CN110401452A - Button multiplexing circuit and its button multiplexing method - Google Patents
Button multiplexing circuit and its button multiplexing method Download PDFInfo
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- CN110401452A CN110401452A CN201810377211.5A CN201810377211A CN110401452A CN 110401452 A CN110401452 A CN 110401452A CN 201810377211 A CN201810377211 A CN 201810377211A CN 110401452 A CN110401452 A CN 110401452A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M11/00—Coding in connection with keyboards or like devices, i.e. coding of the position of operated keys
- H03M11/20—Dynamic coding, i.e. by key scanning
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Abstract
The invention discloses a kind of button multiplexing circuits, comprising: the micro-control unit with key scan output end, multiplexing end；First push-button array；Key scan output circuit；Key scan input circuit；And load circuit, the first input branch and the second input branch have been arranged in parallel on key scan input circuit, micro-control unit limits to make the first input branch detect the first indication signal for being used to indicate the first push-button array and acting under the premise of load is not connected by driving the real-time current potential of the second connecting side for controlling key scan input circuit in key scan working condition, when load drives working condition, control key scan input circuit is not limited the real-time current potential of the second connecting side so that the second input branch detects the second indication signal for being used to indicate the movement of the first push-button array.Achieve the purpose that the circuit is attempted to carry out button multiplexing on load driving circuits based on existing key scan and load driving circuits.
Description
Technical field
The present invention relates to the chip for having keypress function or system, in particular to a kind of button multiplexing circuit and its key are multiple
Use method.
Background technique
The existing chip for having keypress function or system, with micro-control unit (Micro Controll Unit, MCU)
Key scan is realized in the input and output port (Input/Output, I/O) or dedicated key scan port.The port I/O is also known as
Make the port I/O, such as: 8051 MCU of 8 bit machines are constituted matrix type key scan with the port I/O；The dedicated core of infrared remote controller
Piece is constituted T-type key scan with the dedicated port I/O, wherein the purpose one of T-type key scan is in identical I/O port number
Under, more number of keys are obtained, purpose one is to use less I/O port number under identical number of keys demand.
Often there is the demand of driving diode (Light Emmiting Diode, LED) in the port I/O, is driven by the port I/O
LED is to indicate that chip status, infrared remote controller chip need to drive infrared ray diode.
But as shown in connection with fig. 1, electric when carrying out load driving based on existing key scan and load driving circuits trial
When the button multiplexing of road, when the output current potential of the port the I/O P0 for driving diode D1 luminous is low potential, diode D1
The potential difference at both ends is greater than the conducting current potential of diode, and electric current can substantially increase at this time, the far super general micro-control unit of the electric current
The port I/O driving capability, therefore the output current potential of the port I/O P0 is limited by the conducting current potential of diode D1, and it is above-mentioned compared with
High output current potential possibly can not be identified as inputting low potential, also cannot achieve load conduction when so as to cause operation button,
Therefore it generally will not attempt to carry out button multiplexing on load driving circuits based on existing key scan and load driving circuits.
Summary of the invention
The purpose of the embodiment of the present invention is that providing a kind of button multiplexing circuit and button multiplexing method, it can solve common feelings
The port I/O can not be shared simultaneously in the matrix type key scan or T-type key scan the problem of under condition.
First aspect present invention provides a kind of button multiplexing circuit, comprising:
Micro-control unit with key scan output end and multiplexing end；
For acting the first push-button array to be controlled load operating condition；
The key scan output being set between the key scan output end and the first connecting side of first push-button array
Circuit；
The key scan input circuit being set between the second connecting side of first push-button array and the multiplexing end；With
And
It is connected to the load circuit of the second connecting side of first push-button array,
The first input branch being connected with the multiplexing end and the second input are arranged in parallel on the key scan input circuit
Branch,
The micro-control unit is for controlling the key scan input circuit in key scan working condition to described second
The real-time current potential of connecting side is limited to make the first input branch inspection under the premise of the load is not connected by driving
The first indication signal for being used to indicate the first push-button array movement is measured, is pressed described in control when load drives working condition
Key scanning input circuit does not limit the real-time current potential of second connecting side so that the second input branch detects
It is used to indicate the second indication signal of the first push-button array movement.
