1 2 3 4 5 6 7 8 9 | root@localhost:/boot/uboot# cd /sys/class/pwm/ root@localhost:/sys/class/pwm# ls pwmchip0 root@localhost:/sys/class/pwm# cd pwmchip0 root@localhost:/sys/class/pwm/pwmchip0# echo 18 > export bash: echo: write error: No such device root@localhost:/sys/class/pwm/pwmchip0# ls device export npwm power subsystem uevent unexport root@localhost:/sys/class/pwm/pwmchip0# |