Display control link protection circuit of fire alarm system
By using ferrite beads and isolated transceivers in the fire alarm system to enhance electromagnetic compatibility, the failure problem of the display unit in strong electromagnetic radiation and electrostatic discharge environments was solved, achieving higher EMC reliability.
Patent Information
- Application Number
- CN202511411538.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2025-12-12
AI Technical Summary
The display unit of a fire alarm system is prone to electromagnetic compatibility issues in special industrial environments with strong electromagnetic radiation or frequent electrostatic discharge, leading to screen malfunction and failure of human-machine interaction functions.
Ferrite beads are connected in series on the data bus and control signal link between the microcontroller and the TFT display screen, and an isolated transceiver is used in the communication interface with the host computer to enhance electromagnetic compatibility.
It significantly improves the electromagnetic compatibility of the display unit, effectively suppresses high-frequency noise interference and electrostatic discharge, and enhances the reliability of the system in EMC testing.
Smart Images
Figure CN121121932A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fire alarm circuit technology, specifically to a display and control link protection circuit for a fire alarm system. Background Technology
[0002] In special industrial environments with strong electromagnetic radiation or frequent electrostatic discharge, the display units of fire alarm systems are prone to serious malfunctions due to electromagnetic compatibility (EMC) issues. This manifests as screen flickering, blackouts, garbled display characters, or touchscreen failure, leading to the inability of human-machine interaction and severely impacting the monitoring and operational efficiency of the fire alarm system. Summary of the Invention
[0003] To address the aforementioned technical problems, this invention provides a display and control link protection circuit for a fire alarm system, which can significantly enhance the electromagnetic compatibility of the display unit.
[0004] The technical solution is as follows: a display and control link protection circuit for a fire alarm system, comprising a system control circuit, a power supply circuit, a communication circuit, and a TFT screen driving interface circuit. The control circuit includes a microcontroller U1. The communication circuit includes an isolated transceiver U11 of model TDA51S485HC. The TFT screen driving interface circuit includes a TFT screen driving circuit and a TFT screen interface circuit. The TFT screen interface circuit includes a TFT screen interface J6. A ferrite bead is connected in series on the data bus and control signal link between the TFT screen interface J6 and the microcontroller U1.
[0005] A further feature is that the microcontroller U1 is an STM32H743ZI, and the microcontroller U1 is connected to memory chips U7 and U6. The microcontroller U1 is also connected to a system detection circuit, which includes transistors Q101 and Q102. The base of transistor Q101 is connected to one end of resistor R208 and the collector of transistor Q102. The collector of transistor Q101 is connected to one end of resistor R207, one end of capacitor C11, and pin 43 of the microcontroller U1. The other ends of resistor R207 and resistor R208 are connected to VDD3.3V. The base of transistor Q102 is connected to one end of resistor R209 and one end of resistor R210. The other end of resistor R210 is connected to one end of capacitor C153 and the anode of Zener diode ZD1. The cathode of Zener diode ZD1 is connected to the power supply input DC+. The other ends of capacitor C153, resistor R209, the emitter of transistor Q102, the emitter of transistor Q101, and the other end of capacitor C11 are all grounded. The power supply circuit includes a voltage regulator U3 that converts the power input DC+ to VCC and a voltage regulator U5 that converts VCC to VDD 3.3V. In the communication circuit, pin 1 of the isolated transceiver U11 is connected to one end of capacitor C138, one end of capacitor E109, and VDD 3.3V. Pin 2 of the isolated transceiver U11 is connected to the other ends of capacitor C138 and capacitor C139 and ground. Pin 3 of the isolated transceiver U11 is connected to pin 76 of the microcontroller U1. Pins 4 and 5 of the isolated transceiver U11 are connected and connected to one end of resistor R311 and pin 81 of the