The button multiplexing circuit for realizing above scheme, in key scan working condition, the key scan of micro-control unit
Input circuit limits the real-time current potential of the second connecting side of the first push-button array, to load the potential difference at both ends up to not
It to the requirement of driving load, and then loads and does not work, with the switch motion of the key in the first push-button array, realize that key is swept
The first input branch of output end difference and the second input branch connection are retouched, so that the first input branch can detecte to the first instruction
Signal, so that the second input branch can detecte to the second indication signal, to be believed according to the first indication signal and the second instruction
It number can determine whether the switch motion of key in the first push-button array.The circuit and conventional keys circuit, diode drive circuit
It compares, load conduction can also may be implemented in operation button, existing key scan and load driving circuits can be based on
It attempts to carry out button multiplexing on load driving circuits, have broad application prospects.
With reference to first aspect, in the first possible implementation of the first aspect, the first input branch road is set
It is equipped with: the current potential limiter and a comparator limited for the real-time current potential to second connecting side, the comparison
The first of device compares input terminal for input reference current potential, and the second of the comparator compares input terminal and be connected to the multiplexing end
To input the real-time current potential through limiting treated second connecting side, the comparison output end of the comparator is for exporting institute
State the second indication signal；
The second input branch road is provided with buffer amplifier and pull-up resistor, the amplification input of the buffer amplifier
End is connected to the multiplexing end, and the amplification output end of the buffer amplifier is for exporting first indication signal.
The button multiplexing circuit of above scheme is realized, when current potential limiter works, so that the real-time current potential of the second connecting side
Not less than the conducting current potential of load, so that driving load is not achieved in the potential difference for loading both ends in key scan working condition
Requirement, and then realize load do not work；And current potential limiter is when working, since the real-time current potential of the second connecting side is unrestricted
System, and then the potential difference for loading both ends reaches the requirement of driving load, and then loaded work piece；Simultaneously because comparator is by above-mentioned reality
When current potential compared with reference potential, actually or with above-mentioned real-time current potential high potential low potential for identification；Buffering is put
Big device plays the role of impedance matching, reduces distorted signals, anti-interference, while pull-up resistor effectively makes low potential become high electricity
Position has reset effect.
With reference to first aspect, in the second possible implementation of the first aspect, the micro-control unit further include:
Key scan input terminal；
The button multiplexing circuit further include: the second push-button array；
The key scan output end is connected to the first connecting side of second push-button array, and the key scan input terminal connects
It is connected to the second connecting side of second push-button array.
Realize that the button multiplexing circuit of above scheme is pressed in conjunction with key scan input terminal and the second push-button array second
When the key switch movement of key array, so that key scan input terminal is connected with key scan output end, and then it can pass through
The action state for judging the second push-button array is realized in scanning to the second push-button array, so that the button multiplexing circuit is suitable
For common matrix type key scan or T-type key scan etc..
The possible implementation of second with reference to first aspect, in the third possible implementation of first aspect
In, first push-button array and second push-button array are arranged in matrix type arrangement or T-type.
The third possible implementation with reference to first aspect, in the 4th kind of possible implementation of first aspect
In, it is 2 × 2 or 2 × 3 arrays when first push-button array is that matrix type is arranged with second push-button array；
It is 3 rows or 4 row ladder arrays when first push-button array and second push-button array are that T-type is arranged.
Realize that the button multiplexing circuit of above scheme, the matrix type key that not only can be adapted for 2 × 2 or 2 × 3 arrays are swept
It retouches, and can be adapted for the T-type key scan of 3 rows or 4 row ladder arrays.
The possible implementation of with reference to first aspect the first, in the 5th kind of possible implementation of first aspect
In, the load with conducting current potential requirement, the substantially described conducting of the reference potential are connected on the load circuit
The half of current potential.
The button multiplexing circuit for realizing above scheme is more advantageous to identification when reference potential is that the half of current potential is connected
Or actually the real-time current potential high potential low potential of the second connecting side, and then export the second more accurate indication signal.
