Temperature transmitter hardware framework and schematic diagram

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Temperature transmitter hardware framework and schematic diagram [Copy link]

 

1. Hardware architecture:

I recently read the ADUCM360 data sheet in detail and found that some IO ports of the MCU can be configured as programmable excitation current source outputs. This can greatly simplify the design of complex precision current sources. Programmable excitation current source pins 12, 22, and 23 can all be configured as excitation current source outputs. Programmable excitation current range: 10uA-1000uA. Plus it has its own 24-bit high-precision ADC. The overall system architecture is simplified compared to the previous version, eliminating the precision current source design, op amp positive and negative power supply design, signal acquisition design, and expensive high-precision 24ADC. The attachment is the ADUCM360 data sheet and the new version of the schematic.

2. Code part

This part configures P1.3 as the system operation indicator LED output, initializes the system clock, configures the CPU, initializes the serial port, configures the ADC, configures the external excitation current source, and enables the ADC interrupt and the serial port interrupt.

The following procedure mainly completes four steps.

1. Measure the precise excitation current from AIN1 to AGND.

2. Measure the voltage from AIN0 to AGND.

3. Measure the voltage of the RTD between AIN1 and AIN0.

4. Calculate the RTD resistance and temperature values and print them out. P1.3 outputs LED to indicate program operation.

The code is based on the example of the board. The program is compiled correctly. After the RTD is printed out normally, additional posts will be added. After this part is completed, the IIC conversion to 4-20mA will be adjusted.

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