CN202600109U - Button detection circuit, filter circuit and external equipment button detection chip - Google Patents
Button detection circuit, filter circuit and external equipment button detection chip Download PDFInfo
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Abstract
The utility model discloses a button detection circuit. The button detection circuit comprises the components as following: an external equipment button detection chip, which receives the button signal of a line control apparatus, carries out digital sampling to the button signal through a filter circuit, and outputs the digital logical signal of the corresponding button according to the sampling result; and an audio frequency coding and decoding device, which determines the pressed button according to the digital logical signal and executes a corresponding function. The utility model simultaneously discloses the filter circuit and the external equipment button detection chip. According to the scheme provided in the utility model, a special-purpose chip or complex software codes are unnecessary to be used on a line control device or electronic equipment, a noise interference signal in the button signal is prevented, the pressed button can be accurately detected, the filter circuit is integrated in the external equipment button detection chip, the space of a printed circuit board is saved, manufacture cost is minimized, and product design is convenient.
Description
Technical Field
The utility model relates to an electronic equipment's signal detection technique especially relates to a button detection circuitry, filter circuit and external equipment button detect chip.
Background
With the rapid development of electronic technology, many portable electronic devices such as walkmans, Compact Disc (CD) players, palm computers, and mobile phones provide a line control device, and a user can conveniently operate the electronic devices through the line control device, for example: the control of music playing, phone answering, volume control and the like are realized.
The drive-by-wire device is usually provided with a plurality of keys to realize different control functions, and the electronic equipment identifies that a certain key is pressed by detecting a key signal. However, in practical applications, the key signal generally contains a noise interference signal, and in order to accurately perform key detection and avoid key detection error detection and missing detection caused by the noise interference signal, a dedicated key signal sending chip needs to be arranged on the line control device in general, and a matched key signal receiving chip is arranged on the electronic device.
As shown in fig. 1, a mobile device of Apple (Apple) is provided with a wire-controlled headset, which is provided with a dedicated digital signal transmitting chip IC 1 for recognizing a pressed key and generating a corresponding digital signal to the mobile device, and a dedicated digital signal receiving chip IC2 also provided at a mobile device side for receiving the digital signal and transmitting the digital signal as a control signal to an Audio Codec (Audio Codec)32, and the Audio Codec 32 controls a left channel signal (L _ SPKR) and a right channel signal (R _ SPKR) transmitted to the headset according to the control signal. The method can avoid the key detection error detection and omission caused by noise interference signals, but special chips are required to be arranged on the line control equipment and the electronic equipment, thereby greatly increasing the manufacturing cost.
In addition, the electronic equipment filters the key signal through software, and can also avoid key detection error detection and omission caused by noise interference signals, but complex software codes for filtering are needed, the code processing amount of an operating system of the electronic equipment is increased, and product design is not facilitated.
SUMMERY OF THE UTILITY MODEL
In view of this, in order to solve the problem that the prior art needs to use a dedicated chip or a complex software code to avoid containing noise interference signals in the key signal, the present invention provides a key detection circuit, a filter circuit and an external device key detection chip.
In order to achieve the above purpose, the technical scheme of the utility model is realized like this:
the utility model provides a pair of filter circuit, filter circuit is: and the filter circuit is used for carrying out digital sampling on the key signal, determining a pressed key according to a sampling result and outputting a digital logic signal corresponding to the key.
The utility model provides a pair of external equipment button detects chip, this chip includes:
the filter circuit is used for digitally sampling the key signals, determining the pressed key according to the sampling result and outputting a digital logic signal corresponding to the key;
and receiving the digital logic signal output by the filter circuit, and sending the digital logic signal to the digital logic circuit of the audio codec through an inter-integrated circuit (I2C) bus.
The utility model provides a pair of button detection circuitry, this circuit includes:
the external equipment key detection chip receives a key signal of the wire control device, performs digital sampling on the key signal through the filter circuit, and outputs a digital logic signal corresponding to a key according to a sampling result;
and determining the pressed key according to the digital logic signal, and executing the audio coding and decoding of the corresponding function.