microcontroller U1. The other end of resistor R311 is connected to VDD 3.3V. Pin 6 of the isolated transceiver U11 is connected to pin 75 of the microcontroller U1. Pin 12 of the isolated transceiver U11 is connected to one end of resistor R608. Pin 13 of the isolated transceiver U11 is connected to... One end of resistor R607 is connected to one end of resistor R107, the anode of Zener diode T202, and one end of fuse F102. The other end of resistor R107 outputs VCC3. The other end of resistor R607 is connected to one end of resistor R106, one end of fuse F101, and the cathode of Zener diode T202. Pin 15 of isolated transceiver U11 is connected to one end of capacitor C139, one end of capacitor E110, and the other end of resistor R106. The other ends of capacitor C139 and capacitor E110 are connected to pin 16 of isolated transceiver U11 and output VCC3. The other ends of fuse F101 and fuse F102 are connected to host computer interface J5 through common mode inductor L5. The TFT screen driving circuit includes an LED driver U2 and a boost converter U3. Pin 5 of the LED driver U2 is connected to one end of inductor L3, one end of capacitor E107, and VCC. The other end of capacitor E107 is grounded. Pin 4 of the LED driver U2 is connected to one end of resistor R309 and one end of resistor R803. The other end of resistor R309 is connected to pin 7 of the microcontroller U1. The other end of resistor R803 is grounded. Pin 1 of the LED driver U2 is connected to the anode of diode D201 and the other end of inductor L3. The cathode of diode D201 is connected to capacitor C501. One end of the capacitor C501 is connected to pins 1 and 2 of the TFT screen interface J6. The other end of the capacitor C501 is connected to pin 2 of the LED driver U2 and ground. Pin 3 of the LED driver U2 is connected to one end of resistor R116. The other end of resistor R116 is connected to one end of resistor R10 and pins 3 and 4 of the TFT screen interface J6. Pin 5 of the boost converter U3 is connected to one end of inductor L5, one end of resistor R310, one end of capacitor C143, one end of capacitor E108, and VCC. Pin 4 of the boost converter U3 is connected to the other end of resistor R310. The other end of capacitor C143 and capacitor E108 are connected to... The other end of 108 is grounded. Pin 2 of the boost converter U3 is grounded, and pin 3 is connected to one end of resistor R702. The other end of resistor R702 is connected to one end of resistor R701, one end of capacitor C144, and one end of resistor R5. Pin 1 of the boost converter U3 is connected to the anode of diode D202, one end of capacitor C141, one end of capacitor C142, and the other end of inductor L5. The other end of capacitor C141 is connected to pin 3 of Schottky diode D501. Pin 2 of Schottky diode D501 is connected to one end of resistor R3 and one end of capacitor C145. The other end of resistor R3 is connected to resistor R90. One end of the capacitor is connected to the cathode of Zener diode V1, one end of capacitor C601, one end of capacitor C502, one end of capacitor C147, and pin 41 of the TFT screen interface J6. The other end of the resistor R901, the anode of Zener diode V1, the other end of capacitor C601, the other end of capacitor C502, and the other end of capacitor C147 are all grounded. The other end of capacitor C145 is connected to pin 1 of Schottky diode D501, the cathode of diode D202, one end of resistor R701, one end of capacitor C144, one end of capacitor C504, one end of capacitor C603, and pin 43 of the TFT screen interface J6. The other ends of resistor R5, capacitor C504, and capacitor C603 are all grounded. The other end of capacitor C142 is connected to pin 3 of Schottky diode D502. Pin 1 of Schottky diode D502 is connected to one end of capacitor C146 and one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R902, the anode of Zener diode V2, one end of capacitor C602, one end of capacitor C503, one end of capacitor C148, and pin 42 of TFT screen interface J6.Pin 2 of the Schottky diode D502 is connected to the other end of capacitor C146, the other end of resistor R902, the cathode of Zener diode V2, the other end of capacitor C602, the other end of capacitor C503, and the other end of capacitor C148, all of which are grounded. Pin 32 of the TFT screen interface J6 is connected to pin 46 of the microcontroller U1 via ferrite bead B101; pin 31 of the TFT screen interface J6 is connected to pin 41 of the microcontroller U1 via ferrite bead B102; pin 30 of the TFT screen interface J6 is connected to pin 26 of the microcontroller