STM_ServoMotor

How to control a servo motor using NUCLEO-H743ZI2 board.

Hardware: NUCLEO-H743ZI2 board, servo motor(Tower Pro-MG 996R).
Software: STM32CubeMX and Keil uVision5.

STM32 Setting Parameter

System Clock = 32 MHz.
Prescaler = 640 - 1.
Counter Period = 1000 - 1.

Circuit

PWM control

Servo Motor Frequency = 50 Hz.
Pulse Width(0 to 180 degree):
- 1ms => -90 degree
- 1.5ms => 0 degree
- 2ms => 90 degree
Calculate worck cycle:
- 1ms => 1 / 20 * 100% = 5%
- 1.5ms => 1.5 / 20 * 100% = 7.5%
- 2ms => 2 / 20 * 100% = 10%
Calculate CCR:
- 1ms => 5% * 1000 = 50
- 1.5ms => 7.5% * 1000 = 75
- 2ms => 10% * 1000 = 100

Result

After testing it from 1 ms to 2ms, I found that the servo was not rotating the full 180 degrees as it should So I decided to take it a little further and tested it from 0.5 ms to 2.5 ms and It performed well. So the code below is for 0.5 to 2.5 ms, However I commented out the section for 1 to 2 ms.

Reference

[1]. Servo motor with STM32. https://controllerstech.com/servo-motor-with-stm32/

[2]. STM32H743ZI MCU. https://www.st.com/en/evaluation-tools/nucleo-h743zi.html

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