The utility model provides a button detection circuitry, filter circuit and external equipment button detect chip, this detection circuitry includes: the external equipment key detection chip receives a key signal of the wire control device, performs digital sampling on the key signal through the filter circuit, and outputs a digital logic signal corresponding to a key according to a sampling result; determining the pressed key according to the digital logic signal, and executing audio coding and decoding of corresponding functions; therefore, the noise interference signal in the key signal can be avoided without using a special chip or a complex software code on the wire control device and the electronic equipment, and the pressed key can be accurately detected; in addition, the filter circuit is integrated in the external equipment key detection chip, so that the space of a Printed Circuit Board (PCB) can be saved, the manufacturing cost is reduced, and the product design is facilitated.
Drawings
FIG. 1 is a schematic diagram of a detection circuit for a wire-controlled earphone button in the prior art;
fig. 2 is a schematic diagram of a key detection circuit implemented by an embodiment of the present invention;
FIG. 3 is a schematic diagram of a filter circuit of the on-line control device according to the embodiment of the present invention when three buttons need to be detected;
fig. 4 is a schematic flow chart of the embodiment of the present invention for implementing a key detection method.
Detailed Description
The basic idea of the utility model is that: accessing a key signal of the wire control device into an external equipment key detection chip of the electronic equipment; the external equipment key detection chip carries out digital sampling on the key signal through the filter circuit and outputs a digital logic signal corresponding to the key to the audio codec according to a sampling result; and the audio codec determines the pressed key according to the digital logic signal and executes a corresponding function.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
An embodiment of the utility model provides a button detection circuitry, as shown in fig. 2, this circuit includes: an external device key detection chip 31, an audio codec 32; wherein,
the external device key detection chip 31 is configured to receive a key signal of the line control device, perform digital sampling on the key signal through the filter circuit, and output a digital logic signal of a corresponding key to the audio codec 32 according to a sampling result;
and the audio codec 32 is configured to determine the pressed key according to the digital logic signal and execute the corresponding function.
The external device key detection chip 31 includes: filter circuit 311, digital logic circuit 312, I2C bus 313; wherein,
the filter circuit 311 is configured to perform digital sampling on the key signal, determine a pressed key according to a sampling result, and output a digital logic signal corresponding to the key to the digital logic circuit 312;
the digital logic circuit 312, configured to receive the digital logic signal output by the filter circuit, and send the digital logic signal to the audio codec 32 through the I2C bus 313;
the external device key detection chip 31 further includes a Mic Switch (Mic _ Switch)314 configured to transmit a voice signal to the audio codec 32 when the Mic key is pressed;
the filter circuit 311 includes: a reference voltage supply circuit 3111, a comparator sampling circuit 3112, a sampling result register 3113, and a logic processing circuit 3114; wherein,
a reference voltage supply circuit 3111 configured to supply a reference voltage of each key to the comparator sampling circuit 3112;
a comparator sampling circuit 3112 configured to set comparators equal to the number of keys, each of the comparators comparing a reference voltage of each of the keys with a voltage of a key signal, wherein the comparator triggered by the key signal transmits a trigger signal to the sampling result register 3113;
specifically, the reference voltage of each key in the comparator sampling circuit 3112 is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register 3113;
a sampling result register 3113 configured to receive a trigger signal at an output terminal of each comparator in the comparator sampling circuit 3112, count the output terminal by a pulse counter according to the trigger condition of each comparator, and send the count result of each output terminal to the logic processing circuit 3114;
a logic processing circuit 3114 configured to determine a pressed key according to the count result of each output port, and output a digital logic signal corresponding to the key;
specifically, the logic processing circuit 3114 searches for an output port whose count result first reaches a preset threshold, determines that a key corresponding to the output port is a pressed key, and outputs a digital logic signal corresponding to the key.
The operation of the comparator sampling circuit 3112, the sampling result register 3113 and the logic processing circuit 3114 is further described by specific examples.