U1 via ferrite bead B103; pin 29 of the TFT screen interface J6 is connected to pin 100 of the microcontroller U1 via ferrite bead B104; and pin 28 of the TFT screen interface J6 is connected to pin 68 of the microcontroller U1 via ferrite bead B105. Pin 25 of the TFT screen interface J6 is connected to pin 42 of the microcontroller U1 via ferrite bead B106; pin 24 of the TFT screen interface J6 is connected to pin 64 of the microcontroller U1 via ferrite bead B107; pin 23 of the TFT screen interface J6 is connected to pin 69 of the microcontroller U1 via ferrite bead B108; pin 22 of the TFT screen interface J6 is connected to pin 70 of the microcontroller U1 via ferrite bead B109; and pin 21 of the TFT screen interface J6 is connected to pin 97 of the microcontroller U1 via ferrite bead B110. Pin 20 of the TFT screen interface J6 is connected to pin 93 of the microcontroller U1 via ferrite bead B111; pin 16 of the TFT screen interface J6 is connected to pin 126 of the microcontroller U1 via ferrite bead B112; pin 15 of the TFT screen interface J6 is connected to pin 65 of the microcontroller U1 via ferrite bead B113; pin 14 of the TFT screen interface J6 is connected to pin 37 of the microcontroller U1 via ferrite bead B114; and pin 13 of the TFT screen interface J6 is connected to pin 139 of the microcontroller U1 via ferrite bead B115. Pin 12 of the TFT screen interface J6 is connected to pin 140 of the microcontroller U1 via ferrite bead B116; pin 9 of the TFT screen interface J6 is connected to pin 66 of the microcontroller U1 via ferrite bead B117; pin 10 of the TFT screen interface J6 is connected to pin 40 of the microcontroller U1 via ferrite bead B118; pin 11 of the TFT screen interface J6 is connected to pin 96 of the microcontroller U1 via ferrite bead B119; and pin 37 of the TFT screen interface J6 is connected to pin 67 of the microcontroller U1 via ferrite bead B120.
[0006] By employing this invention, ferrite beads are connected in series on the data bus and control signal link between the microcontroller and the TFT display screen. Simultaneously, isolation technology (isolated transceiver) is used in the communication interface with the host computer, which can significantly enhance the electromagnetic compatibility (EMC) performance of the display unit. This design can effectively suppress high-frequency noise interference, block common-mode interference paths, and has strong resistance to harsh electromagnetic environments such as electrostatic discharge (ESD), electromagnetic radiation, and conducted interference, thereby significantly improving the reliability of the system in EMC testing. Attached Figure Description
[0007] Figure 1 This is a schematic diagram of the control circuit of the system of the present invention; Figure 2 This is a schematic diagram of the power supply circuit of the present invention; Figure 3 This is a schematic diagram of a communication circuit. Figure 4 This is a schematic diagram of the TFT screen driving circuit. Figure 5 This is a schematic diagram of the interface circuit for a TFT screen. Detailed Implementation
[0008] See Figures 1 to 5 As shown, a display and control link protection circuit for a fire alarm system includes a system control circuit, a power supply circuit, a communication circuit, and a TFT screen driving interface circuit. The control circuit includes a microcontroller U1, model STM32H743ZI, which is connected to memory chips U7 and U6. Microcontroller U1 is also connected to a system detection circuit, which includes transistors Q101 and Q102. The base of transistor Q101 is connected to one end of resistor R208 and the collector of transistor Q102. The collector of transistor Q101 is connected to one end of resistor R207, one end of capacitor C11, and pin 43 of microcontroller U1. The other end of resistor R207 is connected to... The other end of resistor R208 is connected to VDD3.3V. The base of transistor Q102 is connected to one end of resistor R209 and one end of resistor R210. The other end of resistor R210 is connected to one end of capacitor C153 and the anode of Zener diode ZD1. The cathode of Zener diode ZD1 is connected to the power supply input DC+. The other ends of capacitor C153, resistor R209, emitters of transistors Q102 and Q101, and the other end of capacitor C11 are all grounded. Zener diode ZD1, in conjunction with transistors Q101 and Q102, is used to detect the power supply input voltage. When the voltage drops below 15V from Zener diode ZD1, an undervoltage and shutdown signal is sent to microcontroller U1.
