cape_enable=bone_capemgr.enable_partno=univ-all,BB-ADC,BB-PWM0,BB-PWM1,BB-PWM2
相当的内容:
因此,PWM接口已经配置好了!现在只需导出并使用PWM即可。例如,要访问pwm0:所有这5个都已在最新的映像下默认启用:
https://beagleboard.org/latest-images
对于PWM,请确保参考https://github.com/beagleboard/bb.org-overlays/blob/master/examples/cape-unversal-pwm.txt和config-pin pwm <pin#>..
root@beaglebone:~# cd /sys/class/pwm/pwmchip0
root@beaglebone:/sys/class/pwm/pwmchip0# ls
device export npwm power subsystem uevent unexport
root@beaglebone:/sys/class/pwm/pwmchip0# echo 0 > export
root@beaglebone:/sys/class/pwm/pwmchip0# ls
device export npwm power pwm-0:0 subsystem uevent unexport
root@beaglebone:/sys/class/pwm/pwmchip0# ls pwm-0:0
capture device duty_cycle enable period polarity power subsystem uevent
注意:如果引脚已被使用,您可能需要在/boot/uEnv.txt
中使用disable_uboot_overlay_video=1
禁用HDMI。
要确定PWM接口的引脚映射,请参阅我的后续帖子“BeagleBone Black(v4.14)上PWM芯片到引脚的映射”。
针对BeagleBone的Debian 10.3 buster版本,最新镜像给出了pwm输出的下一个引脚映射:
P8.13 corresponds to folder: /sys/class/pwm/pwm-6:1
P8.19 corresponds to folder: /sys/class/pwm/pwm-6:0
P9.14 corresponds to folder: /sys/class/pwm/pwm-3:0
P9.16 corresponds to folder: /sys/class/pwm/pwm-3:1
P9.21 corresponds to folder: /sys/class/pwm/pwm-1:1
P9.22 corresponds to folder: /sys/class/pwm/pwm-1:0
config-pin P8.13 pwm
config-pin P8.19 pwm
config-pin P9.14 pwm
config-pin P9.16 pwm
config-pin P9.21 pwm
config-pin P9.22 pwm
debian@beaglebone:~$ cd /sys/class/pwm/pwm-6:1
debian@beaglebone:~$ echo 250000 > duty_cycle
debian@beaglebone:~$ echo 1 > enable