i.MX6UL -- PWM用户空间使用方法

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开发平台： 珠海鼎芯D518--基于i.MX6UL

开发系统： Linux4.1.15

文件系统：Yocto-Busybox1.23

基于iMX的PWM使用方法，这里将以PWM2作为示例，以下为PWM部分设置示例及解析：

root@imx6ulevk:~# cat /sys/kernel/debug/pwm/*查看当前PWM设备 */

platform/20fc000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f8000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f4000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f0000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/208c000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/2088000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/2084000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/2080000.pwm, 1 PWM device

pwm-0 (backlight ): requested enabled

root@imx6ulevk:~#echo 0 >/sys/class/pwm/pwmchip1/export/*设置PWM输出，调出pwm0目录下设备节点，用于以下配置 */

root@imx6ulevk:~# cat /sys/kernel/debug/pwm

platform/20fc000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f8000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f4000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/20f0000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/208c000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/2088000.pwm, 1 PWM device

pwm-0 ((null) ):

platform/2084000.pwm, 1 PWM device

pwm-0 (sysfs ): requested enabled

platform/2080000.pwm, 1 PWM device

pwm-0 (backlight ): requested enabled

root@imx6ulevk:~#cat/sys/class/pwm/pwmchip1/pwm0/{enable,period,duty_cycle}/*查看PWM使能、一个周期时间、一个周期中ON时间 */

root@imx6ulevk:~#echo 1 >/sys/class/pwm/pwmchip1/pwm0/enable/*设置PWM2使能 */

root@imx6ulevk:~#echo 1000000 >/sys/class/pwm/pwmchip1/pwm0/period/*设置PWM2一个周期的持续时间，单位为ns，即1K Hz */

root@imx6ulevk:~#echo 500000 >/sys/class/pwm/pwmchip1/pwm0/duty_cycle/*设置一个周期中的”ON”时间，单位为ns，即占空比=duty_cycle/period=50% */

root@imx6ulevk:~#cat/sys/class/pwm/pwmchip1/pwm0/{enable,period,duty_cycle}

1000000

500000

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