External control circuit for multiplexing chip pins as EPROM programming pins

Abstract

This utility model includes a voltage control circuit and an IIC level conversion circuit. The voltage control circuit includes resistors R116, R117, R118, R119, R120, R121, R122, and R123, transistors Q1 and Q2, MOSFETs U81 and U82, and diodes D1 and D2. The IIC level conversion circuit includes chips Ue4, Ue5, and U71, resistors R99 and R98. Pin 1 of chip U71 is connected to a 3.3V DC power supply, pins 2 and 3 are connected to the microcontroller's I / O pins, pin 4 is grounded, pin 5 is connected to the microcontroller, pin 6 is connected to resistor R99 and pin 1 of chip Ue5, pin 7 is connected to resistor R98 and pin 1 of chip Ue4, and pin 8 is connected to the other end of resistors R98 and R99, and also connected to the negative terminals of diodes D1 and D2.

Description

Technical Field

[0001] This utility model relates to an external control circuit that reuses chip pins as EPROM programming pins. Background Technology

[0002] The GXHT40 is a sensor chip with EPROM. The chip uses the IIC interface for communication. When it is necessary to write data to the EPROM of the chip Ue4, a 7V voltage needs to be applied to the SDA terminal of the sensor after the data to be written is sent through the IIC pin.

[0003] The current solution is to use a switching power supply to switch between different power supplies to meet the chip programming conditions. However, the chip needs to be programmed with a lot of data, and this solution takes a lot of time to switch the voltage to a stable state. Summary of the Invention

[0004] To address the above issues, this solution proposes an external control circuit that reuses chip pins as EPROM programming pins. This circuit enables rapid voltage switching and significantly reduces chip testing time during production.

[0005] The purpose of this utility model is achieved as follows: An external control circuit that reuses chip pins as EPROM programming pins includes a voltage control circuit and an IIC level conversion circuit; The voltage control circuit includes resistors R116, R117, R118, R119, R120, R121, R122, and R123; transistors Q1 and Q2; MOSFETs U81 and U82; and diodes D1 and D2. 1_WIRE_PU_2 is connected to one end of resistors R118 and R120 and is connected to the microcontroller's I / O. The other end of resistor R120 is connected to GND. The other end of resistor R118 is connected to the base of transistor Q1. The emitter of transistor Q1 is connected to GND. The collector of transistor Q1 is connected to one end of resistors R116 and R122. The other end of resistor R116 is connected to the DC 5V power supply D5V. The other end of resistor R122 is connected to the gate of MOSFET U81. The source of MOSFET U81 is connected to the DC 5V power supply D5V. The drain of MOSFET U81 is connected to the positive terminal of transistor D1. 1_WIRE_PU_1 is connected to one end of resistors R119 and R121 and is connected to the microcontroller's I / O. The other end of resistor R121 is connected to GND. The other end of resistor R119 is connected to the base of transistor Q2. The emitter of transistor Q2 is connected to GND. The collector of transistor Q2 is connected to one end of resistors R117 and R123. The other end of resistor R117 is connected to the DC 5V power supply D5V. The other end of resistor R123 is connected to the gate of MOSFET U82. The source of MOSFET U82 is connected to the DC 7V power supply D7V. The drain of MOSFET U82 is connected to the positive terminal of transistor D2. The IIC level conversion circuit contains chips Ue4, Ue5, U71, resistors R99 and R98. Pin 1 of chip U71 is connected to a 3.3V DC power supply, pins 2 and 3 are connected to the microcontroller's I / O, pin 4 is grounded, pin 5 is connected to the microcontroller, and pin 5 can control chip U71 to turn on or off. Pin 6 is connected to resistor R99 and pin 1 of chip Ue5, pin 7 is connected to resistor R98 and pin 1 of chip Ue4, and pin 8 is connected to the other end of resistors R98 and R99, and is also connected to the cathode of diodes D1 and D2. Pin 2 of chip Ue4 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V. Pin 2 of chip Ue5 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V.

[0006] Chips Ue4 and Ue5 are small-volume temperature and humidity sensor chips with EPROM, namely GXHT40 chips.

