This is on BBB Linux beaglebone 4.14.108-ti-r108
On this new kernel I can see that cape_universal is being used in /boot/uEnv.txt so all, or quite of pwm’s
are on in /sys/class/pwm/pwmchip#
Some of the pwms like GPIO 71 P8-46 used to be on pwmchip6/pwm1
but now exporting 1 > gpiochip6 says no device.
Based on this utility https://redypis.org/addons/bb_pins.php which uses the bash array from config_pin I can see
that p8_46 is on 0x3:ehrpwm2B which is EHRPWM2 (ePWM2) which is pwmchip6 channel B
so export 1 (B) should work but now does not .
Furthermore more going to chips 6 folder and exporting 0 or un-exporting makes the gpio-6.0 going on and off which is fine, but
any attempt to write onto it fails
`
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 100000 ./duty_cycle
100000 ./duty_cycle
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 100000 > ./duty_cycle
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 100000 > enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 1 > enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ config-pin P8.46 pwm
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 1 > enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 0 > enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 0 > ./enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 10000 > enable
-bash: echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 10000 ./duty_cycle
10000 ./duty_cycle
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ echo 10000 > ./duty_cycle
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ sudo echo 1 > enable
[sudo] password for marius:
echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ sudo echo on > enable
echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ sudo echo default > enable
echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ sudo echo okay > enable
echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ sudo echo true > enable
echo: write error: Invalid argument
marius@beaglebone:/sys/class/pwm/pwmchip6/pwm-6:0$ uname -a
`
Is there any updated information or I have to look into the dts file and figure it out ?
Is there any way to find the mapping from the sys filesystem between the
KERNEL GPIO# – PX.Y (rail name) and /sys/class/pwm/pwm-X.Y
Thank you.