Preface

Make full use of PWM resources, increase isolation, control multi-channel stepper motors, servos, and also use PWM to control lights, fans, etc. In addition, add 232 communication, 485 communication, CAN communication, Lora module, etc., and increase AD acquisition. Convert, display the information to the OLED screen, and transmit it through various methods. Sensors that support SPI and IIC protocols can display and transmit the collected data~~~~

1.PWM output

The designed expansion board can be used for simple industrial control, integrating PWM output control stepper motors, servos, fans, light sources, etc. ~~~~ This time I only choose the PA8 output wave with adjustable duty cycle. Since I don’t have an oscilloscope at hand, I can only verify it by measuring the pin voltage change. Through two photoelectric channels, CN11 and CN12, CN11 triggers once, the duty cycle increases by 10%, CN12 triggers once, the duty cycle decreases by 10%, and prints out.

2. Communication interface

Various communication interfaces, the commonly used 232 interface is used to communicate with the host computer, 485, CAN communication is used for board-level communication, with strong anti-interference ability; the wireless serial port module can communicate over long distances within a certain range. ~~~~ This time for verification of 232 communication, 485 communication, and CAN communication, Lora needs at least two for testing. The cost is limited, so only one was used. The entire routine uses 232 communication. When CN11 is triggered, a CAN loopback experiment is performed and the received data is printed.

3. Sensor interface

Add IIC and SPI communication interfaces for communicating with corresponding modules, such as MPU6050 module, OLED display, etc. This time, the MPU6050 sensor based on IIC communication is verified. Enter the test command and read the six-axis raw data of the sensor and the internal temperature.

4.Isolate input

Four channels of optocoupler isolation input enable communication between sensors of different levels. Optoelectronics can be connected and used as position limits to cooperate with the use of motors to improve safety and reliability. Connect to 4 channels of photoelectric, and when triggered, the onboard red and blue indicator lights will flip.

5.AD collection

Adding an AD acquisition channel can collect temperature, light intensity, and output voltage. This time, the voltage value when the thermistor changes is collected. The test starts and prints the collected AD value and voltage value.

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