CN109462405B - Single-wire transmission key detection circuit - Google Patents
Single-wire transmission key detection circuit Download PDFInfo
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- CN109462405B CN109462405B CN201811346354.6A CN201811346354A CN109462405B CN 109462405 B CN109462405 B CN 109462405B CN 201811346354 A CN201811346354 A CN 201811346354A CN 109462405 B CN109462405 B CN 109462405B
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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
Abstract
The invention discloses a single-wire transmission key detection circuit, which is realized based on infrared remote control coding, after keys are collected, a key coding chip U1 capable of being remotely controlled by infrared codes the collected keys, then U1 modulates the codes on carrier frequency, then the codes are sent to a receiving end through a metal transmission line, and the receiving end decodes the codes after demodulation to obtain key values; the key detection method generally comprises multi-IO port detection, matrix keyboard detection and AD detection, the multi-IO port detection and matrix keyboard detection method can occupy more IO ports and use more connecting wires, the AD detection only occupies one IO port and only needs one connecting wire, but false triggering or signal acquisition is easy to occur due to interference of power supply fluctuation or line resistance error of the connecting wire.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to a single-wire transmission key detection circuit.
Background
In the prior art, the key detection modes commonly adopted include multi-IO port detection, matrix keyboard detection and AD detection.
The first multi-IO port detection mode is that one key occupies one IO port detection, more IO ports can be occupied, and more connecting lines are used; in long-distance acquisition, in which the key positions are far away from the receiving device, multiple IO detection is needed to be connected through a long-distance multiple transmission line, so that the connection lines are complicated in appearance and easy to interfere with each other;
the second matrix keyboard detection, although a plurality of IO ports are omitted compared with the first multi-IO port detection, more IO resources are occupied; in long-distance acquisition, in which the key positions are far away from the receiving device, matrix keyboard detection is also required to be connected through long-distance multiple transmission lines, so that the connection lines are complicated in appearance and easy to interfere with each other;
the third type of AD (analog-to-digital conversion) detection, while only occupying one IO port and only using one connecting wire, false triggering or signal acquisition is easy to occur due to interference of power supply fluctuation or wire resistance error of the connecting wire; while AD detection does only have one transmission line, this application cannot meet the accuracy of acquisition at all due to the excessive line resistance of the long-distance connection line and due to the external various electromagnetic wave radiation.
Disclosure of Invention
The invention provides a single-wire transmission key detection circuit which is used for overcoming the defects of the prior art that IO resources are wasted, transmission lines are more and are easy to interfere with each other, key acquisition stability is poor and the like, realizing single-wire transmission of key detection, realizing high key acquisition stability and avoiding IO resource waste.
In order to achieve the above object, the present invention provides a single-wire transmission key detection circuit, comprising:
a key transmitting section comprising:
the key circuit is used for connecting the keys to be tested together;
the input port of the key coding chip is connected with the key circuit, codes according to a key signal output by a key to be tested triggered in the key circuit to obtain coding information, and the coding information is output in the form of a digital signal;
the carrier circuit receives the coded information and modulates the coded information onto a high-frequency carrier to form a carrier signal and outputs the carrier signal to the key coding chip;
the driving circuit is connected with the output port of the key coding chip and receives and transmits the carrier signal when the key to be tested is started;
a key receiving section comprising:
the demodulation circuit is connected with the driving circuit through a metal connecting wire, receives the carrier signal, filters high-frequency carriers in the carrier signal and outputs coding information;
a processor for receiving the encoded information and decoding the encoded information to obtain a key value; and judging whether the key to be tested triggered in the key circuit is qualified or not according to the key value.
The invention provides a single-line transmission key detection circuit, which comprises a key signal transmitting part and a key signal receiving part, wherein the key signal transmitting part encodes an acquired key signal through a key encoding chip to generate encoding information in the form of a digital signal, a carrier circuit is triggered to generate a high-frequency carrier wave at the same time, the key encoding chip modulates the encoded key signal onto the high-frequency carrier wave to form a carrier signal, the carrier signal is output into a driving circuit through the key encoding chip, the driving circuit performs level conversion and signal shaping on the key signal, the carrier signal is then transmitted into a key signal receiving part through a metal transmission line, the demodulation circuit performs carrier frequency removal processing on the input carrier signal and then outputs the encoding information of the key signal to a processor unit, and the processor unit decodes the encoding information to obtain a key value. Compared with the prior art, the key coding chip can simultaneously code and modulate a plurality of detected keys and output the keys, so that IO resource waste caused by occupation of a plurality of IO ports is avoided; then, the invention utilizes a single wire to transmit a plurality of key signals, thereby avoiding the complicated circuit caused by the transmission of a plurality of transmission lines and avoiding the problem of easy interference among the plurality of transmission lines; in addition, the key coding chip codes the key signals into digital signals, so that the signals are more stable in the transmission process, and meanwhile, the driving circuit performs level conversion and signal shaping on the carrier signals, improves the driving capability of the signals, and meanwhile, improves the signal transmission distance, so that the signals are more stable in the long-distance transmission process.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a remote key detection circuit of a single-wire transmission key detection circuit according to the present invention;
fig. 2 is a schematic diagram of a receiving circuit of a single-wire transmission key detection circuit according to the present invention.