[0009] The communication circuit includes an isolated transceiver U11, model TDA51S485HC. Pin 1 of the isolated transceiver U11 is connected to one end of capacitor C138, one end of capacitor E109, and VDD 3.3V. Pin 2 of the isolated transceiver U11 is connected to the other ends of capacitor C138 and C139 and ground. Pin 3 of the isolated transceiver U11 is connected to pin 76 of microcontroller U1. Pins 4 and 5 of the isolated transceiver U11 are connected and connected to one end of resistor R311 and pin 81 of microcontroller U1. The other end of resistor R311 is connected to VDD 3.3V. Pin 6 of the isolated transceiver U11 is connected to pin 75 of microcontroller U1. Pin 12 of the isolated transceiver U11 is connected to one end of resistor R608. Pin 13 of the isolated transceiver U11 is connected to one end of resistor R607. The other end of resistor R608 is connected to one end of resistor R107, the anode of Zener diode T202, and one end of fuse F102. The other end of resistor R107 outputs VCC3. The other end of resistor R607 is connected to one end of resistor R106, one end of fuse F101, and the cathode of Zener diode T202. Pin 15 of the isolated transceiver U11 is connected to one end of capacitor C139, one end of capacitor E110, and the other end of resistor R106. The other ends of capacitor C139 and capacitor E110 are connected to pin 16 of the isolated transceiver U11 and output VCC3. The other ends of fuse F101 and fuse F102 are connected to the host computer interface J5 through common mode inductor L5.
[0010] The power supply circuit includes a voltage regulator U3 that converts the power input DC+ to VCC and a voltage regulator U5 that converts VCC to VDD 3.3V, which are used for the normal power supply of the system.
[0011] The TFT screen driver interface circuit includes a TFT screen driver circuit and a TFT screen interface circuit. The TFT screen driver circuit includes an LED driver U2 and a boost converter U3. Pin 5 of the LED driver U2 is connected to one end of inductor L3, one end of capacitor E107, and VCC. The other end of capacitor E107 is grounded. Pin 4 of the LED driver U2 is connected to one end of resistor R309 and one end of resistor R803. The other end of resistor R309 is connected to pin 7 of the microcontroller U1. The other end of resistor R803 is grounded. Pin 1 of the LED driver U2 is connected to the anode of diode D201 and the other end of inductor L3. The cathode of diode D201 is connected to one end of capacitor C501 and pins 1 and 2 of TFT screen interface J6. The other end of capacitor C501 is connected to pin 2 of LED driver U2 and ground. Pin 3 of LED driver U2 is connected to one end of resistor R116. The other end of resistor R116 is connected to one end of resistor R10 and pins 3 and 4 of TFT screen interface J6. Pin 5 of boost converter U3 is connected to one end of inductor L5, one end of resistor R310, one end of capacitor C143, one end of capacitor E108, and VCC. Pin 4 of boost converter U3 is connected to the other end of resistor R310 and capacitor C143. The other end of the converter and the other end of capacitor E108 are both grounded. Pin 2 of the boost converter U3 is grounded, and pin 3 is connected to one end of resistor R702. The other end of resistor R702 is connected to one end of resistor R701, one end of capacitor C144, and one end of resistor R5. Pin 1 of the boost converter U3 is connected to the anode of diode D202, one end of capacitor C141, one end of capacitor C142, and the other end of inductor L5. The other end of capacitor C141 is connected to pin 3 of Schottky diode D501. Pin 2 of Schottky diode D501 is connected to one end of resistor R3 and one end of capacitor C145. The other end of resistor R3 is connected to resistor R... One end of R901, the cathode of Zener diode V1, one end of capacitor C601, one end of capacitor C502, one end of capacitor C147, and pin 41 of TFT screen interface J6 are connected. The other end of resistor R901, the anode of Zener diode V1, the other end of capacitor C601, the other end of capacitor C502, and the other end of capacitor C147 are all grounded. The other end of capacitor C145 is connected to pin 1 of Schottky diode D501, the cathode of diode D202, one end of resistor R701, one end of capacitor C144, one end of capacitor C504, one end of capacitor C603, and pin 43 of TFT screen interface J6. The other ends of resistor R5, capacitor C504, and capacitor C603 are all grounded. The other end of capacitor C142 is connected to pin 3 of Schottky diode D502. Pin 1 of Schottky diode D502 is connected to one end of capacitor C146 and one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R902, the anode of Zener diode V2, one end of capacitor C602, one end of capacitor C503, one end of capacitor C148, and pin 42 of TFT screen interface J6.Pin 2 of Schottky diode D502 is connected to the other end of capacitor C146, the other end of resistor R902, the cathode of Zener diode V2, the other end of capacitor C602, the other end of capacitor C503, and the other end of capacitor C148, all of which are grounded.
