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标题: AM57x PWM使用问题 [打印本页]

作者: czs----Tronlong 时间: 2020-4-22 17:53
标题: AM57x PWM使用问题
am5728上需要使用ehrpwm1a 和ehrpwm1b的功能，修改设备树，然后加载到开发板，reboot后，能显示pwm的设备节点，也可以配置，但是用示波器监控GPIO4_0和GPIO4_1，发现两个口上都没有PWM输出，请帮忙看看，配置有什么问题？谢谢！

//设备树增加如下的信息:
      ehrpwm0ab_pins: ehrpwm0ab_pins {
         pinctrl-single,pins = <
            DRA7XX_CORE_IOPAD(0x3564, PIN_OUTPUT | MUX_MODE10) /*vin2a_vsync0.ehrpwm1A*/
            DRA7XX_CORE_IOPAD(0x3568, PIN_OUTPUT | MUX_MODE10) /*vin2a_d0.ehrpwm1B*/
         >;
      };

&ehrpwm0 {
      status = "okay";
      pinctrl-names = "default";
      pinctrl-0 = <&ehrpwm0ab_pins>;
};

//设备树修改后,传入单板,reboot后，能显示pwm的信息，也可以配置
root@am57xx-evm:~# cd /sys/class/pwm
root@am57xx-evm:/sys/class/pwm# ls
pwmchip0  pwmchip2  pwmchip3
root@am57xx-evm:/sys/class/pwm#
root@am57xx-evm:/sys/class/pwm# cd pwmchip0
root@am57xx-evm:/sys/class/pwm/pwmchip0#
root@am57xx-evm:/sys/class/pwm/pwmchip0#
root@am57xx-evm:/sys/class/pwm/pwmchip0# cat npwm
2
root@am57xx-evm:/sys/class/pwm/pwmchip0#
root@am57xx-evm:/sys/class/pwm/pwmchip0#
root@am57xx-evm:/sys/class/pwm/pwmchip0# echo 0 > export
root@am57xx-evm:/sys/class/pwm/pwmchip0# echo 1 > export
root@am57xx-evm:/sys/class/pwm/pwmchip0# cd pwm0
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm0# echo 500000 > period
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm0# echo 250000 > duty_cycle
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm0# echo 1 > enable
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm0# cat {enable,period,duty_cycle}
1
500000
250000
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm0#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# echo 500000 > period
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# echo 250000 > duty_cycle
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# echo 1 > enable
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# cat {enable,period,duty_cycle}
1
500000
250000
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# cat /sys/kernel/debug/pwm
platform/dmtimer-pwm@16, 1 PWM device
pwm-0 (pwm_fan          ): requested enabled

platform/4843e100.ecap, 1 PWM device
pwm-0 (backlight          ): requested enabled

platform/4843e200.pwm, 2 PWM devices
pwm-0 (sysfs             ): requested enabled
pwm-1 (sysfs             ): requested enabled
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1#
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# devmem2 0x4a003564
/dev/mem opened.
Memory mapped at address 0xb6f25000.
Read at address  0x4A003564 (0xb6f25564): 0x0001000A
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1# devmem2 0x4a003568
/dev/mem opened.
Memory mapped at address 0xb6f86000.
Read at address  0x4A003568 (0xb6f86568): 0x0001000A
root@am57xx-evm:/sys/class/pwm/pwmchip0/pwm1

作者: lililala6868 时间: 2020-7-23 17:07
am5728上需要使用ehrpwm1a 和ehrpwm1b的功能，修改设备树，然后加载到开发板，reboot后，能显示pwm的设备节点，也可以配置，但是用示波器监控GPIO4_0和GPIO4_1

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