Reference numerals illustrate: 1: key signal transmitting section, 10: key circuit, 101: key to be measured, 11: drive circuit, 111: first resistor, 112: second resistor, 113: emitting transistor, 12: key code chip, 100: carrier circuit, 13: crystal, 14: first capacitance, 15: second capacitance, 16: third capacitance, 17: transmitting a direct current power supply, 2: key signal receiving section, 21: third resistor, 22: fourth resistance, 23: receiving transistor, 24: fourth capacitance, 3: demodulation circuit, 31: processor unit, 4: a direct current power supply is received and the power supply is switched off,
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
Referring to fig. 1, the present invention provides a single-wire transmission key detection circuit, including:
a key signal transmitting section 1 including a key circuit 10, a key code chip 12, a carrier circuit 100, a driving circuit 11; wherein: the key circuit 10 comprises a plurality of keys 101 to be tested which are connected in parallel; the key coding chip 12, the input port is connected with the key circuit 10, and codes according to the key signal output by the key 101 to be tested triggered in the key circuit 10 to obtain coding information, and the coding information is output in the form of digital signals; the coded information is binary number; a carrier circuit 100 for receiving the encoded information and modulating the encoded information onto a high-frequency carrier to form a carrier signal, and outputting the carrier signal to the key code chip 12; the driving circuit 11 is connected with the output port of the key coding chip, receives and amplifies the level of the carrier signal when the key to be tested is started and outputs the carrier signal;
the key coding chip 12 codes the acquired key signals to generate binary coding information, the trigger chip 13 generates high-frequency carrier frequency, the key coding chip 12 modulates the coded binary coding information to the high-frequency carrier frequency, the carrier signals are output from pins of the key coding chip 12 and enter the driving circuit 11, the driving circuit 11 is a primary inverter and is used for inverting and amplifying the carrier signals, and meanwhile, the driving circuit 11 also performs level amplification and signal inverting shaping on the key signals;
the key coding chip 12 can simultaneously code and modulate the detected plurality of keys and output the key signals, so that IO resource waste caused by occupation of a plurality of IO ports is avoided, and in addition, the key coding chip 12 codes the key signals into digital signals, so that the signals are more stable in the transmission process; the driving circuit 11 performs level conversion and signal shaping on the key signals, so that the driving capability of the signals can be improved, and meanwhile, the signal transmission distance is increased, so that the signals are more stable in the long-distance transmission process;
referring to fig. 2, the key signal receiving section 2 includes a demodulation circuit 3 and a processor 31, the demodulation circuit 3 is connected to the driving circuit 11 through a metal connection line, receives the carrier signal, filters out a high-frequency carrier in the carrier signal, and outputs encoded information; the demodulation circuit 3 is a two-stage inverter and is also a comparator; the processor 31 receives the encoded information and decodes the encoded information to obtain a key value; and judging whether the key 101 to be tested triggered in the key circuit 10 is qualified or not according to the key value.
After the key signal is transmitted into the receiving circuit through the metal transmission line, the receiving circuit carries out carrier frequency removal processing on the input key signal, the demodulating circuit 3 carries out secondary phase inversion on the key signal, amplifies the key signal and then inputs the key signal into the processor 31, the processor 31 further comprises a decoding chip, and the decoding chip decodes the coded information to obtain a key value; the processor 31 judges whether the triggered key 101 to be tested is qualified or not according to the key value.
The single-wire transmission key detection circuit is realized based on infrared remote control coding, after keys are collected, a key coding chip U1 capable of being remotely controlled by infrared codes the collected keys, then U1 modulates the codes on carrier frequency, and then the codes are sent to a receiving end through a metal transmission line, and the receiving end decodes the codes after demodulation to obtain key values; the carrier signal is transmitted into the demodulation circuit 3 through the metal transmission line, so that the complex line caused by the transmission of multiple transmission lines is avoided, and the problem of easy mutual interference caused by the multiple transmission lines is avoided. The key detection method generally comprises multi-IO port detection, matrix keyboard detection and AD detection, the multi-IO port detection and matrix keyboard detection method can occupy more IO ports and use more connecting wires, the AD detection only occupies one IO port and only needs one connecting wire, but false triggering or signal acquisition is easy to occur due to interference of power supply fluctuation or line resistance error of the connecting wire.