When the line control device has three keys to be detected, three comparators are disposed in the comparator sampling circuit 3112, as shown in fig. 3, positive input terminals of the three comparators respectively receive reference voltages of the three keys, wherein the positive input terminal of the first comparator CP1 receives the reference voltage Vref1 of the first key, the positive input terminal of the second comparator CP2 receives the reference voltage Vref2 of the second key, the positive input terminal of the third comparator CP3 receives the reference voltage Vref3 of the third key, values of the Vref1, Vref2, and Vref3 are determined by resistance values of series resistors of the keys, and it is assumed that Vref1 < Vref2 < Vref 3; the negative input ends of the three comparators receive a key signal KPS (key Press signal), when the voltage of KPS is less than Vref1, the three comparators are all triggered to generate high-level trigger signals to the sampling result register 3113, and the sampling result register 3113 adds 1 to the value of the pulse counter of the first output port Out 1; when the KPS voltage is greater than Vref1 and less than Vref2, the first comparator CP1 is not triggered, the second comparator CP2 and the third comparator CP3 are triggered, the second comparator CP2 and the third comparator CP3 generate a high-level trigger signal to the sampling result register 3113, and the sampling result register 3113 increments the pulse counter value of the second output port Out2 by 1; when the KPS voltage is greater than Vref2 and less than Vref3, the first comparator CP1 and the second comparator CP2 are not triggered, the third comparator CP3 is triggered, the third comparator CP3 generates a high-level trigger signal to the sampling result register 3113, and the sampling result register 3113 increments the pulse counter value of the third output port Out3 by 1; when the counting result of the pulse counter of the first output port Out1 reaches the preset threshold value first, it is determined that the first key is pressed, and the logic processing circuit 3114 outputs a digital logic signal corresponding to the first key, such as 01; when the counting result of the pulse counter of the second output port Out2 reaches the preset threshold value first, it is determined that the second key is pressed, and the logic processing circuit 3114 outputs a digital logic signal corresponding to the second key, for example, 10; when the counting result of the pulse counter of the third output port Out3 reaches the preset threshold value first, it is determined that the third key is pressed, and the logic processing circuit 3114 outputs a digital logic signal corresponding to the third key; the preset threshold is generally set according to the sampling rate and the sampling time of the chip on which the filter circuit is located, and may be 10 times, 28 times, 30 times, and the like; here, the larger the threshold value, the more accurate the key detection.
Based on above-mentioned button detection circuitry, the embodiment of the utility model provides a still provide an external equipment button detection chip, as shown in FIG. 2, external equipment button detection chip 31 includes: filter circuit 311, digital logic circuit 312, I2C bus 313; wherein,
the filter circuit 311 is configured to perform digital sampling on the key signal, determine a pressed key according to a sampling result, and output a digital logic signal corresponding to the key to the digital logic circuit 312;
the digital logic circuit 312, configured to receive the digital logic signal output by the filter circuit, and send the digital logic signal to the audio codec 32 through the I2C bus 313;
the external device key detection chip 31 further includes a Mic Switch (Mic _ Switch)314 configured to transmit a voice signal to the audio codec 32 when the Mic key is pressed;
the filter circuit 311 includes: a reference voltage supply circuit 3111, a comparator sampling circuit 3112, a sampling result register 3113, and a logic processing circuit 3114; wherein,
a reference voltage supply circuit 3111 configured to supply a reference voltage of each key to the comparator sampling circuit 3112;
a comparator sampling circuit 3112 configured to set comparators equal to the number of keys, each of the comparators comparing a reference voltage of each of the keys with a voltage of a key signal, wherein the comparator triggered by the key signal transmits a trigger signal to the sampling result register 3113;
specifically, the reference voltage of each key in the comparator sampling circuit 3112 is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register 3113;
a sampling result register 3113 configured to receive the trigger signal output by each comparator in the comparator sampling circuit 3112, count the output port by a pulse counter according to the trigger condition of each comparator, and send the count result of each output port to the logic processing circuit 3114;
a logic processing circuit 3114 configured to determine a pressed key according to the count result of each output port, and output a digital logic signal corresponding to the key;
specifically, the logic processing circuit 3114 searches for an output port whose count result first reaches a preset threshold, determines that a key corresponding to the output port is a pressed key, and outputs a digital logic signal corresponding to the key.