With reference to first aspect, in the sixth possible implementation of the first aspect, the load is LED or infrared
Spool.
Realize the button multiplexing circuit of above scheme, LED or infrared tube can be used as driven load, in LED
It shines when work, the circuit may make to be suitable for the various chips with indicator light；Infrared ray is issued in infrared tube work,
The circuit may make to be suitable for infrared remote controller chip.
Second aspect of the present invention provides a kind of button multiplexing method, and the button multiplexing method is based on above-mentioned button multiplexing
Circuit, the button multiplexing method include:
In key scan working condition, key scan input circuit described in the micro-control unit controls is to second connection
The real-time current potential of side is limited detect the first input branch under the premise of the load is not connected by driving
It is used to indicate the first indication signal of the first push-button array movement,
When load drives working condition, key scan input circuit described in the micro-control unit controls does not connect to described second
The real-time current potential for connecing side is limited so that the second input branch, which detects, is used to indicate the first push-button array movement
The second indication signal.
The button multiplexing method of above scheme is realized, when the first input branch works, by the real-time of the second connecting side
Current potential is limited, so that the requirement of driving load is not achieved in the potential difference for loading both ends in key scan working condition, into
And realize that load does not work, with the opening and closing of the key switch in the first push-button array, realize key scan output end difference the
One input branch and the second input branch connection, so that the first input branch can detecte to the first indication signal, so that second
Input branch can detecte to the second indication signal, to can determine whether first according to the first indication signal and the second indication signal
The movement of push-button array.The button multiplexing method can be realized key electricity compared with conventional keys circuit, diode drive circuit
The effect that road and diode drive circuit share, the output current potential for both having solved the common port I/O are difficult to be known when being low potential
It can not share in the matrix type key scan or T-type key scan the problem of, have broad application prospects.
In conjunction with second aspect, in the first possible implementation of the second aspect, the micro-control unit is in key
Under scanning work state, set input function for the multiplexing end, open the pull-up resistor, the current potential limiter and
The comparator controls the key scan output end and periodically exports high low potential so that the first input branch detects
The button operation situation of first push-button array and second push-button array is examined in first indication signal, realization
It surveys,
Working condition is driven in load, sets output function for the multiplexing end, closes the pull-up resistor, current potential limit
Device processed and the comparator control the multiplexing end output low potential so that there are button operations in first push-button array
When, second indication signal is detected by the second input branch, realizes the conducting of the load.
Realize that the button multiplexing method of above scheme can when the first push-button array and the second push-button array are acted
To be multiplexed the output potential change of end and key scan output end in each period by comparing, to judge the first push-button array
And second push-button array action situation.
In conclusion the embodiment of the present invention has the advantages that
First, by increasing current potential limiter and comparator, compared with conventional keys circuit, diode drive circuit, Neng Goushi
The effect that existing key circuit and diode drive circuit share, so that the button multiplexing circuit is not only suitable for matrix type key scan
It is applicable in T-type key scan again, application range is wider；
Second, play the role of impedance matching by increasing buffer amplifier, reduce distorted signals, anti-interference, on increasing
Pull-up resistor effectively makes low potential become high potential, has reset effect.
Detailed description of the invention
Fig. 1 is the circuit diagram of the prior art in background of invention；
Fig. 2 is the schematic diagram of the embodiment of the present invention；
Fig. 3 is the structural schematic diagram of the first concrete application example of the embodiment of the present invention；
Fig. 4 is the key scan time diagram of the first concrete application example of the embodiment of the present invention；
Fig. 5 is the structural schematic diagram of the second concrete application example of the embodiment of the present invention；
Fig. 6 is the key scan time diagram of the second concrete application example of the embodiment of the present invention.
