TWM584574U - Communication device and receiving and transmitting units thereof - Google Patents

Abstract

This case provides a communication device, and a receiving unit and a sending unit thereof. The communication device includes a receiving unit and a sending unit. The receiving unit generates a step-down communication command according to a first communication command from another communication device, and generates a pulse width modulation signal according to the step-down communication command, and decodes the pulse width modulation signal to generate a decoded signal. The transmitting unit includes an operational amplifier and a switching circuit. The operational amplifier generates a pilot signal based on a voltage signal. The operational amplifier includes a positive input terminal, a negative input terminal, and an output terminal coupled to the negative input terminal. The switching circuit is coupled between the negative input terminal and the output terminal of the operational amplifier. The switching circuit is turned on according to the conduction signal and generates a current signal as a second communication command to be output to another communication device according to the voltage signal during the conduction.

Description

Communication device and its receiving unit and sending unit

This case relates to a communication device, and particularly to a communication device suitable for a fire protection system.

Traditionally, communication devices often use capacitors to convert voltages to decode communication commands received by the communication devices. However, the use of capacitors to convert voltages tends to cause unstable voltage after conversion, resulting in decoding errors and communication failures. Moreover, the communication device usually only has the function of transmitting and receiving signals without other functions. The function of the communication device is single and it is difficult to support different product applications. Further, traditional communication devices often use many components, which results in complicated components. When a communication device fails, it is difficult for maintenance personnel to detect the cause of the failure.

This case provides a communication device including a receiving unit and a sending unit. The receiving unit is used for receiving a first communication command from another communication device and generating a first communication command after voltage reduction, and generating a pulse width modulation signal according to the first communication command after voltage reduction, and The pulse width modulation signal at the high level and the pulse width at the low level are decoded to generate a decoded signal. The transmitting unit includes an operational amplifier and a switching circuit. The operational amplifier is used to generate a pilot signal based on the voltage signal. The operational amplifier includes a positive input terminal, a negative input terminal, and an output terminal coupled to the negative input terminal. The positive input terminal receives the aforementioned voltage signal, and the output terminal outputs the aforementioned pilot signal. The switching circuit is coupled between the negative input terminal and the output terminal of the operational amplifier. The switching circuit is turned on according to the conduction signal and generates a current signal as a second communication command to be output to another communication device according to the voltage signal during the conduction.

This case provides a receiving unit, which includes a voltage divider circuit, a digital analog converter, a comparison circuit, and a calculation circuit. The voltage dividing circuit is used for receiving communication instructions from a communication device, and performing voltage division conversion on the communication instructions to generate a communication instruction after voltage reduction. The digital analog converter is used for generating a reference voltage according to a digital signal. The comparison circuit is used to compare the reference voltage and the communication command after the voltage reduction to generate a pulse width modulation signal. The calculation circuit is used to calculate the pulse width of the pulse width modulation signal at a high level and the pulse width of the pulse width modulation signal at a low level to generate a decoded signal.

The present invention provides a transmitting unit including a digital analog converter, an operational amplifier, and a switching circuit. The digital analog converter is used for generating a voltage signal according to a digital signal. The operational amplifier is used to generate a pilot signal based on the voltage signal. The operational amplifier includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal receives the aforementioned voltage signal, the output terminal is coupled to the negative input terminal, and the output terminal outputs the aforementioned conduction signal. The switch circuit is coupled between the negative input terminal and the output terminal to form a negative feedback line. The switch circuit is turned on according to the conductive signal and generates a current signal as a communication command to be output to the communication device according to the voltage signal when the switch circuit is turned on.

FIG. 1 is a schematic block diagram of an embodiment of a communication device 1 according to this case. Please refer to FIG. 1. The communication device 1 can communicate bidirectionally with another communication device 2. The communication device 1 can receive the communication instruction S1 from the communication device 2 (for convenience of description, hereinafter referred to as the first communication instruction S1) and decode the first communication instruction S1 (hereinafter referred to as the instruction receiving program), and the communication device 1 can generate another A communication instruction (hereinafter referred to as a second communication instruction S2) is sent to the communication device 2 (hereinafter referred to as a command sending program) to establish a two-way communication between the communication device 1 and the communication device 2. In one embodiment, the first communication instruction S1 is a voltage modulation signal.