The embodiment of the present invention further provides a filter circuit, as shown in fig. 2, the filter circuit 311 is configured to perform digital sampling on the key signal, determine the pressed key according to the sampling result, and output a digital logic signal corresponding to the key;
the filter circuit 311 includes: a reference voltage supply circuit 3111, a comparator sampling circuit 3112, a sampling result register 3113, and a logic processing circuit 3114; wherein,
a reference voltage supply circuit 3111 configured to supply a reference voltage of each key to the comparator sampling circuit 3112;
a comparator sampling circuit 3112 configured to set comparators equal to the number of keys, each of the comparators comparing a reference voltage of each of the keys with a voltage of a key signal, wherein the comparator triggered by the key signal transmits a trigger signal to the sampling result register 3113;
specifically, the reference voltage of each key in the comparator sampling circuit 3112 is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register 3113;
a sampling result register 3113 configured to receive the trigger signal output by each comparator in the comparator sampling circuit 3112, count the output port by a pulse counter according to the trigger condition of each comparator, and send the count result of each output port to the logic processing circuit 3114;
a logic processing circuit 3114 configured to determine a pressed key according to the count result of each output port, and output a digital logic signal corresponding to the key;
specifically, the logic processing circuit 3114 searches for an output port whose count result first reaches a preset threshold, determines that a key corresponding to the output port is a pressed key, and outputs a digital logic signal corresponding to the key.
The utility model discloses realize button detection method, as shown in FIG. 4, this method includes following step:
step 101: accessing a key signal of the wire control device into an external equipment key detection chip of the electronic equipment;
here, the external device key detection chip includes an audio interface multi-key detection chip.
Step 102: the external equipment key detection chip carries out digital sampling on the key signal through the filter circuit and outputs a digital logic signal corresponding to the key to the audio codec according to a sampling result;
specifically, a filter circuit is integrated in the external device key detection chip, comparators with the number equal to that of the keys are arranged in the filter circuit, a first signal input end of each comparator receives a reference voltage of each key, a second signal input end of each comparator receives a key signal, each comparator generates a trigger signal when being triggered by the key signal, counting is carried out on a corresponding output port through a pulse counter according to the trigger condition of each comparator, the filter circuit determines the pressed key according to the counting result of each output port, and a digital logic signal corresponding to the key is output to a digital logic circuit in the external device key detection chip; the digital logic Circuit sends the digital logic signal to an audio codec through an Inter-Integrated Circuit (I2C) bus;
the key which is determined to be pressed according to the counting result of each output port is as follows: and inquiring an output port with a counting result reaching a preset threshold value at first, and determining that a key corresponding to the output port is a pressed key.
The implementation of this step is further illustrated by the specific examples below.
When only one key of the line control device needs to be detected, a comparator is arranged in the filter circuit, the positive input end of the comparator receives the reference voltage of the key, and the negative input end of the comparator receives a key signal; when the voltage of the key signal at the negative input end is less than the reference voltage at the positive input end, the comparator is triggered to generate a high-level trigger signal, counting is carried out at an output port through a pulse counter, when the counting result reaches a preset threshold value, the key is determined to be pressed, and a digital logic signal corresponding to the key is output, such as 11; a digital logic circuit in the external device key detection chip sends a digital logic signal to the audio codec through an I2C bus; the preset threshold is generally set according to the sampling rate and the sampling time of the chip on which the filter circuit is located, and may be 10 times, 28 times, 30 times, and the like; here, the larger the threshold value, the more accurate the key detection.
When the line control device has two keys to be detected, two comparators are arranged in the filter circuit, positive input ends of the two comparators respectively receive reference voltages of the two keys, wherein the first comparator receives the reference voltage Vref1 of the first key, the second comparator receives the reference voltage Vref2 of the second key, values of the Vref1 and the Vref2 are determined by resistance values of series resistors of the first key and the second key, and it is assumed that Vref1 is less than Vref 2; the negative input ends of the two comparators receive the key signal, when the voltage of the key signal is less than Vref1, the two comparators are triggered to generate high-level trigger signals, and the value of a pulse counter of the first output port is increased by 1; when the key signal voltage is greater than Vref1 and less than Vref2, the first comparator is not triggered, the second comparator is triggered, the second comparator generates a high-level trigger signal, and the value of a pulse counter of the second output port is increased by 1; and when the counting result of the pulse counter of the first output port reaches a preset threshold value, determining that the first key is pressed, and outputting a digital logic signal corresponding to the first key, such as 01. When the counting result of the pulse counter of the second output port reaches a preset threshold value, determining that the second key is pressed, and outputting a digital logic signal corresponding to the second key, such as 10; a digital logic circuit in the external device key detection chip sends a digital logic signal to the audio codec through an I2C bus; the preset threshold is generally set according to the sampling rate and the sampling time of the chip on which the filter circuit is located, and may be 10 times, 28 times, 30 times, and the like; here, the larger the threshold value, the more accurate the key detection.
