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products:sbc:common:applications:gpio:pwm

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products:sbc:common:applications:gpio:pwm [2022/07/12 06:32]
nick 		products:sbc:common:applications:gpio:pwm [2023/03/30 06:35]
ivan [PWM Reference Table]
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 ===== Introduction ===== ===== Introduction =====
  
-This document mainly describes the usage of hardware PWM. You will learn how to control the hardware PWM on the [[products:sbc:common:applications:gpio:40pin-header|40-Pin Header]].+This page introduces the usage of hardware PWM, and leads you to control the hardware PWM on the [[products:sbc:common:applications:gpio:40pin-header|40-Pin Header]].
  
-===== PWM Information =====+===== PWM Reference Table =====
  
-|           ^  PWM       ^  PIN  ^  GPIO Number       ^  DT Overlays Node  ^  Device Node              ^ +|           ^  PWM       ^  PIN  ^  GPIO name  ^  GPIO num  ^  DT overlay node  ^  Device node              ^ 
-^  VIM1     |  PWM_AO_A  |  35   |  GPIOAO_3 (#504)   |  pwm_ao_a          |  /sys/class/pwm/pwmchip4  | +^  VIM1     |  ''PWM_AO_A''  |  35   |  ''GPIOAO_3''   |  504          |  ''pwm_ao_a''          |  /sys/class/pwm/pwmchip4  | 
-^  VIM2     |  PWM_D     |  35   |  GPIODV_28 (#478)  |  pwm_d             |  /sys/class/pwm/pwmchip1  | +^  VIM2     |  ''PWM_D''     |  35   |  ''GPIODV_28''  |  478          |  ''pwm_d''             |  /sys/class/pwm/pwmchip1  | 
-^  VIM3/3L  |  PWM_F     |  35   |  GPIOX_7 (#432)    |  pwm_f             |  /sys/class/pwm/pwmchip4  | +^  VIM3/3L  |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  432          |  ''pwm_f''             |  /sys/class/pwm/pwmchip4  | 
-^  VIM4     |  PWM_F     |  35   |  GPIOY_8 (#482)    |  pwm_f             |  /sys/class/pwm/pwmchip4  |+^  VIM4     |  ''PWM_F''     |  35   |  ''GPIOY_8''    |  482          |  ''pwm_f''             |  /sys/class/pwm/pwmchip4  | 
 +^  VIM1S    |  ''PWM_F''     |  35   |  ''GPIOZ_6''    |  503          |  ''pwm_f''             |  /sys/class/pwm/pwmchip0  |
  
-===== Enabel PWM =====+ 
 +===== Enable PWM =====
  
 In order to use the PWM, you need to enable the PWM function via [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]]. In order to use the PWM, you need to enable the PWM function via [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]].
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 ``` ```
  
 +<tabbox VIM1S>
 +
 +Edit ''/boot/dtb/amlogic/kvim1s.dtb.overlay.env'' to add pwm node to ''fdt_overlays'' node if it doesn't exist.
 +
 +
 +You need to add ''pwm_f'' to node ''fdt_overlays'' if it doesn't exist to enable ''PWM_F''.
 +
 +```shell
 +fdt_overlays=pwm_f
 +
 +```
 +
 +After reboot, you will see the pwm device node.
 +
 +```shell
 +$ ls /sys/class/pwm/pwmchip0
 +device  export  npwm  power  subsystem  uevent  unexport
 +```
 </tabbox> </tabbox>
  
 ===== Disable PWM to Use GPIO ===== ===== Disable PWM to Use GPIO =====
  
-If you want to use normal GPIO instead of PWM, you can remove the PWM node in device tree overlays configration file. +If you want to use normal GPIO instead of PWM, you can remove the PWM node in [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]].
  
 ===== Control PWM ===== ===== Control PWM =====
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 ```shell ```shell
-$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/export +echo 1 | sudo tee /sys/class/pwm/pwmchip4/export 
-$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period +echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period 
-$ echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle +echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle 
-$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable+echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
 ``` ```
 <tabbox VIM2>  <tabbox VIM2> 
  
 ```shell ```shell
-$ echo 1 | sudo tee /sys/class/pwm/pwmchip1/export +echo 1 | sudo tee /sys/class/pwm/pwmchip1/export 
-$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/period +echo 1000000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/period 
-$ echo 500000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/duty_cycle +echo 500000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/duty_cycle 
-$ echo 1 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable+echo 1 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
 ``` ```
  
 +<tabbox VIM1S> 
 +
 +```shell
 +echo 1 | sudo tee /sys/class/pwm/pwmchip0/export
 +echo 1000000 | sudo tee /sys/class/pwm/pwmchip0/pwm1/period
 +echo 500000 | sudo tee /sys/class/pwm/pwmchip0/pwm1/duty_cycle
 +echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable
 +```
 </tabbox> </tabbox>
  
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 <tabbox VIM1/3/3L/4>  <tabbox VIM1/3/3L/4> 
 ```shell ```shell
-$ echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable+echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
 ``` ```
 <tabbox VIM2>  <tabbox VIM2> 
 ```shell ```shell
-$ echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable+echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable 
 +``` 
 +<tabbox VIM1S>  
 +```shell 
 +echo 0 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable
 ``` ```
 </tabbox> </tabbox>
  
  
Last modified: 2023/12/25 22:01 by jacobe

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