Appended drawing reference: 1, micro-control unit；11, key scan output end；12, key scan input terminal；13, it is multiplexed end；
14, the first input branch；141, current potential limiter；142, comparator；15, the second input branch；151, buffer amplifier；152,
Pull-up resistor；2, the first push-button array；3, load circuit；4, the second push-button array.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
The embodiment of the invention provides a kind of button multiplexing circuits, in conjunction with shown in Fig. 2 and Fig. 3, comprising: have key scan
Output end 11 and the micro-control unit 1 for being multiplexed end 13；For acting the first key battle array to be controlled load operating condition
Column 2；The key scan output circuit being set between key scan output end 11 and the first connecting side of the first push-button array 2；
The key scan input circuit being set between the second connecting side of the first push-button array 2 and multiplexing end 13；And it is connected to
The load circuit 3 of second connecting side of one push-button array 2 has been arranged in parallel on key scan input circuit and has been connected with multiplexing end 13
First input branch 14 and second input branch 15, micro-control unit 1 be used in key scan working condition control button
Scanning input circuit limits to make first under the premise of load is not connected by driving the real-time current potential of the second connecting side
Input branch 14 detects the first indication signal for being used to indicate the movement of the first push-button array 2, when load drives working condition
Control button scanning input circuit does not limit the real-time current potential of the second connecting side so that the second input branch 15 detects
It is used to indicate the second indication signal of the first push-button array 2 movement.
In key scan working condition, the key scan input circuit of micro-control unit 1 is to the of the first push-button array 2
The real-time current potential of two connecting sides is limited, so that the requirement of driving load is not achieved in the potential difference for loading both ends, and then is loaded
It does not work, with the switch motion of the key in the first push-button array 2, realizes the difference of key scan output end 11 first input branch
Road 14 is connected to the second input branch 15, so that the first input branch 14 can detecte to the first indication signal, so that second is defeated
Entering branch 15 can detecte to the second indication signal, to can determine whether first according to the first indication signal and the second indication signal
The switch motion of key in push-button array 2.The circuit can grasped compared with conventional keys circuit, diode drive circuit
Make that load conduction also may be implemented when key, load drive can be carried out based on existing key scan and load driving circuits trial
Button multiplexing on dynamic circuit, has broad application prospects.
The current potential limiter limited for the real-time current potential to the second connecting side is provided on first input branch 14
141 and a comparator 142, the first of comparator 142 compares input terminal for input reference current potential, and the second of comparator 142
Compare input terminal and is connected to multiplexing end 13 to input the real-time current potential through limiting treated the second connecting side, comparator 142
Compare output end for export the second indication signal；Buffer amplifier 151 and pull-up electricity are provided on second input branch 15
Resistance 152, the amplification input terminal of buffer amplifier 151 are connected to multiplexing end 13, and the amplification output end of buffer amplifier 151 is for defeated
First indication signal out.
When current potential limiter 141 works, so that conducting current potential of the real-time current potential of the second connecting side not less than load, thus
In key scan working condition, the requirement of driving load is not achieved in the potential difference for loading both ends, and then realizes that load does not work；
And current potential limiter 141 since the real-time current potential of the second connecting side is unrestricted, and then loads the potential difference at both ends when not working
Reach the requirement of driving load, and then loaded work piece；Simultaneously because comparator 142 carries out above-mentioned real-time current potential and reference potential
Comparison, actually or with above-mentioned real-time current potential high potential low potential for identification；Buffer amplifier 151 plays impedance matching
Effect reduces distorted signals, anti-interference, while pull-up resistor 152 effectively makes low potential become high potential, has and resets effect
Fruit.
Micro-control unit 1 further include: key scan input terminal 12；Button multiplexing circuit further include: the second push-button array 4；
Key scan output end 11 is connected to the first connecting side of the second push-button array 4, key scan input terminal 12 be connected to second by
Second connecting side of key array 4.In conjunction with key scan input terminal 12 and the second push-button array 4, in the key of the second push-button array 4
When switch motion, so that key scan input terminal 12 is connected with key scan output end 11, and then can be by pressing to second
The action state for judging the second push-button array 4 is realized in the scanning of key array 4, so that the button multiplexing circuit is suitable for often
Matrix type key scan or T-type key scan for seeing etc..
First push-button array 2 and the second push-button array 4 are arranged in matrix type, and specially 2 × 3 arrays, in other implementations
It can also be 2 × 2 arrays in example.So that the button multiplexing circuit, can be adapted for the matrix type key of 2 × 2 or 2 × 3 arrays
Scanning, stable, error rate is low.