[0012] The TFT screen interface circuit includes a TFT screen interface J6. Ferrite beads are connected in series on the data bus and control signal link between the TFT screen interface J6 and the microcontroller U1, specifically as follows: pin 32 of the TFT screen interface J6 is connected to pin 46 of the microcontroller U1 via ferrite bead B101; pin 31 of the TFT screen interface J6 is connected to pin 41 of the microcontroller U1 via ferrite bead B102; pin 30 of the TFT screen interface J6 is connected to pin 26 of the microcontroller U1 via ferrite bead B103; and pin 29 of the TFT screen interface J6 is connected to... Connect pin 100 of microcontroller U1; pin 28 of TFT screen interface J6 is connected to pin 68 of microcontroller U1 via ferrite bead B105; pin 25 of TFT screen interface J6 is connected to pin 42 of microcontroller U1 via ferrite bead B106; pin 24 of TFT screen interface J6 is connected to pin 64 of microcontroller U1 via ferrite bead B107; pin 23 of TFT screen interface J6 is connected to pin 69 of microcontroller U1 via ferrite bead B108; and pin 22 of TFT screen interface J6 is connected to pin 70 of microcontroller U1 via ferrite bead B109. Pin 21 of TFT screen interface J6 is connected to pin 97 of microcontroller U1 via ferrite bead B110. Pin 20 of TFT screen interface J6 is connected to pin 93 of microcontroller U1 via ferrite bead B111. Pin 16 of TFT screen interface J6 is connected to pin 126 of microcontroller U1 via ferrite bead B112. Pin 15 of TFT screen interface J6 is connected to pin 65 of microcontroller U1 via ferrite bead B113. Pin 14 of TFT screen interface J6 is connected to pin 37 of microcontroller U1 via ferrite bead B114. Pin 13 of TFT screen interface J6 is connected to pin 97 of microcontroller U1 via ferrite bead B111. Pin 115 connects to pin 139 of microcontroller U1. Pin 12 of TFT screen interface J6 is connected to pin 140 of microcontroller U1 via ferrite bead B116. Pin 9 of TFT screen interface J6 is connected to pin 66 of microcontroller U1 via ferrite bead B117. Pin 10 of TFT screen interface J6 is connected to pin 40 of microcontroller U1 via ferrite bead B118. Pin 11 of TFT screen interface J6 is connected to pin 96 of microcontroller U1 via ferrite bead B119. Pin 37 of TFT screen interface J6 is connected to pin 67 of microcontroller U1 via ferrite bead B120.
[0013] The display and control link, as the "neural vision system" of the fire alarm system, is the core foundation for achieving efficient and reliable human-computer interaction and centralized management. This invention adopts a reinforced design with magnetic beads and isolation, which not only improves individual indicators, but also strategically strengthens the core functions and reliability of the system.
Claims
1. A display and control link protection circuit for a fire alarm system, comprising a system control circuit, a power supply circuit, a communication circuit, and a TFT screen driving interface circuit, wherein the control circuit includes a microcontroller U1, characterized in that, The communication circuit includes an isolated transceiver U11 of model TDA51S485HC. The TFT screen driving interface circuit includes a TFT screen driving circuit and a TFT screen interface circuit. The TFT screen interface circuit includes a TFT screen interface J6. The TFT screen interface J6 is connected to the microcontroller U1 via a data bus and a control signal link with a ferrite bead in series.
