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products:sbc:common:applications:gpio:pwm

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products:sbc:common:applications:gpio:pwm [2023/03/30 23:52]
nick 		products:sbc:common:applications:gpio:pwm [2024/08/22 02:40] (current)
nick
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 ===== PWM Reference Table ===== ===== PWM Reference Table =====
  
-|           ^  PWM       ^  PIN  ^  GPIO name  ^  GPIO num  ^  DT overlay node  ^  Device node              ^ +|         ^  PWM           ^  PIN  ^  GPIO name      ^  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''   |  ''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''  |  ''pwm_d''        |  /sys/class/pwm/pwmchip1  | 
-^  VIM3/3L  |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  432          |  ''pwm_f''             |  /sys/class/pwm/pwmchip4  | +^  VIM3   |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  ''pwm_f''        |  /sys/class/pwm/pwmchip4  | 
-^  VIM4     |  ''PWM_F''     |  35   |  ''GPIOY_8''    |  482          |  ''pwm_f''             |  /sys/class/pwm/pwmchip4  | +^  VIM3L  |  ''PWM_F''     |  35   |  ''GPIOH_5''    |  ''pwm_f''        | /sys/class/pwm/pwmchip0   | 
-^  VIM1S    |  ''PWM_F''     |  35   |  ''GPIOZ_6''    |  503          |  ''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  |
  
  
 ===== Enable PWM ===== ===== Enable PWM =====
 +
 +==== Linux ====
 +
  
 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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 device  export  npwm  power  subsystem  uevent  unexport 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
 +
 +```
 +
 +After reboot, you will see the pwm device node.
  
 <tabbox VIM4> <tabbox VIM4>
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 </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]].+==== Android ==== 
 + 
 +<tabbox VIM4> 
 + 
 +The ''PWM'' function is disabled by default, you need to modify the dts to enable it. 
 + 
 +```diff 
 +diff --git a/arch/arm64/boot/dts/amlogic/kvim4.dts b/arch/arm64/boot/dts/amlogic/kvim4.dts 
 +--- a/arch/arm64/boot/dts/amlogic/kvim4.dts 
 ++++ b/arch/arm64/boot/dts/amlogic/kvim4.dts 
 + &pwm_ef { 
 ++    pinctrl-names = "default"; 
 ++    pinctrl-0 = <&pwm_f_pins>; 
 +        status = "okay"; 
 + }; 
 +  
 +diff --git a/arch/arm64/boot/dts/amlogic/kvim4n.dts b/arch/arm64/boot/dts/amlogic/kvim4n.dts 
 +--- a/arch/arm64/boot/dts/amlogic/kvim4n.dts 
 ++++ b/arch/arm64/boot/dts/amlogic/kvim4n.dts 
 + &pwm_ef { 
 ++    pinctrl-names = "default"; 
 ++    pinctrl-0 = <&pwm_f_pins>; 
 +        status = "okay"; 
 + }; 
 +  
 +diff --git a/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi b/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi 
 +--- a/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi 
 ++++ b/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi 
 +@@ -1442,13 +1442,13 @@ 
 +  
 +        backlight1{ 
 +                compatible = "amlogic, backlight-t7"; 
 +-               status = "okay"; 
 ++               status = "disabled"; 
 +                index = <1>; 
 +                key_valid = <0>; 
 +                pinctrl-names = "pwm_on", 
 +                                "pwm_off"; 
 +-               pinctrl-0 = <&pwm_f_pins>; 
 +-               pinctrl-1 = <&bl1_pwm_off_pins>; 
 +                pinctrl_version = <2>; /* for uboot */ 
 +                interrupts = <0 197 1 
 + 
 +``` 
 + 
 +<tabbox VIM1S> 
 + 
 +The ''PWM'' function is disabled by default, you need to modify the dts to enable it. 
 + 
 +```diff 
 +--- a/arch/arm64/boot/dts/amlogic/kvim1s.dts 
 ++++ b/arch/arm64/boot/dts/amlogic/kvim1s.dts 
 +@@ -1411,8 +1411,8 @@ 
 + }; 
 +  
 + &pwm_ef { 
 +-       /*pinctrl-0 = <&pwm_f_pins2>;*/ 
 +-       /*pinctrl-names = "default";*/ 
 ++       pinctrl-0 = <&pwm_f_pins2>; 
 ++       pinctrl-names = "default"; 
 +        status = "okay"; 
 + }; 
 + 
 +``` 
 +</tabbox>
  
 ===== Control PWM ===== ===== Control PWM =====
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 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 VIM3L>  
- 
-```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 
 ``` ```
  
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 ``` ```
  
-<tabbox VIM1S> +<tabbox VIM3L/1S> 
  
 ```shell ```shell
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 echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable
 ``` ```
 +
 </tabbox> </tabbox>
  
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 ```shell ```shell
 echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
-``` 
-<tabbox VIM3L>  
-```shell 
-echo 0 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable 
 ``` ```
 <tabbox VIM2>  <tabbox VIM2> 
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 echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
 ``` ```
-<tabbox VIM1S> +<tabbox VIM3L/1S> 
 ```shell ```shell
 echo 0 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable echo 0 | sudo tee /sys/class/pwm/pwmchip0/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: 2023/03/30 23:52 by nick

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