Load is LED, and load can also be infrared tube in other embodiments, and LED or infrared tube can be used as
Driven load shines in LED operation, and the circuit may make to be suitable for the various chips with indicator light；In infrared ray
Pipe issues infrared ray when working, and the circuit may make to be suitable for infrared remote controller chip.
The load with conducting current potential requirement is connected on load circuit 3, the half of current potential is substantially connected in reference potential.
When reference potential is that the half of current potential is connected, actually or it is more advantageous to the real-time current potential high potential for identifying the second connecting side
Low potential, and then export the second more accurate indication signal.Such as system power supply VDD is 3.0V, the conducting current potential Von of load
When for 0.7V, can design basis current potential Vref be VDD-Von/2=3.0-0.7/2=2.65V；When real-time current potential is greater than 2.65V
It is identified as high potential, real-time current potential is identified as low potential when being less than 2.65V.
Below with reference to content shown in Fig. 3-6, the explanation of two concrete application examples is carried out.
In conjunction with shown in Fig. 3 and Fig. 4, by taking matrix type arrangement of the key switch of the second push-button array 4 in 2 × 3 as an example.Key
There are two the port I/O and respectively PO1 and PO2 for the setting of scanning output end 11, and there are two the ends I/O for the setting of key scan input terminal 12
Mouth and respectively PI1 and PI2, the port I/O at multiplexing end 13 are PO3, and there are two be respectively for the key switch of the first push-button array 2
K5 and K6, the key switch of the second push-button array 4 is there are four being respectively K1, K2, K3 and K4, and key switch K1 is set on PI1 and PO2
Between, key switch K2 is set between PI1 and PO1, and key switch K3 is set between PI2 and PO2, and key switch K4 is set to PI2
Between PO1.
When PO1 is set as low potential, PO2 is set as high potential, since whether scanning key K1, K2 press；When PO1 is arranged
For high potential, PO2 is set as low potential, since whether scanning key switch K3, K4 press.
When key scan, PO3 exports high potential, opens pull-up resistor 152, opens current potential limiter 141 and comparator
142, load does not work.
Timing diagram in Fig. 4 is by taking key switch K5 is pressed as an example, if key switch K5 is pressed, PO2 and PO3 are short by K5
It connects.When period A, PO1 exports low potential, and PO2 exports high potential, and PI1, PI2 and PO3 detect input high potential, it is known that K2,
K4, K6 are not pressed；When period B, PO1 exports high potential, and PO2 exports low potential, and PI1, PI2 detect input high potential,
PO2 and PO3 are shorted by K5, driving can be not achieved and want because of the restriction effect of current potential limiter 141, the voltage difference for loading both ends
It asks, load will not work (i.e. LED does not shine), but pass through the effect of comparator 142, then it can detect that PO3 inputs low potential,
It can determine that under K5.
In conjunction with shown in Fig. 5 and Fig. 6, the difference is that, the first push-button array 2 is pressed with second with above-mentioned concrete application example
The T-shaped arrangement of key array 4 and specially 4 row ladder arrays, can also be 3 row ladder arrays in other embodiments.So that should
Button multiplexing circuit can be adapted for the T-type key scan of 3 rows or 4 row ladder arrays, and stable, and error rate is low.
In conjunction with shown in Fig. 5 and Fig. 6, by taking the key switch of the second push-button array 4 is in the T-type arrangement of 4 row ladder arrays as an example.
Key scan output end 11 is provided with the port I/O and is P1, and the setting of key scan input terminal 12 is there are three the port I/O and divides
Not Wei P2, P3 and P4, the port I/O at multiplexing end 1313 is P5, the key switch of the first push-button array 2 there are four be respectively K7,
K8, K9 and K10, there are six respectively K1, K2, K3, K4, K5 and K6, key switch K1 to set for the key switch of the second push-button array 4
Between P1 and P2, key switch K2 is set between P1 and P3, and key switch K3 is set between P2 and P3, and key switch K4 is set to
Between P1 and P4, key switch K5 is set between P2 and P4, and key switch K6 is set between P3 and P4.