Take the communication device 1 including a set of a receiving unit 11 and a sending unit 12 as an example. As shown in FIG. 1, the communication device 1 includes a receiving unit 11, a sending unit 12, and an input / output line 13. In the instruction receiving program, the input / output line 13 receives the first communication instruction S1 from the communication device 2. The input / output line 13 transmits the first communication instruction S1 to the receiving unit 11, and the receiving unit 11 performs a step-down process on the first communication instruction S1. In order to generate the first communication command S1 after step-down, the receiving unit 11 then generates a pulse width modulation (PWM) signal S3 according to the first step-down communication command S1. The receiving unit 11 calculates the PWM signal S3 in The high-level pulse width (hereinafter referred to as the first width) and the pulse width of the PWM signal S3 at the low level (hereinafter referred to as the second width). The receiving unit 11 then decodes the PWM signal S3 according to the first width and the second width to generate the A decoded signal S4. For example, a logic "1" is represented by a pulse width at the high bit being twice the pulse width at the low bit, and a logic "0" is represented by a pulse width at the low bit being twice the pulse width at the high bit For example, when the receiving unit 11 calculates that the first width is twice the second width, the receiving unit 11 generates a decoding signal S4 containing a logic "1". When the receiving unit 11 calculates the second width as two of the first width, When the frequency is doubled, the receiving unit 11 generates a decoding signal S4 containing a logic "0".

On the other hand, in the instruction sending program, the sending unit 12 generates a second communication instruction S2 and sends the second communication instruction S2 to the communication device 2. The transmitting unit 12 includes an operational amplifier 121 and a switching circuit 122. The operational amplifier 121 includes a positive input terminal 1211, a negative input terminal 1212, and an output terminal 1213. The positive input terminal 1211 receives a voltage signal V1, and the voltage signal V1 includes different voltage levels switched between a high level and a low level; the negative input terminal 1212 is coupled to the output terminal 1213 via the switch circuit 122 (that is, the switch circuit 122 is coupled to the negative Between the input terminal 1212 and the output terminal 1213), the operational amplifier 121 has a negative feed-back circuit.

Here, the operational amplifier 121 generates the conduction signal S5 when the voltage signal V1 received at the positive input terminal 1211 is at a high level, and the switch circuit 122 receives the conduction signal S5 and conducts the conduction signal S5 according to the conduction signal; and, according to the negative feedback line of the operational amplifier 121, The negative input terminal 1212 of the operational amplifier 121 generates the voltage level of the voltage signal V1 according to the voltage signal received by the positive input terminal 1211. The switch circuit 122 receives the voltage level of the voltage signal V1 generated by the negative input terminal 1212. When conducting, a current signal is generated according to the voltage level of the voltage signal V1. The current signal is used as the second communication instruction S2 and the second communication instruction S2 is output to the communication device 2 through the input / output line 13 of the communication device 1. Based on this, the switch circuit 122 generates a current signal based on the voltage signal with a stable and accurate voltage level from the operational amplifier 121, and the current signal generated by the switch circuit 122 is also relatively stable and accurate, thereby improving the communication device 1 and the communication device 2 Communication quality.

In an embodiment, as shown in FIG. 1, the transmitting unit 12 further includes a load 127 coupled between the switching circuit 122 and the ground. The load 127 may be a resistor having a fixed resistance value. The switching circuit 122 is based on a voltage signal. The voltage level of V1 and the load 127 generate the second communication command S2 as a constant current signal. The current of the constant current signal is relatively stable, thereby improving the communication quality between the communication device 1 and the communication device 2.

Furthermore, as shown in FIG. 1, the receiving unit 11 includes a voltage dividing circuit 111, a digital-to-analog converter 112 (hereinafter referred to as a first digital-to-analog converter 112), a comparison circuit 113, and a calculation circuit 114. The voltage dividing circuit 111 is coupled between the input / output line 13 and the comparison circuit 113. The comparison circuit 113 is coupled between the voltage dividing circuit 111 and the calculation circuit 114, and the comparison circuit 113 is coupled between the first digital analog converter 112 and the calculation circuit 114. In one embodiment, the first communication instruction S1 has a voltage level of 30-40 V. The voltage dividing circuit 111 receives the first communication instruction S1 from the input / output line 13 and performs voltage division conversion on the first communication instruction S1. The first communication command S1 after voltage reduction is generated, and the first communication command S1 after voltage reduction may have a voltage level of 6 V or 3.3 V. The first digital analog converter 112 generates a reference voltage V2 according to a digital signal (hereinafter referred to as a first digital signal D1). The two input terminals of the comparison circuit 113 are respectively coupled to the output terminals of the voltage divider circuit 111 and the first digital analog converter 112. The comparison circuit 113 receives the step-down first communication instruction S1 from the voltage divider circuit 111 and from the first digital The analog converter 112 receives the reference voltage V2, and the comparison circuit 113 compares the reference voltage V2 with the first communication command S1 after the voltage step-down. When the voltage level of the first communication command S1 after the voltage step-down is greater than the reference voltage V2, the comparison circuit 113 Output high level. When the voltage level of the first communication instruction S1 after the voltage step-down is lower than the reference voltage V2, the comparison circuit 113 outputs a low level. Therefore, the comparison circuit 113 is based on the first communication command S1 and the reference voltage V2 after the voltage step-down. The PWM signal S3 is generated. The calculation circuit 114 receives the PWM signal S3 from the comparison circuit 113. The calculation circuit 114 calculates a first width and a second width of the PWM signal S3 to decode the PWM signal S3 and generate a decoded signal S4.