[0007] Chip U71 is a level conversion chip, model number TCA9617ADGKR.

[0008] Compared with the prior art, the beneficial effects of this utility model are: This utility model relates to an external control circuit that reuses chip pins as EPROM programming pins. It can quickly switch voltages, significantly shortening chip testing time during production. Furthermore, it ensures that the microcontroller is unaffected by voltage switching while rapidly switching between 5V and 7V voltages to quickly program the internal EPROM of the GXHT40. In addition, the control circuit is simple, reliable, and inexpensive, greatly improving production efficiency with minimal cost. Attached Figure Description

[0009] Figure 1 This is a circuit diagram of an external control circuit for reusing chip pins as EPROM programming pins according to the present invention.

[0010] Among them: resistors R116, R117, R118, R119, R120, R121, R122, R123, transistor Q1, transistor Q2, diode D1, diode D2, resistor R99, and resistor R98. Detailed Implementation

[0011] See Figure 1 This utility model relates to an external control circuit for multiplexing chip pins as EPROM programming pins, including a voltage control circuit and an IIC level conversion circuit.

[0012] The voltage control circuit includes resistors R116, R117, R118, R119, R120, R121, R122, and R123, transistors Q1 and Q2, MOSFETs U81 and U82, and diodes D1 and D2.

[0013] 1_WIRE_PU_2 is connected to one end of resistors R118 and R120 and is connected to the microcontroller's I / O. The other end of resistor R120 is connected to GND. The other end of resistor R118 is connected to the base of transistor Q1. The emitter of transistor Q1 is connected to GND. The collector of transistor Q1 is connected to one end of resistors R116 and R122. The other end of resistor R116 is connected to the DC 5V power supply D5V. The other end of resistor R122 is connected to the gate of MOSFET U81. The source of MOSFET U81 is connected to the DC 5V power supply D5V. The drain of MOSFET U81 is connected to the positive terminal of transistor D1.

[0014] 1_WIRE_PU_1 is connected to one end of resistors R119 and R121 and is connected to the microcontroller's I / O. The other end of resistor R121 is connected to GND. The other end of resistor R119 is connected to the base of transistor Q2. The emitter of transistor Q2 is connected to GND. The collector of transistor Q2 is connected to one end of resistors R117 and R123. The other end of resistor R117 is connected to the DC 5V power supply D5V. The other end of resistor R123 is connected to the gate of MOSFET U82. The source of MOSFET U82 is connected to the DC 7V power supply D7V. The drain of MOSFET U82 is connected to the positive terminal of transistor D2.

[0015] In this way, transistors Q1 and Q2 are connected to the two pins 1_WIRE_PU_2 and 1_WIRE_PU_1, and the 5V and 7V voltages are switched through these two pins.

[0016] The IIC level conversion circuit includes chips Ue4, Ue5, and U71, resistors R99 and R98. Chips Ue4 and Ue5 are small-volume temperature and humidity sensor chips (GXHT40) with EPROM. Chip U71 is a level conversion chip, model TCA9617ADGKR. Because the microcontroller's I / O is connected to the IIC interface of Ue4, but the microcontroller's I / O port cannot withstand 7V, a level conversion circuit is needed between them to ensure that the microcontroller's I / O port always maintains a 3.3V level. The chips use the IIC interface for communication. When data needs to be written to the EPROM of chips Ue4 and Ue5, 7V voltage needs to be applied to the SDA terminal of the sensor after the data is sent through the IIC pin.

[0017] Pin 1 of chip U71 is connected to a 3.3V DC power supply, pins 2 and 3 are connected to the microcontroller's I / O, pin 4 is grounded, and pin 5 is connected to the microcontroller. Pin 5 can control chip U71 to turn on or off. Pin 6 is connected to resistor R99 and pin 1 of chip Ue5. Pin 7 is connected to resistor R98 and pin 1 of chip Ue4. Pin 8 is connected to the other end of resistors R98 and R99, and is also connected to the cathode of diodes D1 and D2.

[0018] Pin 2 of chip Ue4 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V.

[0019] Pin 2 of chip Ue5 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V.