When the line control device has three keys to be detected, three comparators are arranged in the filter circuit, positive input ends of the three comparators respectively receive reference voltages of the three keys, wherein the positive input end of the first comparator receives the reference voltage Vref1 of the first key, the positive input end of the second comparator receives the reference voltage Vref2 of the second key, the positive input end of the third comparator receives the reference voltage Vref3 of the third key, values of the Vref1, Vref2 and Vref3 are determined by resistance values of series resistors of the keys, and it is assumed that Vref1 is less than Vref2 is less than Vref 3; the negative input ends of the three comparators receive the key signal, when the voltage of the key signal is less than Vref1, the three comparators are triggered to generate high-level trigger signals, and the value of a pulse counter of the first output port is increased by 1; when the key signal voltage is greater than Vref1 and less than Vref2, the first comparator is not triggered, the second comparator and the third comparator are triggered, the second comparator and the third comparator generate a high-level trigger signal, and the value of a pulse counter of the second output port is increased by 1; when the key signal voltage is greater than Vref2 and less than Vref3, the first comparator and the second comparator are not triggered, the third comparator is triggered, the third comparator generates a high level trigger signal, and the pulse counter value of the third output port is increased by 1. When the counting result of the pulse counter of the first output port reaches a preset threshold value, determining that the first key is pressed down, and outputting a digital logic signal corresponding to the first key, such as 01; when the counting result of the pulse counter of the second output port reaches a preset threshold value, determining that the second key is pressed, and outputting a digital logic signal corresponding to the second key, such as 10; when the counting result of the pulse counter at the third output port reaches the preset threshold value, the third key is determined to be pressed, and a digital logic signal corresponding to the third key is output, such as 11; a digital logic circuit in the external device key detection chip sends a digital logic signal to the audio codec through an I2C bus; the preset threshold is generally set according to the sampling rate and the sampling time of the chip on which the filter circuit is located, and may be 10 times, 28 times, 30 times, and the like; here, the larger the threshold value, the more accurate the key detection.
When the drive-by-wire device has more than three keys to be detected, the working method of the filter circuit is the same as that described above, and no more detection examples of the keys are performed here.
Step 103: and the audio codec determines the pressed key according to the digital logic signal and executes a corresponding function.
The utility model discloses realize key signal's filtering method, this method includes: the method comprises the steps of carrying out digital sampling on a key signal of the wire control device, determining a pressed key according to a sampling result, and outputting a digital logic signal corresponding to the key.
The method further comprises the following steps: setting comparators with the same number as the keys, wherein the first signal input end of each comparator receives the reference voltage of each key respectively, and the second signal input end of each comparator receives the key signal;
the digital sampling of the key signal, the determination of the pressed key according to the sampling result and the output of the digital logic signal corresponding to the key are as follows:
each comparator compares the reference voltage of each key with the voltage of the key signal, wherein the comparator triggered by the key signal generates a trigger signal; counting at the corresponding output port through a pulse counter according to the triggering condition of each comparator, determining a pressed key according to the counting result of each output port, and outputting a digital logic signal corresponding to the key;
the key which is determined to be pressed according to the counting result of each output port is as follows: and inquiring an output port with a counting result reaching a preset threshold value at first, and determining that a key corresponding to the output port is a pressed key.
To sum up, the scheme of the utility model can avoid the noise interference signal in the key signal without using a special chip or a complex software code on the line control device and the electronic equipment, and accurately detect the pressed key; in addition, the filter circuit is integrated in the external equipment key detection chip, so that the space of the PCB can be saved, the manufacturing cost is reduced, and the product design is facilitated.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.
Claims (12)
1. A filter circuit, wherein the filter circuit is: and the filter circuit is used for carrying out digital sampling on the key signal, determining a pressed key according to a sampling result and outputting a digital logic signal corresponding to the key.
2. The filter circuit of claim 1, wherein the filter circuit comprises:
a reference voltage supply circuit for supplying reference voltages of the keys to the comparator sampling circuit;
the comparator sampling circuit is provided with comparators with the number equal to that of the keys, each comparator compares the reference voltage of each key with the voltage of the key signal, and the comparator triggered by the key signal sends a trigger signal;
receiving trigger signals output by each comparator in a comparator sampling circuit, counting at a corresponding output port through a pulse counter according to the trigger condition of each comparator, and sending the counting result of each output port to a sampling result register of a logic processing circuit;
and the logic processing circuit determines the pressed key according to the counting result of each output port and outputs a digital logic signal corresponding to the key.