In one embodiment, the first communication instruction S1 is a multi-segment voltage signal. The receiving unit 11 may include a complex first digital analog converter 112, a complex comparison circuit 113, and a complex calculation circuit 114. The complex first digital analog converter 112 generates different reference voltages V2, and the complex comparison circuit 113 respectively at different time points. The first communication instruction S1 after the voltage step-down is compared with a different reference voltage V2, so that the complex calculation circuit 114 generates a plurality of decoded signals S4 corresponding to the first communication instruction S1 of a plurality of voltage signals.

In an embodiment, please refer to FIG. 1 and FIG. 2 together. The voltage dividing circuit 111 includes two resistors R1 and R2 (hereinafter referred to as a first resistor R1 and a second resistor R2) connected in series with each other. The first resistor R1 is coupled to the communication. The input / output line 13 of the device 1 and the second resistor R2, the second resistor R2 is coupled to the first resistor R1 and the ground terminal, and the resistance value of the second resistor R2 is greater than the resistance value of the first resistor R1. Therefore, according to the resistance values of the first resistor R1 and the second resistor R2, the voltage dividing circuit 111 performs a voltage division conversion on the first communication instruction S1 to generate a first communication instruction S1 after step-down, and one of the comparison circuits 113 The input terminal is coupled to the connection point C between the first resistor R1 and the second resistor R2, and the comparison circuit 113 generates a PWM signal S3 according to the first communication command S1 and the reference voltage V2 after the voltage reduction received from the connection point C.

In an embodiment, please refer to FIG. 1 and FIG. 2 together. The sending unit 12 includes a digital analog converter 123 (hereinafter referred to as a second digital analog converter 123). The output end of the second digital analog converter 123 is coupled to the operation. The positive input terminal 1211 of the amplifier 121, the second digital analog converter 123 generates a voltage signal V1 according to a digital signal (hereinafter referred to as the second digital signal D2), and the second digital analog converter 123 sends the voltage signal V1 to the operational amplifier 121. The positive input terminal 1211 causes the operational amplifier 121 to generate the conduction signal S5, and the negative input terminal 1212 of the operational amplifier 121 generates the voltage level of the voltage signal V1.

Furthermore, as shown in FIG. 2, the switching circuit 122 includes a transistor, such as a metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The switching circuit 122 includes a gate terminal G and a source terminal. S and drain extreme D. The gate terminal G is coupled to the output terminal 1213 of the operational amplifier 121, the source terminal S is coupled to the first resistor R1 and the input / output circuit 13 of the voltage dividing circuit 111, and the drain terminal D is coupled to the negative input terminal 1212 and the load 127 of the operational amplifier 121. The gate terminal G is coupled to the output terminal 1213 of the operational amplifier 121. Based on this, when the operational amplifier 121 outputs the conductive signal S5 according to the voltage signal V1 at a high level, the gate terminal G receives the conductive signal S5 from the output terminal 1213 of the operational amplifier 121 to turn on the switching circuit 122. When the switching circuit 122 turns on, The voltage level of the voltage signal V1 generated by the negative input terminal 1212 of the operational amplifier 121 generates a current signal as the second communication instruction S2. On the other hand, when the voltage signal V1 is at a low level, the operational amplifier 121 outputs a low level and does not output a conducting signal S5. At this time, the gate terminal G receives the low level, and the drain terminal D according to the load 127 has a low level. At this time, the switching circuit 122 is cut-off, and the switching circuit 122 stops generating a current signal. Based on this, according to the high level and the low level of the voltage signal V1, the switch circuit 122 generates a corresponding current modulation signal to generate different commands to communicate with the communication device 2.