When key scan, PO5 exports high potential, opens pull-up resistor 152, opens current potential limiter 141 and comparator
142, load does not work.
Timing diagram in Fig. 6 is by taking key switch K8 is pressed as an example, if key K8 is pressed, P2 and P5 are shorted by K7.Period A
When, P1 exports low potential, and P2, P3, P4 and P5 export high potential；When period C, P3 exports low potential, and P1, P2, P4 and P5 are equal
Export high potential；When period D, P4 exports low potential, and P1, P2, P3 and P5 export high potential；In period A, C, D, P5 is not
Detect low potential；When period B, P2 exports low potential, and P1, P3, P4 export high potential, and P2 and P5 are shorted by K8, can be because of electricity
The restriction effect of position limiter 141, the voltage difference for loading both ends are not achieved driving and require, and load will not work, and (i.e. LED is not sent out
Light), but pass through the effect of comparator 142, then it can detect that P5 inputs low potential, that is, can determine that under K8.
A kind of button multiplexing method, in conjunction with shown in Fig. 3 or Fig. 5, which is based on two described in embodiment
Kind concrete application example, button multiplexing method include: in key scan working condition, and the scanning of 1 control button of micro-control unit is defeated
Enter circuit to limit to make the first input branch under the premise of load is not connected by driving the real-time current potential of the second connecting side
Road 14 detects the first indication signal for being used to indicate the movement of the first push-button array 2, when load drives working condition, microcontroller
1 control button of unit scanning input circuit does not limit the real-time current potential of the second connecting side so that the second input branch 15 is examined
Measure the second indication signal for being used to indicate the movement of the first push-button array 2.
When first input branch 14 works, limited by the real-time current potential to the second connecting side, to be swept in key
When retouching working condition, the requirement of driving load is not achieved in the potential difference for loading both ends, and then realizes that load does not work, with first
First input branch 14 of the difference of key scan output end 11 and the second input are realized in the opening and closing of key switch in push-button array 2
Branch 15 is connected to, so that the first input branch 14 can detecte to the first indication signal, the second input branch 15 is examined
The second indication signal is measured, to be that can determine whether moving for the first push-button array 2 according to the first indication signal and the second indication signal
Make.The button multiplexing method can also may be implemented compared with conventional keys circuit, diode drive circuit in operation button
Load conduction can be attempted to carry out button multiplexing on load driving circuits based on existing key scan and load driving circuits,
It has broad application prospects.
Micro-control unit 1 is set as input function under key scan working condition, by multiplexing end 13, opens pull-up resistor
152, current potential limiter 141 and comparator 142, control button scanning output end 11 periodically export high low potential so that first
Input branch 14 detects the first indication signal, realizes the button operation situation to the first push-button array 2 and the second push-button array 4
It is detected；Working condition is driven in load, sets output function for multiplexing end 13, closes pull-up resistor 152, current potential limitation
Device 141 and comparator 142, control multiplexing end 13 export low potential, there are when button operation, to pass through in the first push-button array 2
Second input branch 15 detects the second indication signal, realizes the conducting of load.
It, can be by comparing multiplexing end in each period when the first push-button array 2 and the second push-button array 4 are acted
13 and key scan output end 11 output potential change, to judge the movement of the first push-button array 2 and the second push-button array 4
Situation.
Embodiments described above does not constitute the restriction to the technical solution protection scope.It is any in above-mentioned implementation
Made modifications, equivalent substitutions and improvements etc., should be included in the protection model of the technical solution within the spirit and principle of mode
Within enclosing.