2. The display and control link protection circuit of a fire alarm system according to claim 1, characterized in that, The microcontroller U1 is an STM32H743ZI. Microcontroller U1 is connected to memory chips U7 and U6. Microcontroller U1 is also connected to a system detection circuit, which includes transistors Q101 and Q102. The base of transistor Q101 is connected to one end of resistor R208 and the collector of transistor Q102. The collector of transistor Q101 is connected to one end of resistor R207, one end of capacitor C11, and pin 43 of microcontroller U1. The resistor R... The other end of 207 and the other end of the resistor R208 are connected to VDD3.3V. The base of the transistor Q102 is connected to one end of the resistor R209 and one end of the resistor R210. The other end of the resistor R210 is connected to one end of the capacitor C153 and the anode of the Zener diode ZD1. The cathode of the Zener diode ZD1 is connected to the power supply input DC+. The other end of the capacitor C153, the other end of the resistor R209, the emitter of the transistor Q102, the emitter of the transistor Q101, and the other end of the capacitor C11 are all grounded.
3. The display and control link protection circuit of a fire alarm system according to claim 1, characterized in that, The power supply circuit includes a voltage regulator U3 that converts the power input DC+ to VCC and a voltage regulator U5 that converts VCC to VDD 3.3V.
4. The display and control link protection circuit of a fire alarm system according to claim 2, characterized in that, In the communication circuit, pin 1 of the isolated transceiver U11 is connected to one end of capacitor C138, one end of capacitor E109, and VDD 3.3V. Pin 2 of the isolated transceiver U11 is connected to the other ends of capacitor C138 and capacitor C139 and ground. Pin 3 of the isolated transceiver U11 is connected to pin 76 of the microcontroller U1. Pins 4 and 5 of the isolated transceiver U11 are connected and connected to one end of resistor R311 and pin 81 of the microcontroller U1. The other end of resistor R311 is connected to VDD 3.3V. Pin 6 of the isolated transceiver U11 is connected to pin 75 of the microcontroller U1. Pin 12 of the isolated transceiver U11 is connected to one end of resistor R608. Pin 13 of the isolated transceiver U11 is connected to... One end of resistor R607 is connected to one end of resistor R107, the anode of Zener diode T202, and one end of fuse F102. The other end of resistor R107 outputs VCC3. The other end of resistor R607 is connected to one end of resistor R106, one end of fuse F101, and the cathode of Zener diode T202. Pin 15 of isolated transceiver U11 is connected to one end of capacitor C139, one end of capacitor E110, and the other end of resistor R106. The other ends of capacitor C139 and capacitor E110 are connected to pin 16 of isolated transceiver U11 and output VCC3. The other ends of fuse F101 and fuse F102 are connected to host computer interface J5 through common mode inductor L5.
5. The display and control link protection circuit of a fire alarm system according to claim 2, characterized in that, The TFT screen driving circuit includes an LED driver U2 and a boost converter U3. Pin 5 of the LED driver U2 is connected to one end of inductor L3, one end of capacitor E107, and VCC. The other end of capacitor E107 is grounded. Pin 4 of the LED driver U2 is connected to one end of resistor R309 and one end of resistor R803. The other end of resistor R309 is connected to pin 7 of the microcontroller U1. The other end of resistor R803 is grounded. Pin 1 of the LED driver U2 is connected to the anode of diode D201 and the other end of inductor L3. The cathode of diode D201 is connected to capacitor C501. One end of the capacitor C501 is connected to pins 1 and 2 of the TFT screen interface J6. The other end of the capacitor C501 is connected to pin 2 of the LED driver U2 and ground. Pin 3 of the LED driver U2 is connected to one end of resistor R116. The other end of resistor R116 is connected to one end of resistor R10 and pins 3 and 4 of the TFT screen interface J6. Pin 5 of the boost converter U3 is connected to one end of inductor L5, one end of resistor R310, one end of capacitor C143, one end of capacitor E108, and VCC. Pin 4 of the boost converter U3 is connected to the other end of resistor