In an embodiment, as shown in FIG. 1, the communication device 1 further includes a controller 15. The controller 15 may be a microcontroller (MCU). The controller 15 is coupled to the calculation circuit 114 and the second digital analog converter 123. The controller 15 receives the decoded signal S4 from the calculation circuit 114. The controller 15 generates a corresponding second digital signal D2 according to different decoded signals S4, so that the first The digital-to-analog converter 123 performs digital-to-analog conversion according to a different second digital signal D2 to generate a corresponding voltage signal V1, and the switching circuit 122 generates a current signal corresponding to the voltage signal V1. Here, according to the different first communication instruction S1, the sending unit 12 may generate a corresponding second communication instruction S2 in response to the first communication instruction S1 sent by the communication device 2.

In other embodiments, the controller 15 may generate a different second digital signal D2 by default or according to the design of the designer of the communication device 1, so that the second digital analog converter 123 performs corresponding digital analog conversion to generate a corresponding digital signal. The voltage signal V1 causes the switch circuit 122 to generate different current signals correspondingly. Based on this, the communication device 1 can generate corresponding second communication instructions S2 according to different communication protocols of the communication devices 2 of different models / specifications, and the communication device 1 has better compatibility.

In an embodiment, the communication device 1 has a first operation mode and a second operation mode. When the communication device 1 is in the first operation mode, the sending unit 12 generates and sends a second communication instruction S2. When the communication device 1 is in the first operation mode, In the two operation modes, the sending unit 12 supports a voltage detection function. The sending unit 12 does not generate and does not send the second communication instruction S2. In the second operation mode, the sending unit 12 receives the first communication command S1 after the voltage reduction, and detects the voltage level of the first communication command S1 after the voltage reduction. In detail, please refer to FIG. 2 and FIG. 3 together. The sending unit 12 further includes two multiplexers 124 and 125 (hereinafter referred to as a first multiplexer 124 and a second multiplexer 125 respectively) and a switch 126. The first multiplexer 124 and the second multiplexer 125 are two-to-one multiplexers (2-to-1 mux). The two input terminals of the first multiplexer 124 are respectively coupled to the second digital analog converter 123 and the connection point C. The output terminal of the first multiplexer 124 is coupled to the positive input terminal 1211 of the operational amplifier 121. The two input terminals of the second multiplexer 125 are respectively coupled to the output terminal 1213 and the drain terminal D of the operational amplifier 121, and the output terminal of the second multiplexer 125 is coupled to the negative input terminal 1212 of the operational amplifier 121. The switch 126 is coupled between the gate terminal G and the output terminal 1213 of the operational amplifier 121.

The first multiplexer 124, the second multiplexer 125 and the switch 126 are controlled by the controller 15. When the communication device 1 is in the first operation mode, as shown in FIG. 2, the controller 15 generates a control signal C1 to control the output of the first multiplexer 124 to be coupled to the second digital analog converter 123, and the controller 15 generates a control The signal C2 controls the output terminal of the second multiplexer 125 to be coupled to the drain terminal D, and the controller 15 generates a control signal C3 to control the switch 126 to be turned on. Here, the output terminal 1213 of the operational amplifier 121 is coupled to the negative input terminal 1212 via the switch 126, the switch circuit 122, and the second multiplexer 125 to form the aforementioned negative feedback line, and the positive input terminal 1211 of the operational amplifier 121 is connected via the first A multiplexer 124 is coupled to the second digital analog converter 123. The operational amplifier 121 generates a current signal based on the voltage signal V1 and the aforementioned negative feedback line control switch circuit 122.

On the other hand, when the communication device 1 is in the second operation mode, as shown in FIGS. 3 and 4, the controller 15 generates a control signal C1 to control the output end of the first multiplexer 124 to be coupled to the connection point C, and the controller 15 A control signal C3 is generated to control the switch 126 to be turned off, and a control signal C2 is generated to control the output terminal of the second multiplexer 125 to be coupled to the output terminal 1213 of the operational amplifier 121. Here, the line between the output terminal 1213 of the operational amplifier 121 and the gate terminal G is open, and the output terminal 1213 of the operational amplifier 121 is coupled to the negative input terminal 1212 via the second multiplexer 125 to form a single gain ( uni-gain), and the positive input terminal 1211 of the operational amplifier 121 is coupled to the voltage divider circuit 111. The positive input terminal 1211 of the operational amplifier 121 receives the step-down first communication instruction S1 from the connection point C via the first multiplexer 124, and based on the aforementioned single-gain feedback line, the output terminal 1213 of the operational amplifier 121 outputs a step-down. After the voltage level of the first communication instruction S1, the output terminal 1213 of the operational amplifier 121 may be further coupled to the analog-to-digital converter 128 to convert the voltage level of the step-down first communication instruction S1 into a digital signal. As other applications.

