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products:sbc:common:applications:gpio:pwm

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products:sbc:common:applications:gpio:pwm [2022/07/12 05:54]
nick [Table] 		products:sbc:common:applications:gpio:pwm [2023/12/25 22:01] (current)
jacobe [Control PWM]
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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 =====
  
-<tabbox VIM1>+|         ^  PWM           ^  PIN  ^  GPIO name      ^  DT overlay node  ^  Device node              ^ 
 +^  VIM1   |  ''PWM_AO_A''  |  35   |  ''GPIOAO_3''   |  ''pwm_ao_a''     |  /sys/class/pwm/pwmchip4  | 
 +^  VIM2   |  ''PWM_D''     |  35   |  ''GPIODV_28''  |  ''pwm_d''        |  /sys/class/pwm/pwmchip1  | 
 +^  VIM3   |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  ''pwm_f''        |  /sys/class/pwm/pwmchip4  | 
 +^  VIM3L  |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  ''pwm_f''        | /sys/class/pwm/pwmchip0   | 
 +^  VIM4   |  ''PWM_F''     |  35   |  ''GPIOY_8''    |  ''pwm_f''        |  /sys/class/pwm/pwmchip4  | 
 +^  VIM1S  |  ''PWM_F''     |  35   |  ''GPIOZ_6''    |  ''pwm_f''        |  /sys/class/pwm/pwmchip0  |
  
-^  PWM      ^  PIN & GPIO Number       ^  DT Overlays Node  ^  Device Node              ^ 
-| PWM_AO_A  | PIN35 - GPIOAO_3 (#504)  |  pwm_ao_a          |  /sys/class/pwm/pwmchip4  | 
  
-<tabbox VIM2>+===== Enable PWM =====
  
-^  PWM   ^  PIN & GPIO Number        ^  DT Overlays Node  ^  Device Node              ^ +In order to use the PWM, you need to enable the PWM function via [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]].
-| PWM_D  | PIN35 - GPIODV_28 (#478)  |  pwm_d             |  /sys/class/pwm/pwmchip1  |+
  
-<tabbox VIM3/3L>+<tabbox VIM1/2/3/Edge1> 
 + 
 +Edit ''/boot/env.txt'' to add the pwm node to ''overlays'' node if it doesn't exist. 
 + 
 +Take VIM3 as an example to enable ''PWM_F'', you need to add ''pwm_f'' node to ''overlays'' node if it doesn't exist. 
 + 
 +```shell 
 +overlays=uart3 pwm_f i2c3 i2s os08a10 watchdog 
 +``` 
 + 
 +After reboot, you will see the pwm device node. 
 + 
 +```shell 
 +$ ls /sys/class/pwm/pwmchip4 
 +device  export  npwm  power  subsystem  uevent  unexport 
 +``` 
 + 
 +<tabbox VIM3L> 
 + 
 +Edit ''/boot/env.txt'' to add the pwm node to ''overlays'' node if it doesn't exist. 
 + 
 +Take VIM3L as an example to enable ''PWM_F'', you need to add ''pwm_f'' node to ''overlays'' node if it doesn't exist. 
 + 
 +```shell 
 +overlays=uart3 pwm_f i2c3 i2s watchdog 
 +``` 
 + 
 +After reboot, you will see the pwm device node. 
 + 
 +```shell 
 +$ ls /sys/class/pwm/pwmchip0 
 +device  export  npwm  power  subsystem  uevent  unexport 
 +``` 
 + 
 + 
 +<tabbox VIM3 with 5.15 kernel> 
 + 
 +Edit ''/boot/dtb/amlogic/kvim3.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. 
 + 
 +<tabbox VIM3L with 5.15 kernel> 
 + 
 +Edit ''/boot/dtb/amlogic/kvim3l.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 
 + 
 +```
  
-^  PWM   ^  PIN & GPIO Number      ^  DT Overlays Node  ^  Device Node              ^ +After reboot, you will see the pwm device node.
-| PWM_F  | PIN35 - GPIOX_7 (#432)  |  pwm_f             |  /sys/class/pwm/pwmchip4  |+
  
 <tabbox VIM4> <tabbox VIM4>
  
-^  PWM   ^  PIN & GPIO Number        ^  DT Overlays Node  ^  Device Node                   ^ +Edit ''/boot/dtb/amlogic/kvim4.dtb.overlay.env'' to add pwm node to ''fdt_overlays'' node if it doesn't exist.
-| PWM_D  | PIN35 - GPIODV_28 (#478)  |  pwm_d             |  /sys/class/pwm/pwmchip1/pwm1  |+
  
  
 +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/pwmchip4
 +device  export  npwm  power  subsystem  uevent  unexport
 +```
 +
 +<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>
  
-===== Enable PWM ===== 
  
-<tabbox VIM1/3/3L/4>  +===== Control PWM ===== 
-%%PWM_F:%%+ 
 +**Enable PWM:** 
 + 
 +<tabbox VIM1/3/4>  
 ```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> 
-PWM_D:+
 ```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 VIM3L/1S> 
 +
 +```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 VIM4/4N with 5.15 kernel> 
 +
 +```shell
 +echo 1 | sudo tee /sys/class/pwm/pwmchip12/export
 +echo 1000000 | sudo tee /sys/class/pwm/pwmchip12/pwm1/period
 +echo 500000 | sudo tee /sys/class/pwm/pwmchip12/pwm1/duty_cycle
 +echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm12/enable
 +```
 +
 </tabbox> </tabbox>
  
Line 58: Line 173:
 </WRAP> </WRAP>
  
-===== Disable PWM =====+**Disable PWM:**
  
-<tabbox VIM1/3/3L/4> +<tabbox VIM1/3/4> 
 ```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 VIM3L/1S> 
 +```shell
 +echo 0 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable
 +```
 +
 +<tabbox VIM4/4N with 5.15 kernel> 
 +```shell
 +echo 0 | sudo tee /sys/class/pwm/pwmchip12/pwm1/enable
 +```
 +
 </tabbox> </tabbox>
 +
 +===== Disable PWM to Use GPIO =====
 +
 +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]].
 +
  
  
Last modified: 2022/07/12 05:54 by nick

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