Linux驱动分析——PWM子系统

最新推荐文章于 2025-04-11 20:13:07 发布

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最新推荐文章于 2025-04-11 20:13:07 发布

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分类专栏： Linux

本文链接：https://blog.youkuaiyun.com/fang_yang_wa/article/details/112835157

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本文档主要介绍了在Linux系统中使用PWM的步骤，包括如何通过sysfs接口控制PWM输出，设备树中PWM的声明方法，以及STM32 PWM驱动的基本概念。在设备树中，PWM节点必须作为STM32定时器节点的子节点存在，并且需要注意引脚的复用情况。文中还提到了在特定情况下，多个PWM通道的配置问题。

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stm32mp157 盘古开发板 Linux内核版本4.19

1、首先了解在Linux系统上面怎么使用PWM，比如设置某个引脚输出某个PWM脉冲

内核文档linux-st\Documentation\ABI\testing\sysfs-class-pwm描述：

What:		/sys/class/pwm/
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		The pwm/ class sub-directory belongs to the Generic PWM
		Framework and provides a sysfs interface for using PWM
		channels.

What:		/sys/class/pwm/pwmchipN/
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		A /sys/class/pwm/pwmchipN directory is created for each
		probed PWM controller/chip where N is the base of the
		PWM chip.

What:		/sys/class/pwm/pwmchipN/npwm
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		The number of PWM channels supported by the PWM chip.

What:		/sys/class/pwm/pwmchipN/export
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		Exports a PWM channel from the PWM chip for sysfs control.
		Value is between 0 and /sys/class/pwm/pwmchipN/npwm - 1.

What:		/sys/class/pwm/pwmchipN/unexport
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		Unexports a PWM channel.

What:		/sys/class/pwm/pwmchipN/pwmX
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		A /sys/class/pwm/pwmchipN/pwmX directory is created for
		each exported PWM channel where X is the exported PWM
		channel number.

What:		/sys/class/pwm/pwmchipN/pwmX/period
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		Sets the PWM signal period in nanoseconds.

What:		/sys/class/pwm/pwmchipN/pwmX/duty_cycle
Date:		May 2013
KernelVersion:	3.11
Contact:	H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
		Sets the PWM signal dut

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