The key circuit 10 comprises at least one branch circuit, and each branch circuit comprises a plurality of keys 101 to be tested which are connected in parallel; one end of each of the branch circuits is connected to one input port of the key code chip 12, and the other end of the branch circuit is connected to one code output port of the key code chip 12. The key code chip 12 comprises three coding modes; the ports of each coding mode are connected to a group of sub-circuits, when any key 101 to be tested is pressed, the key coding chip 12 generates a series of pulse codes (coding information), the coded pulses modulate the high-frequency carrier wave generated by the carrier circuit 100 in pulse amplitude to form a carrier signal, and the carrier signal is amplified and inverted by the driving circuit 11 and then transmitted to the key signal receiving part 2 through a single metal wire. The keyboard is in the form of a matrix scanning keyboard, each key is connected to at least one row and one column, the key coding chip 12 sends out a time-division row scanning signal, and when the key is pressed, the key coding chip reads the corresponding column signal level change, so that the judgment of which key is pressed is made.
The carrier circuit 100 includes: a crystal 13, a first capacitor 14, a second capacitor 15; the crystal 13 is used for generating a high-frequency carrier wave, and two ends of the crystal are respectively connected to two ports of the key code chip; one end of the first capacitor 14 is connected to one end of the crystal 13, and the other end of the first capacitor is connected to the other port of the key code chip 12 after being connected with the second capacitor 15; one end of the second capacitor 15 is connected with the first capacitor, and the other end of the second capacitor is connected with the other end of the crystal; one end of the first capacitor 14 connected with the second capacitor 15 is grounded. The first capacitor 14 and the second capacitor 15 are resonance capacitors of the crystal 13, and are capacitors required for meeting the normal operation of the crystal.
Preferably, the driving circuit 11 includes a first resistor 111, a second resistor 112 and a transmitting triode 113, where the driving circuit 11 is a primary inverter for primary inverting the carrier signal, and meanwhile, the driving circuit 11 performs level conversion and signal shaping on the key signal, so as to improve the driving capability of the signal, and meanwhile, improve the signal transmission distance, so that the signal is more stable in the long-distance transmission process; the key code chip 12 emits a code waveform, and when the chip 12 emits a low level, the transistor 113 emits a high level due to the fact that the base voltage is low, and therefore the collector-emitter of the tube is not conducted, so that the driving circuit 11 emits a high level. When the key code chip 12 sends out high level, the base voltage of the triode 113 is high level, and the collector-emitter of the triode 12 is conducted, so that the driving circuit 11 sends out low level. Since the signal driving is performed by the encoding chip 12 without the driving circuit 11, the high-level and low-level signals become power and ground driving after the driving circuit 11 is provided, which is equivalent to the improvement of driving capability.
One end of the first resistor 111 is connected to the key code chip 12, and the other end is connected to the base of the emitting triode 113; one end of the second resistor 112 is connected to the positive electrode of the transmitting DC power supply 17 and the key code chip 12 at the same time, and the other end is connected to the collector of the transmitting triode 113; the emitter of the emitting triode 113 is connected to the cathode of the emitting direct current power supply 17; one end of the third capacitor 16 is connected with the positive electrode of the transmitting direct current power supply 17, and the other end of the third capacitor is grounded. The third capacitor 16 is used for filtering the power supply, and because the power supply wire is connected in a long distance, the noise of the power supply and the noise radiated to the connecting wire in space can cause certain influence on the key code chip 12 and the driving circuit 11, and the filtering capacitor is added to ensure that the power supply is cleaner; the transmitting dc power supply 17 is used for supplying power to the whole key signal transmitting part, and the transmitting triode 113 is an NPN-type triode.
Preferably, the key signals detected by the key signal transmitting part 1 are transmitted from the metal transmission line connected between the second resistor 112 and the transmitting triode 113 to the key signal receiving part 2, and the plurality of key signals are all transmitted through the metal transmission line, so that the problems of complicated line caused by the transmission of a plurality of transmission lines and easy mutual interference among the plurality of transmission lines are avoided; the transmission signal is a digital signal, so that the signal is more stable in the transmission process.