In an embodiment, please refer to FIG. 5. The communication devices 1 and 2 are used in a fire protection system. The communication device 1 may be a smoke detection device or a manual alarm device, and the communication device 2 may be a fire engine. The communication device 2 which is a fire engine can be coupled to at least one communication device 1 (FIG. 4 is based on the communication device 2 being coupled to three communication devices 1 as an example, but this case is not limited to this case). The communication device 2 is coupled to the communication device 1 via a power line 3 and a ground line 4. The communication device 2 sends a power signal to the communication device 1 via the power line 3, and the communication device 2 sends the aforementioned first communication instruction S1 to the communication device 1 via the power line 3 to communicate with the communication device 1. In addition, the communication device 1 also sends a second communication instruction S2 to the communication device 2 via the power line 3 to communicate with the communication device 2. When the communication device 2 detects that the current value on the power line 3 changes, the communication device 2 can know that the communication device 1 sends a second communication instruction S2. For example, when the communication device 1 does not send the second communication instruction S2, the current value on the power line 3 is 2 mA. When the communication device 1 sends the second communication instruction S2 with 50 mA, the current value on the power line 3 is 2 mA. The current value changes to 52 mA. At this time, the communication device 2 further decodes the second communication instruction S2 to complete the communication between the communication device 1 and the communication device 2.

To sum up, according to an embodiment of the communication device, the receiving unit, and the transmitting unit of the present case, the communication device supports the function of voltage detection, and the transmitting unit of the communication device generates a constant current signal as a communication command, a constant current signal Can improve communication quality. In addition, the sending unit and the receiving unit include digital analog converters. The digital analog converters generate adjustable voltage signals according to the adjustable digital signals. In this way, the transmitting units and receiving units can be flexibly designed and transmitted according to the communication specifications of different fire protection hosts. The unit and receiving unit can operate flexibly, thereby improving the performance and compatibility of the product.

Although this case has been disclosed with examples as above, it is not intended to limit this case. Any person with ordinary knowledge in the technical field can make some changes and retouching without departing from the spirit and scope of this case. Therefore, the scope of protection of this case Subject to the scope of the attached patent application.

1‧‧‧ communication device
11‧‧‧Receiving unit
111‧‧‧Voltage Dividing Circuit
C‧‧‧ connection point
R1‧‧‧first resistor
R2‧‧‧Second resistor
112‧‧‧The first digital analog converter
113‧‧‧Comparison circuit
114‧‧‧Calculation Circuit
12‧‧‧ sending unit
121‧‧‧ Operational Amplifier
1211‧‧‧ Positive input
1212‧‧‧ Negative input
1213‧‧‧ output
122‧‧‧Switch circuit
G‧‧‧ Gate extreme
D‧‧‧Extreme
S‧‧‧Source Extreme
123‧‧‧Second Digital Analog Converter
124‧‧‧The first multiplexer
125‧‧‧Second Multiplexer
126‧‧‧Switch
127‧‧‧Load
128‧‧‧ Analog Digital Converter
13‧‧‧I / O line
15‧‧‧controller
2‧‧‧ communication device
3‧‧‧ power line
4‧‧‧ ground line
C‧‧‧ connection point
C1‧‧‧Control signal
C2‧‧‧Control signal
C3‧‧‧Control signal
D1‧‧‧ first digital signal
D2‧‧‧Second digital signal
V1‧‧‧Voltage signal
V2‧‧‧Reference voltage
S1‧‧‧First communication instruction
S2‧‧‧Second communication instruction
S3‧‧‧PWM signal
S4‧‧‧ decoded signal
S5‧‧‧ pilot signal

[Figure 1] A block diagram of an embodiment of a communication device according to the present case.
[FIG. 2] A circuit diagram of one embodiment of the two communication devices of FIG.
[Fig. 3] Schematic diagram of signal flow when the communication device of Fig. 1 operates in the second operation mode.
[Fig. 4] A schematic block diagram of an embodiment of a transmitting unit of the communication device of Fig. 1. [Fig.
[FIG. 5] It is a schematic diagram of an embodiment in which the two communication devices of FIG. 1 are applied to a fire protection system.