3. The filter circuit according to claim 2, wherein the reference voltage of each key in the comparator sampling circuit is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register.
4. A chip for detecting keys of an external device, the chip comprising:
the filter circuit is used for digitally sampling the key signals, determining the pressed key according to the sampling result and outputting a digital logic signal corresponding to the key;
and receiving the digital logic signal output by the filter circuit, and sending the digital logic signal to the digital logic circuit of the audio codec through an inter-integrated circuit (I2C) bus.
5. The peripheral device key detection chip of claim 4, further comprising a microphone switch for transmitting a voice signal to an audio codec when a microphone key is pressed.
6. The external device key detection chip of claim 4, wherein the filter circuit comprises:
a reference voltage supply circuit for supplying reference voltages of the keys to the comparator sampling circuit;
the comparator sampling circuit is provided with comparators with the number equal to that of the keys, each comparator compares the reference voltage of each key with the voltage of the key signal, and the comparator triggered by the key signal sends a trigger signal;
receiving trigger signals output by each comparator in a comparator sampling circuit, counting at a corresponding output port through a pulse counter according to the trigger condition of each comparator, and sending the counting result of each output port to a sampling result register of a logic processing circuit;
and the logic processing circuit determines the pressed key according to the counting result of each output port and outputs a digital logic signal corresponding to the key.
7. The peripheral device key detection chip of claim 6, wherein the reference voltage of each key in the comparator sampling circuit is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register.
8. A key detection circuit, comprising:
the external equipment key detection chip receives a key signal of the wire control device, performs digital sampling on the key signal through the filter circuit, and outputs a digital logic signal corresponding to a key according to a sampling result;
and determining the pressed key according to the digital logic signal, and executing the audio coding and decoding of the corresponding function.
9. The key detection circuit of claim 8, wherein the external device key detection chip comprises:
the filter circuit is used for digitally sampling the key signals, determining the pressed key according to the sampling result and outputting digital logic signals corresponding to the key;
and receiving the digital logic signal output by the filter circuit, and sending the digital logic signal to the digital logic circuit of the audio codec through an inter-integrated circuit (I2C) bus.
10. The key detect circuit of claim 9, wherein the peripheral device key detect chip further comprises a microphone switch for transmitting a voice signal to an audio codec when a microphone key is pressed.
11. The key detect circuit of claim 9, wherein the filter circuit comprises:
a reference voltage supply circuit for supplying reference voltages of the keys to the comparator sampling circuit;
the comparator sampling circuit is provided with comparators with the number equal to that of the keys, each comparator compares the reference voltage of each key with the voltage of the key signal, and the comparator triggered by the key signal sends a trigger signal;
receiving trigger signals output by each comparator in a comparator sampling circuit, counting at a corresponding output port through a pulse counter according to the trigger condition of each comparator, and sending the counting result of each output port to a sampling result register of a logic processing circuit;
and the logic processing circuit determines the pressed key according to the counting result of each output port and outputs a digital logic signal corresponding to the key.
12. The key detect circuit of claim 11, wherein the reference voltage of each key in the comparator sampling circuit is respectively connected to the first signal input terminal of each comparator, the key signal is connected to the second signal input terminal of each comparator, and the output terminal of each comparator is connected to the sampling result register.
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| CN 201220143423 CN202600109U (en) | 2012-03-30 | 2012-03-30 | Button detection circuit, filter circuit and external equipment button detection chip |
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| CN 201220143423 CN202600109U (en) | 2012-03-30 | 2012-03-30 | Button detection circuit, filter circuit and external equipment button detection chip |
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| CN103237281A (en) * | 2013-05-08 | 2013-08-07 | 广东欧珀移动通信有限公司 | Earphone wire control circuit of mobile terminal and wire control method |
| CN103364718A (en) * | 2012-03-30 | 2013-10-23 | 快捷半导体(苏州)有限公司 | Button detection and filtering method, relevant circuit and external device button detection chip |
| CN104270160A (en) * | 2014-09-19 | 2015-01-07 | 福州瑞芯微电子有限公司 | Key detecting device and method |
| CN104330981A (en) * | 2013-07-22 | 2015-02-04 | 联想(北京)有限公司 | Key control method, electronic device and line-control device |
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