Preferably, the demodulation circuit 3 includes: a third resistor 21, a fourth resistor 22, a receiving triode 23 and a fourth capacitor 24; the base electrode of the receiving triode 23 is connected with the third resistor 21, the collector electrode is connected with the fourth resistor 22, and the emitter electrode is grounded; the third resistor 21 is connected to the carrier signal output end of the driving circuit; the fourth resistor 22 is connected to the processor 31; one end of the fourth capacitor 24 is connected between the third resistor 21 and the base electrode of the receiving triode 23, and the other end is grounded.
The demodulation circuit 3 is a two-stage inverter and is used as a comparator for carrying out two-stage inversion on a carrier signal, the waveform of coded information (pulse signal) is restored after the two-stage inversion, meanwhile, a low-pass filter is formed by the third resistor 21 and the fourth capacitor 24, a high-frequency carrier wave is filtered, but part of the carrier wave still remains to form noise on the signal wave, at the moment, the carrier noise voltage is about 0.1V, the base stage of the receiving triode 23 only passes through the frequency with the voltage greater than 0.7V, so that the carrier noise is filtered, and the pulse signal with the voltage of 3.3V passes through the base stage of the receiving triode 23; when the driving circuit 3 receives the high level signal from the driving circuit 11, the base voltage of the triode 23 is high level, the collector-emitter of the triode 23 is conducted, and the driving circuit 3 sends out the low level signal. When the driving circuit 3 receives the low level signal from the driving circuit 11, the base voltage of the triode 23 is high level, the collector-emitter of the triode 23 is cut off, and the driving circuit 3 sends out the high level signal. The collector-emitter of the NPN transistor begins to conduct when the base-emitter voltage is greater than the on-voltage (about 0.7V).
One end of the third resistor 21 is connected with the metal transmission line of the key detection part 1, the other end of the third resistor is simultaneously connected with one end of the fourth capacitor 24 and the base electrode of the second triode 23, and the receiving circuit outputs the input pulse signal after carrying out carrier frequency removal processing on the pulse signal;
the positive electrode of the receiving direct current power supply 4 is connected to one end of the fourth resistor 22 for connecting to the processor 31, and the negative electrode is connected to the processor 31 and grounded. The receiving dc power supply 4 supplies power to the key signal receiving section 2, and the negative electrode ground provides a reference for the level signal. The signal transmission is more stable.
Preferably, the transmitting triode 113 and the receiving triode 23 are NPN type transistors. The NPN type triode is suitable for the condition that the power supply voltage is higher than the input signal voltage, and if the power supply voltage is higher than the input signal, the PNP type triode is in a condition of being always conducted, so that the signal cannot be transmitted.
In the application, NPN triode is adopted as the driving circuit, and the condition that the power supply voltage is not matched with the signal level voltage is not needed to be considered.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the description of the present invention and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the invention.
Claims (8)
1. A single-wire transmission key detection circuit, comprising:
a key signal transmitting section comprising:
the key circuit comprises a plurality of keys to be tested which are connected in parallel;
the input port of the key coding chip is connected with the key circuit, codes according to a key signal output by a key to be tested triggered in the key circuit to obtain coding information, and the coding information is output in the form of a digital signal; the key coding chip sends out time-division line scanning signals, and when a key is pressed, the key coding chip reads the corresponding column signal level change so as to judge which key is pressed;
the key circuit comprises at least one branch circuit, and each branch circuit comprises a plurality of keys to be tested which are connected in parallel; each key is connected to at least one row and one column, one end of each branch circuit is connected to one input port of the key coding chip, and the other end of each branch circuit is connected to one coding output port of the key coding chip; the input/code output ports of the key code chips connected with the ports of different branch circuits are not identical; the key coding chip comprises a plurality of coding modes; the port of each coding mode is connected with a group of branch circuits; the ports of each coding mode correspond to the coding output ports of the key coding chip;
the carrier circuit receives the coded information and modulates the coded information onto a high-frequency carrier to form a carrier signal and outputs the carrier signal to the key coding chip;
the driving circuit is connected with the output port of the key coding chip, receives and amplifies the level of the carrier signal when the key to be tested is started and outputs the carrier signal;
a key signal receiving section comprising:
the demodulation circuit is connected with the driving circuit through a metal connecting wire, receives the carrier signal, filters high-frequency carriers in the carrier signal and outputs coding information;
a processor for receiving the encoded information and decoding the encoded information to obtain a key value; and judging whether the key to be tested triggered in the key circuit is qualified or not according to the key value.