[0020] The working principle of this control circuit is: by controlling the opening and closing of MOSFETs U81 and U82, the switching between 5V and 7V power supplies is controlled.

[0021] When the microcontroller sets 1_WIRE_PU_2 to high level and 1_WIRE_PU_1 to low level, MOSFET U81 is turned on and MOSFET U82 is turned off. Pin 8 of chip U71 is connected to a DC 5V voltage. Diodes D1 and D2 can prevent reverse current flow. At this time, the microcontroller can communicate normally with chips Ue4 and Ue5.

[0022] When programming the EPROMs of chips Ue4 and Ue5, the microcontroller controls 1_WIRE_PU_2 to low and 1_WIRE_PU_1 to high. This turns off MOSFET U81 and turns on MOSFET U82. Pin 8 of chip U71 is connected to a 7V DC voltage. Diodes D1 and D2 prevent reverse current flow. At this time, the microcontroller can control chip U71 to turn off via pin 5. The 7V voltage will not affect the microcontroller. Pin 1 of chips Ue4 and Ue5 is connected to 7V, allowing for normal EPROM programming. The programming process takes 2 milliseconds; therefore, the states of MOSFETs U81 and U82 should be switched back after 2 milliseconds.

Claims

1. An external control circuit for multiplexing chip pins as EPROM programming pins, characterized in that, Includes voltage control circuitry and IIC level conversion circuitry; The voltage control circuit includes resistors (R116), (R117), (R118), (R119), (R120), (R121), (R122), (R123), transistors (Q1), (Q2), MOSFETs U81 and U82, diodes (D1) and (D2). 1_WIRE_PU_2 is connected to one end of resistors (R118) and (R120) and is connected to the microcontroller's I / O. The other end of resistor (R120) is connected to GND. The other end of resistor (R118) is connected to the base of transistor (Q1). The emitter of transistor (Q1) is connected to GND. The collector of transistor (Q1) is connected to one end of resistors (R116) and (R122). The other end of resistor (R116) is connected to the DC 5V power supply D5V. The other end of resistor (R122) is connected to the gate of MOSFET U81. The source of MOSFET U81 is connected to the DC 5V power supply D5V. The drain of MOSFET U81 is connected to the positive terminal of transistor (D1). 1_WIRE_PU_1 is connected to one end of resistors (R119) and (R121) and is connected to the microcontroller's I / O. The other end of resistor (R121) is connected to GND. The other end of resistor (R119) is connected to the base of transistor (Q2). The emitter of transistor (Q2) is connected to GND. The collector of transistor (Q2) is connected to one end of resistors (R117) and (R123). The other end of resistor (R117) is connected to the DC 5V power supply D5V. The other end of resistor (R123) is connected to the gate of MOSFET U82. The source of MOSFET U82 is connected to the DC 7V power supply D7V. The drain of MOSFET U82 is connected to the positive terminal of transistor (D2). The IIC level conversion circuit contains chips Ue4, Ue5, U71, resistors (R99) and (R98). Pin 1 of chip U71 is connected to a 3.3V DC power supply, pins 2 and 3 are connected to the microcontroller's I / O, pin 4 is grounded, pin 5 is connected to the microcontroller, and pin 5 can control chip U71 to turn on or off. Pin 6 is connected to resistor (R99) and pin 1 of chip Ue5, pin 7 is connected to resistor (R98) and pin 1 of chip Ue4, and pin 8 is connected to the other end of resistor (R98) and resistor (R99), and is also connected to the cathode of diode (D1) and diode (D2). Pin 2 of chip Ue4 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V. Pin 2 of chip Ue5 is connected to the microcontroller's I / O, pins 4 and 5 are connected to GND, and pin 3 is connected to the 5V DC power supply D5V.

2. The external control circuit for multiplexing chip pins as EPROM programming pins according to claim 1, characterized in that, Chips Ue4 and Ue5 are small-volume temperature and humidity sensor chips with EPROM, namely GXHT40 chips.

3. The external control circuit for multiplexing chip pins as EPROM programming pins according to claim 1, characterized in that, Chip U71 is a level conversion chip, model number TCA9617ADGKR.

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