Claims (9)
1. a kind of button multiplexing circuit characterized by comprising
Micro-control unit (1) with key scan output end (11) and multiplexing end (13)；
The first push-button array (2) for acting to be controlled load operating condition；
The key being set between the key scan output end (11) and the first connecting side of first push-button array (2) is swept
Retouch output circuit；
The key scan input electricity being set between the second connecting side of first push-button array (2) and multiplexing end (13)
Road；And
It is connected to the load circuit (3) of the second connecting side of first push-button array (2),
Be arranged in parallel on the key scan input circuit with it is described multiplexing end (13) be connected first input branch (14) and
Second input branch (15),
The micro-control unit (1) is for controlling the key scan input circuit in key scan working condition to described the
The real-time current potential of two connecting sides is limited to make the first input branch under the premise of the load is not connected by driving
(14) the first indication signal for being used to indicate the first push-button array (2) movement is detected, when load drives working condition
The key scan input circuit is controlled not limit the real-time current potential of second connecting side so that second input
Branch (15) detects the second indication signal for being used to indicate the first push-button array (2) movement.
2. button multiplexing circuit according to claim 1, which is characterized in that
The current potential limited for the real-time current potential to second connecting side is provided in first input branch (14)
Limiter (141) and a comparator (142), the first of the comparator (142) compare input terminal for input reference electricity
Position, the second of the comparator (142) compare input terminal and are connected to the multiplexing end (13) to input through being limited treated institute
The real-time current potential of the second connecting side is stated, the comparison output end of the comparator (142) is for exporting second indication signal；
It is provided with buffer amplifier (151) and pull-up resistor (152) in second input branch (15), the buffering is put
The amplification input terminal of big device (151) is connected to the multiplexing end (13), and the amplification output end of the buffer amplifier (151) is used for
Export first indication signal.
3. button multiplexing circuit according to claim 1, which is characterized in that
The micro-control unit (1) further include: key scan input terminal (12)；
The button multiplexing circuit further include: the second push-button array (4)；
The key scan output end (11) is connected to the first connecting side of second push-button array (4), the key scan
Input terminal (12) is connected to the second connecting side of second push-button array (4).
4. button multiplexing circuit according to claim 3, which is characterized in that first push-button array (2) and described the
Two push-button arrays (4) are arranged in matrix type or T-type arrangement.
5. button multiplexing circuit according to claim 4, which is characterized in that
It is 2 × 2 or 2 × 3 times when first push-button array (2) and second push-button array (4) are that matrix type is arranged
Column；
It is 3 rows or 4 row ladder arrays when first push-button array (2) and second push-button array (4) are that T-type is arranged.
6. button multiplexing circuit according to claim 2, which is characterized in that being connected on the load circuit (3) has
The load that current potential requires, the half of the substantially described conducting current potential of the reference potential is connected.
7. button multiplexing circuit according to claim 1, which is characterized in that the load is LED or infrared tube.
8. a kind of button multiplexing method, which is characterized in that the button multiplexing method is based on such as any one of claim 2-7 institute
The button multiplexing circuit stated, the button multiplexing method include:
In key scan working condition, the micro-control unit (1) controls the key scan input circuit to described second
The real-time current potential of connecting side is limited to make the first input branch under the premise of the load is not connected by driving
(14) the first indication signal for being used to indicate the first push-button array (2) movement is detected,
When load drives working condition, the micro-control unit (1) controls the key scan input circuit not to described the
The real-time current potential of two connecting sides is limited so that second input branch (15) detects and is used to indicate first key
Second indication signal of array (2) movement.
9. button multiplexing method according to claim 8, which is characterized in that
The micro-control unit (1) is set as input function under key scan working condition, by the multiplexing end (13), opens
The pull-up resistor (152), the current potential limiter (141) and the comparator (142) control the key scan output
End (11) periodically exports high low potential so that first input branch (14) detects first indication signal, realization pair
The button operation situation of first push-button array (2) and second push-button array (4) is detected,
Load drive working condition, set output function for the multiplexing end (13), close the pull-up resistor (152),
The current potential limiter (141) and the comparator (142) control the multiplexing end (13) and export low potential described the
One push-button array (2) detects second indication signal by second input branch (15) there are when button operation, real
The conducting of the existing load.
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| CN201810377211.5A CN110401452B (en) | 2018-04-25 | 2018-04-25 | Key multiplexing circuit and key multiplexing method thereof |
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| CN201810377211.5A CN110401452B (en) | 2018-04-25 | 2018-04-25 | Key multiplexing circuit and key multiplexing method thereof |
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| CN110401452B CN110401452B (en) | 2024-04-16 |
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