Difference between revisions of "PWM"
From FriendlyELEC WiKi
(updated by API) |
(updated by API) |
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| Line 5: | Line 5: | ||
https://github.com/torvalds/linux/commit/179a79fd740b6b2f66b64bae5cb6ecd483987d20 | https://github.com/torvalds/linux/commit/179a79fd740b6b2f66b64bae5cb6ecd483987d20 | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| + | 注: FriendlyELEC的内核源代码分支 https://github.com/friendlyarm/linux/tree/sunxi-4.14.y 已包含此提交。 | ||
====修改内核dts配置, 启用SYS_PWM (在NanoPi NEO上, 引脚与POWER LED复用)==== | ====修改内核dts配置, 启用SYS_PWM (在NanoPi NEO上, 引脚与POWER LED复用)==== | ||
参考以下补丁, 配置POWER LED对应的引脚为PWM功能，然后编译并测试: | 参考以下补丁, 配置POWER LED对应的引脚为PWM功能，然后编译并测试: | ||
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pinctrl-0 = <&leds_npi>, <&leds_r_npi>; | pinctrl-0 = <&leds_npi>, <&leds_r_npi>; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | ==== | + | ====测试脚本==== |
| + | 在NanoPi NEO上测试, 可看到POWER LED以淡出效果闪烁10次: | ||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
#!/bin/bash | #!/bin/bash | ||
Revision as of 10:59, 5 January 2022
Contents
1 H3上配置SYS_PWM
1.1 先确定内核已经打了这个补丁
https://github.com/torvalds/linux/commit/179a79fd740b6b2f66b64bae5cb6ecd483987d20
注: FriendlyELEC的内核源代码分支 https://github.com/friendlyarm/linux/tree/sunxi-4.14.y 已包含此提交。
1.2 修改内核dts配置, 启用SYS_PWM (在NanoPi NEO上, 引脚与POWER LED复用)
参考以下补丁, 配置POWER LED对应的引脚为PWM功能，然后编译并测试:
diff --git a/arch/arm/boot/dts/sun8i-h3-nanopi-neo.dts b/arch/arm/boot/dts/sun8i-h3-nanopi-neo.dts index b9826c150c0a..ca62502ad9a3 100644 --- a/arch/arm/boot/dts/sun8i-h3-nanopi-neo.dts +++ b/arch/arm/boot/dts/sun8i-h3-nanopi-neo.dts @@ -45,6 +45,10 @@ / { model = "FriendlyElec NanoPi-NEO"; compatible = "friendlyelec,nanopi-neo", "allwinner,sun8i-h3"; + + aliases { + pwm1 = &r_pwm; + }; }; &emac { @@ -52,4 +56,14 @@ phy-mode = "mii"; allwinner,leds-active-low; status = "okay"; -}; \ No newline at end of file +}; + +&gpio_leds { + pinctrl-0 = <&leds_npi>; + + /delete-node/ pwr; +}; + +&r_pwm { + status = "okay"; +}; diff --git a/arch/arm/boot/dts/sun8i-h3-nanopi.dtsi b/arch/arm/boot/dts/sun8i-h3-nanopi.dtsi index 5eeb41744735..1802f8ca2c56 100644 --- a/arch/arm/boot/dts/sun8i-h3-nanopi.dtsi +++ b/arch/arm/boot/dts/sun8i-h3-nanopi.dtsi @@ -89,7 +89,7 @@ }; }; - leds { + gpio_leds: leds { compatible = "gpio-leds"; pinctrl-names = "default"; pinctrl-0 = <&leds_npi>, <&leds_r_npi>;
1.3 测试脚本
在NanoPi NEO上测试, 可看到POWER LED以淡出效果闪烁10次:
#!/bin/bash sys_pwm=/sys/class/pwm/pwmchip0 [ -d $sys_pwm ] || exit 1 if [ ! -d $sys_pwm/pwm0 ]; then echo 0 > $sys_pwm/export fi echo 1000 > $sys_pwm/pwm0/period echo 1 > $sys_pwm/pwm0/enable for n in $(seq 10); do for d in $(seq 0 50 1000); do echo $d > $sys_pwm/pwm0/duty_cycle sleep .02 done sleep 1 done