Claims (11)

A communication device suitable for a fire protection system includes:
A receiving unit for receiving a first communication command from another communication device and generating the first communication command after voltage reduction; and generating a pulse width modulation signal according to the first communication command after voltage reduction, and Decoding the pulse width modulation signal based on the pulse width modulation signal at a high level and the pulse width at a low level to generate a decoded signal; and a transmitting unit including:
An operational amplifier for generating a lead communication signal based on a voltage signal, including:
A positive input terminal for receiving the voltage signal;
A negative input terminal; and an output terminal coupled to the negative input terminal to output the conduction signal; and a switching circuit coupled between the negative input terminal and the output terminal to conduct conduction according to the conduction signal In addition, a current signal is generated as a second communication command and output to the other communication device according to the voltage signal during the conduction. The communication device according to claim 1, wherein the receiving unit includes:
A voltage dividing circuit that performs voltage division conversion on the first communication instruction to generate the first communication instruction after voltage reduction;
A first digital analog converter, generating a reference voltage according to a first digital signal;
A comparison circuit that compares the reference voltage with the first communication instruction after voltage reduction to generate the pulse width modulation signal; and a calculation circuit that calculates the pulse width modulation signal at a high level and the pulse width modulation The signal is pulsed at a low level to generate the decoded signal. The communication device according to claim 2, wherein the voltage dividing circuit includes a first resistor and a second resistor connected to each other, and a voltage drop occurs at a connection point between the first resistor and the second resistor. The first communication instruction. The communication device according to claim 2, wherein the transmitting unit further comprises a second digital analog converter coupled to the positive input terminal, and the second digital analog converter generates the voltage signal according to a second digital signal. The communication device according to claim 4, wherein the positive input terminal of the operational amplifier further receives the first communication instruction after voltage reduction, and the operational amplifier generates a voltage level according to the first communication instruction after voltage reduction. And the output terminal outputs the voltage level. The communication device according to claim 5, wherein the sending unit further includes a switch, a first multiplexer, and a second multiplexer. The communication device has a first operation mode and a second operation mode. When the communication device is in the first operation mode, the switch is turned on and is coupled to a control terminal and the output terminal of the switch circuit, and the first multiplexer is coupled to the second digital analog conversion circuit and the positive input terminal. And the second multiplexer is coupled to a drain terminal of the switching circuit and the negative input terminal, the operational amplifier generates the conduction signal according to the voltage signal in the first operation mode; when the communication device is in the first In the two operation modes, the switch is turned off, which causes an open circuit between the control terminal and the output terminal, and the first multiplexer is coupled to the positive input terminal and the voltage dividing circuit, and the second multiplexer is coupled. Connected to the negative input terminal and the output terminal, the operational amplifier generates and outputs the voltage level in the second operation mode according to the first communication instruction after step-down. The communication device according to claim 1, further comprising:
A controller coupled to the receiving unit and the sending unit, and the controller generates a corresponding second digital signal according to the decoded signal;
The transmitting unit further includes a second digital analog converter coupled to the positive input terminal. The second digital analog converter generates the voltage signal according to the second digital signal. The communication device according to claim 1, wherein the first communication instruction is a voltage modulation signal, and the input terminal further receives a power signal through a power line, and the power line is coupled to the communication device and the other communication Device, and the first communication instruction is from the power line. The communication device according to claim 1, wherein the transmitting unit further comprises a load having a resistance value coupled between the switch circuit and the ground terminal, and the switch circuit is generated according to the voltage level of the voltage signal and the load. This current signal is a constant current. A receiving unit, which communicates with a communication device, includes:
A voltage dividing circuit for receiving a communication instruction from a communication device, and performing voltage division conversion on the communication instruction to generate the communication instruction after voltage reduction;
A digital analog converter for generating a reference voltage according to a digital signal;
A comparison circuit for comparing the reference voltage with the communication command after voltage reduction to generate a pulse width modulation signal; and a calculation circuit for calculating the pulse width of the pulse width modulation signal at a high level and the pulse The width-modulates the pulse width of the signal at a low level to generate a decoded signal. A sending unit, which communicates with a communication device, includes:
A digital analog converter for generating a voltage signal according to a digital signal;
An operational amplifier for generating a lead communication signal based on the voltage signal, including:
A positive input terminal for receiving the voltage signal;
A negative input terminal; and an output terminal coupled to the negative input terminal for outputting the conduction signal; and a switch circuit coupled between the negative input terminal and the output terminal to form a negative feedback line, It is used for conducting according to the conducting signal and generating a current signal according to the voltage signal when the conducting signal is output to the communication device as a communication command.