ps is charged by voltage source VDD through transistor M1, when transistor M2 turns on, pin Ps discharges into earth terminal GND through transistor M2.In other embodiments, charge-discharge circuit 34 only includes bridge transistor M1 or lower bridge transistor M2.
In the various application of key detection chip 24, it is floating that outside key-press module is likely to result in pin Ps, it is floating that the key circuit 16 of such as Fig. 1 will result in pin Ps when button B3 is not pressed, the voltage V1 causing pin Ps floats, in order to avoid this situation occurs, circuit for detecting 26 further includes initialization resistance Rini or switch SW1 and is connected between pin Ps and earth terminal GND, to initialize the voltage V1 of pin Ps, it is to avoid it floats.Preferably, circuit for detecting 26 includes that initializing resistance Rini and switch SW1 is connected between pin Ps and earth terminal GND, when switching SW1 Guan Bi, the voltage V1 of pin Ps can be initialized, when applications keys detecting chip 24, according to key-press module 28, user can judge whether pin Ps has the situation that voltage floats, decide whether the voltage V1 utilizing enable signal Sen to initialize pin Ps.In other embodiments, also can change into being connected between pin Ps and certain voltage source (such as VDD) initialization resistance Rini or switch SW1 or its tandem compound.
Fig. 3 is according to the second embodiment of the present invention, an input key system is formed with outside key-press module 40 at the circuit for detecting 38 within key detection chip 36, the two connects each other through pin Ps, and circuit for detecting 38 can detect the multiple buttons in key-press module 40 by this single pin Ps.
In order to explain orally the running of circuit for detecting 38, assume that key-press module 40 includes that button B6 and resistance R6 is connected between pin Ps and earth terminal GND, and button B7 and resistance R7, R0 are connected between pin Ps and earth terminal GND, and resistance R0 is connected between pin Ps and button B7, R6=R7=R0, when only button B6 is pressed, the equivalent resistance of key-press module 40 is equal to R0, when only button B7 is pressed, the equivalent resistance of key-press module 40 is equal to 2R0, when button B6 and B7 is all pressed, the equivalent resistance of key-press module 40 is equal toWhen button B4 and B7 is not all pressed, pin Ps is floating.As the embodiment of Fig. 2 had been described above, connect between pin Ps and earth terminal GND or voltage source and initialize resistance Rini or switch SW1 or its tandem compound, can avoid the voltage V1 of pin Ps to float.In other embodiments, also can change initialize resistance Rini as be arranged in the outside of key detection chip 36 into, such as in key-press module 40 or the non-essential resistance of connecting leads Ps.
In the present embodiment, circuit for detecting 38 includes mu balanced circuit 42 connecting leads Ps, current source 44 provides the first variable electric current I1 to be applied to pin Ps by mu balanced circuit 42, pin Ps is maintained the first voltage V1 by mu balanced circuit 42, therefore the change of the equivalent resistance of key-press module 40 can cause the first electric current I1 to change, in order to detect the change of the first electric current I1, current source 44 includes that current mirror mirror the first electric current I1 produces the second electric current I2, compare with one group of reference value through current comparator 46 and produce output signal Sout, to reflect the pressing situation of button B6 and B7.
In the present embodiment, current comparator 46 includes that reference resistance Rref is connected between current source 44 and earth terminal GND, second electric current I2 is converted to the second voltage V2, and voltage comparator 32 compares the second voltage V2 and one group of reference value Vref produces output signal Sout.
In the present embodiment, mu balanced circuit 42 includes that transistor M3 and resistance R8 is connected between current source 44 and pin Ps, and operational amplifier 48 controls transistor M3, one input of operational amplifier 48 accepts reference voltage Vc, another input connecting leads Ps, outfan provides error signal Sd to be applied to the grid of transistor M3, the voltage V1 of pin Ps can be maintained Vc by this electrical combination, when the equivalent resistance of key-press module 40 changes, in order to maintain the voltage of pin Ps at Vc, operational amplifier 48 meeting alignment error signal Sd is to change the electric current I1 of transistor M3, the reacting condition of this electric current I1 is to electric current I2, and then it is reacted to output signal Sout.Preferably, mu balanced circuit 42 further includes between input and the pin Ps that resistance R9 is connected to operational amplifier 48.
As the embodiment of Fig. 2 had been described above, circuit for detecting 38 can also use charge-discharge circuit 34 to pin Ps precharge or pre-arcing, reaches stable accelerating the voltage V1 of pin Ps, promotes the response speed of circuit for detecting 38.
As above embodiment is shown, the present invention has only to single pin can detect multiple button, and multiple buttons in key-press module and resistance can have the configuration mode of any kenel, as long as its pressing situation can change the equivalent resistance of this key-press module.In the application that number of keys is more, the present invention can save the pin of a lot of key detection chip, packaging cost is greatly reduced, and has only to single circuit for detecting, the area of chip is greatly decreased.
