I try both solutions. And still, I wasn´t able to set enable on pins 32, 33 and 35. After rebooting the system I was able to write to pmw0/enable (for pin33 and 32). However, for some reason, I still cannot write (write error: Invalid argument) to pmw1/enable for pin35.
Aditional info
Like @technoryt, I was always able to set period and duty_cycle for all pins. I only had issues while setting enable (echo 1 > /sys/class/pwm/pwmchip{x}/pwm[n}/enable ) for pins 32, 33 and 35.
I only have one active DTO each time. And I’m using rasbian.
Actually, I rebooted after using ldto merge (so that I do not need to use ldto activate, I don’t think I changed anything else). Now I can successfully use all four PWM lines. I started from the Ubuntu 22.04 Desktop image.
@Samuel: did you manage to use the PWM lines from a non-root user? If I try to add my user to the gpio group as mentioned by @librecomputer, I have the error that the group does not exist. All the directories under /sys/class/pwm are all owned by root:root.
ubuntu@lepotato:~$ sudo adduser ubuntu gpio
[sudo] password for ubuntu:
adduser: The group `gpio' does not exist.
@librecomputer: Regarding your last post. All the files under sys/class/pwm/pwmchip{X} belong to the gpio group. Except for the pwmchip{X}, which are owned by root group. So, I tried to change the group of these directories (assuming that it should be gpio) but nothing changed:
inl@raspberrypi:~ $ sudo chgrp gpio /sys/class/pwm/pwmchip0
inl@raspberrypi:~ $ ls -l /sys/class/pwm/
total 0
lrwxrwxrwx 1 root root 0 Jan 18 16:43 pwmchip0 → …/…/devices/platform/soc/c1100000.bus/c11086c0.pwm/pwm/pwmchip0
By way, it is not very clear to me which group should own these directories. Should It be gpio?
For some reason, now I can control pin35, but cannot control pin33 anymore (refer to my previous post). Why could this be?
@technoryt: Regarding your question, I believe so, at least for pins 12 and 13. Relative to your comment, my user was already a member of gpio group.
Hello, I am new to this space and have no idea what do I do. So I tried enabling pin 32 and 33.
ls -al /sys/class/pwm # see the pwmchip{n} to hardware mapping
echo {0,1} | sudo tee /sys/class/pwm/pwmchip0/export
echo 1000000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period
echo 500000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable
Overlay pwm-ef: already exists
total 0
drwxr-xr-x 2 root root 0 Dec 31 1969 .
drwxr-xr-x 75 root root 0 Dec 31 1969 ..
lrwxrwxrwx 1 root root 0 Apr 8 13:48 pwmchip0 -> ../../devices/platform/soc/c1100000.bus/c11086c0.pwm/pwm/pwmchip0
lrwxrwxrwx 1 root root 0 Apr 8 13:52 pwmchip2 -> ../../devices/platform/soc/c1100000.bus/c1108550.pwm/pwm/pwmchip2
0 1
tee: /sys/class/pwm/pwmchip0/export: Invalid argument
tee: /sys/class/pwm/pwmchip0/pwm0/period: No such file or directory
1000000
tee: /sys/class/pwm/pwmchip0/pwm0/duty_cycle: No such file or directory
500000
tee: /sys/class/pwm/pwmchip0/pwm0/enable: No such file or directory
1
I am not sure what is wrong and why, or even the right way to do that. Also, what do I use for python to control PWM? Is periphery good? Also weird thing is that It says in spreadsheet that port 32 is controlled by chip 1 and not 0…
You have to echo 0 or 1 based on which PWM you want to export. {0,1} is an invalid entry. You have to replace all things in {} with the proper value as outlined in the OP.
Ok that worked. But how do I control it? When I try using periphery, it gives me
periphery.pwm.PWMError: [Errno 19] Exporting PWM channel: No such device
I do not understand channels and how do I find right one for pin 32.
Here is what I got from activating pin 32:
yasushiko@raspberrypi:~ $ sudo ldto enable pwm-e # replace x with one of the dtos in list above
ls -al /sys/class/pwm # see the pwmchip to hardware mapping
echo 0 | sudo tee /sys/class/pwm/pwmchip0/export
echo 1000000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period
echo 500000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable
Overlay pwm-e: applied
total 0
drwxr-xr-x 2 root root 0 Dec 31 1969 .
drwxr-xr-x 87 root root 0 Dec 31 1969 ..
lrwxrwxrwx 1 root root 0 Apr 8 19:28 pwmchip0 -> ../../devices/platform/soc/c1100000.bus/c11086c0.pwm/pwm/pwmchip0
0
1000000
500000
1
But if I want to control it through periphery, how do I do that? I want to control Victor SPX. Also, could I control two of them at the same time? What is chip, and what is channel when I set up periphery in the code down below?
Either I am dumb or something is wrong. Here is code that I used and nothing happens… Code runes no errors but nothing mover or motor even detects PWM signal. Checked with Arduino, and all works with first try. I also tried running default code for periphery and did not work too. I enabled pwm on pin 32 and tried other pins. I also checked if pwmchip is mapping and it is. And I do not have an oscilloscope to check if anything comes out. I did not move jumper, do I need to? What am I doing wrong?
from periphery import PWM
import time
# Open PWM chip 0, channel 0
pwm = PWM(0, 0)
# Set frequency to 15 kHz
pwm.frequency = 15e3
# Enable PWM output
pwm.enable()
# Set duty cycle to 20%
pwm.duty_cycle = 0.20
# Wait for 10 seconds
time.sleep(10)
# Disable PWM output
pwm.disable()
# Close PWM
pwm.close()
I even tried rung by command line and here is what I got:
yasushiko@raspberrypi:~ $ sudo ldto enable pwm-e
ls -al /sys/class/pwm
echo 0 | sudo tee /sys/class/pwm/pwmchip0/export
echo 15000000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period
echo 7500000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable
Overlay pwm-e: applied
total 0
drwxr-xr-x 2 root root 0 Dec 31 1969 .
drwxr-xr-x 87 root root 0 Dec 31 1969 ..
lrwxrwxrwx 1 root root 0 Apr 12 21:22 pwmchip0 -> ../../devices/platform/soc/c1100000.bus/c11086c0.pwm/pwm/pwmchip0
0
15000000
7500000
1
But nothing happened. Controller continued blinking like I didn’t receive anything.
john@potato:~ $ echo 0 | sudo tee /sys/class/pwm/pwmchip0/export 0
john@potato:~ $ echo 1000000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period 1000000
john@potato:~ $ echo 500000 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle 500000
john@potato:~ $ echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable 1
I’m monitoring the pin with an oscilloscope and I’m not getting any output at all. I have tried a few different PWM pins and I’m getting the same experience across the board.
EDIT: I went through an tested every single pin and combination. pwm-a / pwm0 /pin33 seems to be working correctly. No others are.
So I’m trying to control a pwm fan on CoreELEC for AML-S905X-CC. The Wiring Tool explicitly states it is not supported on CoreELEC. The usual commands for libgpiod do not seem to be available. Only c11086c0.pwm seems to be listed in sysfs. The npwm for this chip indicates there are 4 pwm’s available on this chip. When exporting, pwm0 and 2 are busy, but 1 and 3 are available to be exported.
If I understand correctly, pwm1 on this chip should correspond to pin 35. I’ve read that 25khz is appropriate, so I’ve set the period to 40000, the duty_cycle to 20000 and enable to 1. Nothing seems to change.