I'm looking into running some servos/ESC's from a new BeagleBone Black Rev
C. I've been all over the internet and have not found any updated info
about the BBB running Debian.
Here is what I've got so far:
1. /boot/uboot/uEnv.txt
1. Add optargs=capemgr.enable_partno=am33xx_pwm
1. shutdown -r time now
1. more /sys/devices/bone_capemgr.9/slots
root@beaglebone:/# more /sys/devices/bone_capemgr.9/slots
0: 54:PF---
1: 55:PF---
2: 56:PF---
3: 57:PF---
4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
7: ff:P-O-L Override Board Name,00A0,Override Manuf,am33xx_pwm
1. PWM is now configured on bootup.
I can now view the PWM hardware devices using this command:
root@beaglebone:/# more /sys/kernel/debug/pwm
platform/48304100.ecap, 1 PWM device
pwm-0 ((null) ):
platform/48304200.ehrpwm, 2 PWM devices
pwm-0 ((null) ):
pwm-1 ((null) ):
platform/48302200.ehrpwm, 2 PWM devices
pwm-0 ((null) ):
pwm-1 ((null) ):
platform/48300100.ecap, 1 PWM device
pwm-0 ((null) ):
platform/48300200.ehrpwm, 2 PWM devices
pwm-0 (sysfs ): requested enabled sysfs_exported
pwm-1 (sysfs ): requested enabled sysfs_exported
I've enabled 2 PWM outputs using these commands:
echo 0 > /sys/class/pwm/export
echo 1 > /sys/class/pwm/export
I can now view the PWM settings:
root@beaglebone:/sys/class/pwm/pwm0# dir
device duty_ns period_ns polarity power run subsystem uevent
root@beaglebone:/sys/class/pwm/pwm0# echo 20000000 >
period_ns // set period to 20ms
root@beaglebone:/sys/class/pwm/pwm0# echo 1000000 >
duty_ns // set duty cycle to 1ms
root@beaglebone:/sys/class/pwm/pwm0# echo 1 >
run // run the pwm
When I check the pins with my O-scope I get nothing. I think I am really
close but I can't figure out why they aren't outputting.
I've been reading a bunch of stuff about pin muxing, device tree overlays,
clock enabling... but I'm not sure what is up to date for BBB running
Debian 3.8.13 kernel
Anybody have any ideas?
Thanks,
Jay
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