The purpose being stated as illustrating above presently preferred embodiments of the present invention made, and it is not intended to limit the form that the present invention is accurately disclosed, learn and make an amendment or change to be possible based on above teaching or from embodiments of the invention, embodiment is to explain orally the principle of the present invention and allow those skilled in the art utilize the present invention select in reality application and describe with various embodiments, and the technological thought attempt of the present invention is determined by claim and equalization thereof.
Claims (25)
1. one kind shares a pin to detect the circuit of multiple buttons, it is characterized in that, the plurality of button is connected described pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, and the described pin that shares includes with the circuit detecting multiple buttons:
Constant current source, connects described pin, it is provided that determines electric current by described pin to described key-press module, produces the voltage relevant to the equivalent resistance of described key-press module at described pin；
Voltage comparator, connects described pin, and relatively voltage and one group of reference value of described pin produces output signal, to react the pressing situation of the plurality of button；And
Initialize resistance or switch or its tandem compound is connected between described pin and earth terminal or voltage source, to initialize the voltage of described pin.
2. circuit as claimed in claim 1, it is characterised in that the described pin that shares further includes the charge-discharge circuit described pin of connection with the circuit detecting multiple buttons, to the precharge of described pin or pre-arcing, to accelerate the speed of key detection.
3. circuit as claimed in claim 2, it is characterised in that described charge-discharge circuit includes that the first transistor is connected between voltage source and described pin, and transistor seconds is connected between described pin and earth terminal.
4. one kind shares a pin with the method detecting multiple buttons, it is characterised in that the plurality of button is connected described pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, said method comprising the steps of:
Initialize the voltage of described pin；
There is provided and determine electric current by described pin to described key-press module, produce the voltage relevant to the equivalent resistance of described key-press module at described pin；And
Relatively voltage and one group of reference value of described pin produces output signal, to react the pressing situation of the plurality of button.
5. method as claimed in claim 4, it is characterised in that the described pin that shares further includes the precharge of described pin or pre-arcing with the method detecting multiple buttons, to accelerate the speed of key detection.
6. an input key system, it is characterised in that described input key system includes:
Multiple buttons are connected a pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, and described key-press module has an equivalent resistance, and described equivalent resistance changes according to the pressing situation of the plurality of button；
Constant current source, connects described pin, it is provided that determines electric current by described pin to described key-press module, produces the voltage relevant to described equivalent resistance at described pin；
Voltage comparator, connects described pin, and relatively voltage and one group of reference value of described pin produces output signal, to react the pressing situation of the plurality of button；And
Initialize resistance or switch or its tandem compound is connected between described pin and earth terminal or voltage source, to initialize the voltage of described pin.
7. input key system as claimed in claim 6, it is characterised in that described input key system further includes charge-discharge circuit and connects described pin, to the precharge of described pin or pre-arcing, to accelerate the speed of key detection.
8. input key system as claimed in claim 7, it is characterised in that described charge-discharge circuit includes that the first transistor is connected between voltage source and described pin, and transistor seconds is connected between described pin and earth terminal.
9. one kind shares a pin to detect the circuit of multiple buttons, it is characterized in that, the plurality of button is connected described pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, and the described pin that shares includes with the circuit detecting multiple buttons:
Current source, it is provided that the first variable electric current and second electric current relevant to described first electric current；
Mu balanced circuit, connects described pin and described current source, and described first electric current is applied to described pin, and adjusts described first electric current and make described pin maintain the first voltage；And
Current comparator, connects described current source, and relatively described second electric current and one group of reference value produces output signal, to react the pressing situation of the plurality of button.
10. circuit as claimed in claim 9, it is characterised in that described current source includes that described in current mirror mirror, the first electric current produces described second electric current.
11. circuit as claimed in claim 9, it is characterised in that described mu balanced circuit includes:
Transistor and resistant series are between described current source and described pin；And
Operational amplifier, has first input end and accepts reference voltage, and the second input connects described pin, and outfan provides error signal to be applied to the grid of described transistor, to control described first electric current.
12. circuit as claimed in claim 9, it is characterised in that described current comparator includes:
Resistance, is connected between described current source and earth terminal, and described second electric current is converted to the second voltage；And
Voltage comparator, relatively described second voltage and described group of reference value produce described output signal.
13. circuit as claimed in claim 9, it is characterised in that it is characterized in that, the described pin that shares further includes the charge-discharge circuit described pin of connection with the circuit detecting multiple buttons, to the precharge of described pin or pre-arcing, to accelerate the speed of key detection.
14. circuit as claimed in claim 9, it is characterized in that, it is characterized in that, a described shared pin further includes initialization resistance or switch with the circuit detecting multiple buttons or its tandem compound is connected between described pin and earth terminal or voltage source, to initialize the voltage of described pin.