R310. The other end of capacitor C143 and capacitor E108 are connected to... The other end of 108 is grounded. Pin 2 of the boost converter U3 is grounded, and pin 3 is connected to one end of resistor R702. The other end of resistor R702 is connected to one end of resistor R701, one end of capacitor C144, and one end of resistor R5. Pin 1 of the boost converter U3 is connected to the anode of diode D202, one end of capacitor C141, one end of capacitor C142, and the other end of inductor L5. The other end of capacitor C141 is connected to pin 3 of Schottky diode D501. Pin 2 of Schottky diode D501 is connected to one end of resistor R3 and one end of capacitor C145. The other end of resistor R3 is connected to resistor R90. One end of the capacitor is connected to the cathode of Zener diode V1, one end of capacitor C601, one end of capacitor C502, one end of capacitor C147, and pin 41 of the TFT screen interface J6. The other end of the resistor R901, the anode of Zener diode V1, the other end of capacitor C601, the other end of capacitor C502, and the other end of capacitor C147 are all grounded. The other end of capacitor C145 is connected to pin 1 of Schottky diode D501, the cathode of diode D202, one end of resistor R701, one end of capacitor C144, one end of capacitor C504, one end of capacitor C603, and pin 43 of the TFT screen interface J6. The other ends of resistor R5, capacitor C504, and capacitor C603 are all grounded. The other end of capacitor C142 is connected to pin 3 of Schottky diode D502. Pin 1 of Schottky diode D502 is connected to one end of capacitor C146 and one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R902, the anode of Zener diode V2, one end of capacitor C602, one end of capacitor C503, one end of capacitor C148, and pin 42 of TFT screen interface J6.Pin 2 of the Schottky diode D502 is connected to the other end of capacitor C146, the other end of resistor R902, the cathode of Zener diode V2, and the other ends of capacitors C602, C503, and C148, all of which are grounded.
6. The display and control link protection circuit of a fire alarm system according to claim 5, characterized in that, Pin 32 of the TFT screen interface J6 is connected to pin 46 of the microcontroller U1 via ferrite bead B101; pin 31 of the TFT screen interface J6 is connected to pin 41 of the microcontroller U1 via ferrite bead B102; pin 30 of the TFT screen interface J6 is connected to pin 26 of the microcontroller U1 via ferrite bead B103; pin 29 of the TFT screen interface J6 is connected to pin 100 of the microcontroller U1 via ferrite bead B104; and pin 28 of the TFT screen interface J6 is connected to pin 68 of the microcontroller U1 via ferrite bead B105. Pin 25 of the TFT screen interface J6 is connected to pin 42 of the microcontroller U1 via ferrite bead B106; pin 24 of the TFT screen interface J6 is connected to pin 64 of the microcontroller U1 via ferrite bead B107; pin 23 of the TFT screen interface J6 is connected to pin 69 of the microcontroller U1 via ferrite bead B108; pin 22 of the TFT screen interface J6 is connected to pin 70 of the microcontroller U1 via ferrite bead B109; and pin 21 of the TFT screen interface J6 is connected to pin 97 of the microcontroller U1 via ferrite bead B110. Pin 20 of the TFT screen interface J6 is connected to pin 93 of the microcontroller U1 via ferrite bead B111; pin 16 of the TFT screen interface J6 is connected to pin 126 of the microcontroller U1 via ferrite bead B112; pin 15 of the TFT screen interface J6 is connected to pin 65 of the microcontroller U1 via ferrite bead B113; pin 14 of the TFT screen interface J6 is connected to pin 37 of the microcontroller U1 via ferrite bead B114; and pin 13 of the TFT screen interface J6 is connected to pin 139 of the microcontroller U1 via ferrite bead B115. Pin 12 of the TFT screen interface J6 is connected to pin 140 of the microcontroller U1 via ferrite bead B116; pin 9 of the TFT screen interface J6 is connected to pin 66 of the microcontroller U1 via ferrite bead B117; pin 10 of the TFT screen interface J6 is connected to pin 40 of the microcontroller U1 via ferrite bead B118; pin 11 of the TFT screen interface J6 is connected to pin 96 of the microcontroller U1 via ferrite bead B119; and pin 37 of the TFT screen interface J6 is connected to pin 67 of the microcontroller U1 via ferrite bead B120.