2. The single wire transmission key detection circuit of claim 1 wherein said carrier circuit comprises:
the crystal is used for generating a high-frequency carrier wave, and two ends of the crystal are respectively connected to two ports of the key coding chip;
one end of the first capacitor is connected with one end of the crystal, and the other end of the first capacitor is connected with the second capacitor and then connected with the other port of the key code chip;
one end of the second capacitor is connected with the first capacitor, and the other end of the second capacitor is connected with the other end of the crystal;
and one end of the first capacitor connected with the second capacitor is grounded.
3. The single wire transmission key detection circuit of claim 1 wherein said drive circuit comprises:
the base electrode of the emitting triode is connected with the first resistor, the collector electrode of the emitting triode is connected with the second resistor, and the emitting electrode of the emitting triode is grounded; a lead wire is connected between the collector electrode and the second resistor and is used as a carrier signal output end;
the first resistor is connected to the output port of the key coding chip; receiving the carrier signal;
the second resistor is connected to the other output port of the key code chip.
4. The single wire transmission key detection circuit of claim 3, wherein said key signal transmitting section further comprises:
a transmitting direct current power supply, wherein the anode is connected with one end of the second resistor connected with the key code chip, and the cathode is grounded;
and one end of the third capacitor is connected with the positive electrode of the transmitting direct-current power supply, and the other end of the third capacitor is grounded.
5. The single wire transmission key detection circuit of claim 1, wherein said demodulation circuit comprises:
a base electrode of the receiving triode is connected with the third resistor, a collector electrode of the receiving triode is connected with the fourth resistor, and an emitter electrode of the receiving triode is grounded;
the third resistor is connected with the carrier signal output end of the driving circuit;
the fourth resistor is connected to the processor;
and one end of the fourth capacitor is connected between the third resistor and the base electrode of the receiving triode, and the other end of the fourth capacitor is grounded.
6. The single wire transmission key detection circuit of claim 5 wherein said key signal reception further comprises:
and receiving a direct current power supply, wherein one end of the direct current power supply is connected to one end of the fourth resistor, which is used for being connected with the processor, and the other end of the direct current power supply is connected with the processor and is grounded.
7. The single wire transmission key detection circuit of claim 3 wherein said transmitting transistor is an NPN transistor.
8. The single-wire transmission key detection circuit of claim 5, wherein the receiving transistor is an NPN transistor.
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| CN201811346354.6A CN109462405B (en) | 2018-11-13 | 2018-11-13 | Single-wire transmission key detection circuit |
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| CN201811346354.6A CN109462405B (en) | 2018-11-13 | 2018-11-13 | Single-wire transmission key detection circuit |
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| CN111367214A (en) * | 2020-03-20 | 2020-07-03 | 江铃汽车股份有限公司 | Key implementation circuit with diagnosis and protection functions |
| CN112290930A (en) * | 2020-10-22 | 2021-01-29 | 珠海格力电器股份有限公司 | Key detection circuit and household appliance |
| CN113948332B (en) * | 2021-10-29 | 2024-03-22 | 广东美的厨房电器制造有限公司 | Trigger detection circuit, button subassembly and tame electric installation of button |
| CN116028391B (en) * | 2022-07-15 | 2024-03-22 | 荣耀终端有限公司 | Electronic device, peripheral device, and single-wire communication system |
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| CN2745078Y (en) * | 2004-09-28 | 2005-12-07 | 陈力 | Infrared laser remote control pen and receiver thereof |
| CN100530262C (en) * | 2007-05-18 | 2009-08-19 | 天津通广微电子有限公司 | Domestic electric appliance remote controller utilizing laser transmission technique to control remote-control signal |
| CN201111719Y (en) * | 2007-09-25 | 2008-09-10 | 海尔集团公司 | Infrared signal transmission circuit of self-study type report controller |
| CN101814231A (en) * | 2009-02-25 | 2010-08-25 | 鲁永生 | Infrared remote control device for theft-proof alarm of motor vehicle |
| CN101702615A (en) * | 2009-11-09 | 2010-05-05 | 天津理工大学 | Motor infrared remote control rotating speed control system based on double singlechips |
| CN203931175U (en) * | 2014-06-27 | 2014-11-05 | 苏州市群达电子有限公司 | Telepilot detector |
| CN206000283U (en) * | 2016-07-04 | 2017-03-08 | 南昌航空大学 | A kind of infrared remote control password short message alarm lock |
| CN106781423A (en) * | 2016-12-28 | 2017-05-31 | 郑州欧印数字科技有限公司 | A kind of anti-interference multichannel IR remote controller circuit |
| CN206788225U (en) * | 2017-02-21 | 2017-12-22 | 国网甘肃省电力公司金昌供电公司 | A kind of anti-remote control electricity filching device of the intelligence with self-learning function |
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