dtoverlay=pwm-2chan has no effect on RPi 5

[schech1]

I added dtoverlay=pwm-2chan to /boot/config.txt on a Raspberry Pi 5, but lsmod | grep pwm does not show any output.
Also there is no pwm-signal generated either on GPIO19 or 18.

[CamDavidsonPilon]

Hi @schech1, are you using the latest version (0.2.1, check with pip list). If not, please upgrade. The RPi5 is supported by adding chip=2, ex: HardwarePWM(..., chip=2)

[schech1]

Yes, I'm using 0.2.1 and i also used chip=2.
I also believe that issue is not really related with rpi_hardware_pwm.
But should I see pwm_bcm2835 when using lsmod | grep pwm on a RPi5 after reboot?

[CamDavidsonPilon]

Testing on my Rpi5, no, I don't see lsmod | grep pwm return anything

[schech1]

I'm trying to figure out what I do wrong.
I connected an LED to GPIO 18 and ran this simple test:

from gpiozero import PWMLED
from rpi_hardware_pwm import HardwarePWM
from time import sleep

# Not working
pwm = HardwarePWM(pwm_channel=0, hz=60, chip=2)
pwm.start(100) 
sleep(2)
pwm.stop()

# Working
led = PWMLED(18, frequency = 200) 
led.value = 1
sleep(1)
led.value = 0

Using gpiozero on the same pin, it works.
Is there anything I can do to investigate further?

[CamDavidsonPilon]

hm, try the following in boot/config.txt (this is from my RPi5):

dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4

then try the same code, but targeting pin 12. Maybe something is different with the other pins?

[schech1]

Yeah, that works.
Got it working no on pin 12 and 13.

[CamDavidsonPilon]

Okay, interesting, something must be different with RPi5 for the original pins. I'll have to investigate later though.

[somsubhro88]

This solution works for me as well. Thank you for this library!!

[wayneOS1337]

I still got problems on Pi5.

config.txt:
dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4

python:
pwm = HardwarePWM(pwm_channel=1, hz=frequency, chip=2)
pwm.start(50)

I get no PWM output on Pin 13. What am i missing? Thanks in advance.

[CamDavidsonPilon]

@wayneOS1337 not sure - did you do a reboot? Can you paste here your entire config.txt file?

[wayneOS1337]

Yes, i did a reboot. My config.txt is:

# For more options and information see
# http://rptl.io/configtxt
# Some settings may impact device functionality. See link above for details

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

# Additional overlays and parameters are documented
# /boot/firmware/overlays/README

# Automatically load overlays for detected cameras
camera_auto_detect=1

# Automatically load overlays for detected DSI displays
display_auto_detect=1

# Automatically load initramfs files, if found
auto_initramfs=1

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers=2

# Don't have the firmware create an initial video= setting in cmdline.txt.
# Use the kernel's default instead.
disable_fw_kms_setup=1

# Run in 64-bit mode
arm_64bit=1

# Disable compensation for displays with overscan
disable_overscan=1

# Run as fast as firmware / board allows
arm_boost=1

[cm4]
# Enable host mode on the 2711 built-in XHCI USB controller.
# This line should be removed if the legacy DWC2 controller is required
# (e.g. for USB device mode) or if USB support is not required.
otg_mode=1

[all]
dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4

So basically i just added the pwm-2chan line on the end. I did this previously on a Pi4 and everythings was working smooth with "rpi_hardware_pwm".

But my guess is that the dtoverlay is not working correctly. After reboot i get for:

$ pinctrl get 12,13

12: no pd | -- // PIN32/GPIO12 = none
13: no pd | -- // PIN33/GPIO13 = none

i also tried to just use dtoverlay=pwm-2chan or dtoverlay=pwm in config.txt, to use it with the default GPIO 18 but to no avail.

[CamDavidsonPilon]

There is an errant ` at the end of the last line of your config.txt: is that a type in github or your config?

[wayneOS1337]

Yes, sorry that was a typo in my comment. i edited my comment. The file is without it.

[CamDavidsonPilon]

Not sure! How are you measuring PWM on a pin?

[wayneOS1337]

I tested it with a Servo (same settings as on the Pi4) and also with a LED. Did you use Bookworm as OS? or is there any additional Software i need to install?