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products:sbc:common:applications:gpio:pwm
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Table of Contents
PWM
Introduction
This document mainly describes the usage of hardware PWM. You will learn how to control the hardware PWM on the 40-Pin Header.
PWM Information
VIM1
| PWM | PIN & GPIO Number | DT Overlays Node | Device Node |
|---|---|---|---|
| PWM_AO_A | PIN35 - GPIOAO_3 (#504) | pwm_ao_a | /sys/class/pwm/pwmchip4 |
VIM2
| PWM | PIN & GPIO Number | DT Overlays Node | Device Node |
|---|---|---|---|
| PWM_D | PIN35 - GPIODV_28 (#478) | pwm_d | /sys/class/pwm/pwmchip1/pwm1 |
VIM3/3L
| I2C | PIN & GPIO Number | DT Overlays Node | Bus Number | Device Node |
|---|---|---|---|---|
| I2CM 3 | SCL(22) - GPIOA_15 (#475) SDA(23) - GPIOA_14 (#474) | i2c3 | 3 | /dev/i2c-3 |
VIM4
| I2C | PIN & GPIO Number | DT Overlays Node | Bus Number | Device Node |
|---|---|---|---|---|
| I2CM F | SCL(22) - GPIOY_17 (#501) SDA (23) - GPIOY_18 (#502) | i2cm_f | 5 | /dev/i2c-5 |
| I2CM A | SCL(25) - GPIOT_20 (#466) SDA(26) - GPIOT_21 (#467) | i2cm_a | 0 | /dev/i2c-0 |
Enable PWM
VIM1/3/3L/4
PWM_F:
$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/export $ echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period $ echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle $ echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
VIM2
PWM_D:
$ echo 1 | sudo tee /sys/class/pwm/pwmchip1/export $ echo 1000000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/period $ echo 500000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/duty_cycle $ echo 1 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
Use an oscilloscope to check if the pins have been successfully enabled.
If you use an oscilloscope to view the PWM waveform, remember that the SBC and the oscilloscope need to share the same GND (ground).
Disable PWM
VIM1/3/3L/4
$ echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
VIM2
$ echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
Last modified: 2022/07/12 05:52 by nick