15. 1 kinds share a pin with the method detecting multiple buttons, it is characterised in that the plurality of button is connected described pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, said method comprising the steps of:
A, provide the first variable electric current and second electric current relevant to described first electric current；
B, described first electric current is applied to described pin, and adjusts described first electric current and make described pin maintain the first voltage；And
Second electric current described in C, comparison and one group of reference value produce output signal, to react the pressing situation of the plurality of button.
The method of 16. such as claim 15, it is characterised in that described step A includes that described in mirror, the first electric current produces described second electric current.
The method of 17. such as claim 15, it is characterised in that described step C comprises the following steps:
Described second electric current is converted to the second voltage；And
Relatively described second voltage and described group of reference value produces described output signal.
The method of 18. such as claim 15, it is characterised in that described method further includes the precharge of described pin or pre-arcing, to accelerate the speed of key detection.
The method of 19. such as claim 15, it is characterised in that described method further includes the voltage initializing described pin.
20. 1 kinds of input key systems, it is characterised in that described input key system includes:
Multiple buttons are connected a pin with the resistant series of the resistor coupled in parallel of multiple series connection or multiple parallel connection with composition key-press module respectively, and described key-press module has an equivalent resistance, and described equivalent resistance changes according to the pressing situation of the plurality of button；
Current source, it is provided that the first variable electric current and second electric current relevant to described first electric current；
Mu balanced circuit, connects described pin and described current source, and described first electric current is applied to described pin, and adjusts described first electric current and make described pin maintain the first voltage；And
Current comparator, connects described current source, and relatively described second electric current and one group of reference value produces output signal, to react the pressing situation of the plurality of button.
The input key system of 21. such as claim 20, it is characterised in that described current source includes that described in current mirror mirror, the first electric current produces described second electric current.
The input key system of 22. such as claim 20, it is characterised in that described mu balanced circuit includes:
Transistor and resistant series are between described current source and described pin；And
Operational amplifier, has first input end and accepts reference voltage, and the second input connects described pin, and outfan provides error signal to be applied to the grid of described transistor, to control described first electric current.
The input key system of 23. such as claim 20, it is characterised in that described current comparator includes:
Resistance, is connected between described current source and earth terminal, and described second electric current is converted to the second voltage；And
Voltage comparator, relatively described second voltage and described group of reference value produce described output signal.
The input key system of 24. such as claim 20, it is characterised in that described input key system further includes charge-discharge circuit and connects described pin, to the precharge of described pin or pre-arcing, to accelerate the speed of key detection.
The input key system of 25. such as claim 20, it is characterised in that described input key system further includes initialization resistance or switch or its tandem compound is connected between described pin and earth terminal or voltage source, to initialize the voltage of described pin.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210143323.7A CN103391085B (en) | 2012-05-10 | 2012-05-10 | Share a pin to detect circuit and method and the input key system of multiple buttons |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210143323.7A CN103391085B (en) | 2012-05-10 | 2012-05-10 | Share a pin to detect circuit and method and the input key system of multiple buttons |
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| CN103391085B true CN103391085B (en) | 2016-08-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106549671A (en) * | 2016-10-09 | 2017-03-29 | 北京远特科技股份有限公司 | A kind of keypress function expanded circuit |
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| CN1246221A (en) * | 1996-12-19 | 2000-03-01 | 艾利森电话股份有限公司 | Apparatus and method for keyboard encoding |
| CN1302478A (en) * | 1998-05-22 | 2001-07-04 | 夸尔柯姆股份有限公司 | Differentiating between input range in passive keyboard |
| CN1952853A (en) * | 2005-10-18 | 2007-04-25 | 普诚科技股份有限公司 | Key apparatus and detecting method thereof |
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| JP4427365B2 (en) * | 2004-03-19 | 2010-03-03 | 株式会社東芝 | Semiconductor memory device |
| JP4308812B2 (en) * | 2005-10-28 | 2009-08-05 | 日本テキサス・インスツルメンツ株式会社 | Light emitting element driving device |
| JP4779793B2 (en) * | 2006-05-01 | 2011-09-28 | 株式会社デンソー | AD converter and electronic control device |
| US7688230B2 (en) * | 2006-07-13 | 2010-03-30 | Emerson Electric Co. | Switching device with critical switch detection |
| US8193834B2 (en) * | 2010-02-12 | 2012-06-05 | Fairchild Semiconductor Corporation | Multiple detection circuit for accessory jacks |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0641086A1 (en) * | 1993-08-26 | 1995-03-01 | GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH & Co. KG | Device for the interrogation of control elements |
| CN1246221A (en) * | 1996-12-19 | 2000-03-01 | 艾利森电话股份有限公司 | Apparatus and method for keyboard encoding |
| CN1302478A (en) * | 1998-05-22 | 2001-07-04 | 夸尔柯姆股份有限公司 | Differentiating between input range in passive keyboard |
| CN1952853A (en) * | 2005-10-18 | 2007-04-25 | 普诚科技股份有限公司 | Key apparatus and detecting method thereof |
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