PWM for PoE Hat

[jaysonsantos]

Hey there, had anyone any success enabling PWM to control a PoE hat [1]?

I tried a few overlays but no luck.

 

```

rock-3a-worker-1:overlay:# cat /boot/armbianEnv.txt
verbosity=1
bootlogo=false
overlay_prefix=rk35xx
fdtfile=rockchip/rk3568-rock-3a.dtb
rootdev=UUID=f0751d3c-c5c2-4ced-a989-772c2ad130a4
rootfstype=ext4
overlays=w1-gpio i2c7 i2c8
extraboardargs=nvme_core.default_ps_max_latency_us=0
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u

```

 

I also built mraa with the following:

 

```

IMRAA=ON FTDI4222=OFF BUILDCPP=ON BUILDTESTS=ON BUILDSWIG=ON USBPLAT=ON ONEWIRE=ON INSTALLTOOLS=ON BUILDSWIGPYTHON=ON \
      bash -c "./scripts/run-cmake.sh && make -Cbuild install"

```

but it won't show anything on gpio or pwm

```

mraa-gpio list
No Pins

```

Any other ideas there?

[1] Pinout ->  https://wiki.radxa.com/ROCKPI_23W_PoE_HAT 

[jaysonsantos]

I found the answer on radxa's forum [1] by amazingfate.

In order to make it, you need to enable amazingfate's overlay and then control the pwm, which can be done like this:

 

wget https://raw.githubusercontent.com/radxa/kernel/stable-4.19-rock3/arch/arm64/boot/dts/rockchip/overlay/rk3568-pwm8-m0-fan.dts
armbian-add-overlay rk3568-pwm8-m0-fan.dts

sudo cat > /etc/systemd/system/fan-control.service <<EOF
[Service]
RemainAfterExit=true
ExecStart=bash -exc '\
echo 0 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/export || true; \
echo 10000 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/period && \
echo 5000 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/duty_cycle && \
echo normal > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/polarity && \
echo 1 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/enable'
ExecStop=bash -exc 'echo 0 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/enable'

[Install]
WantedBy=multi-user.target
EOF

systemctl enable fan-control.service

reboot # so the overlay gets applied and the service start

 

[1] https://forum.radxa.com/t/armbian-for-rock-3a-unofficial-build-with-mainline-kernel/9434/45

[oneofthemany]

On 7/3/2022 at 4:46 PM, jaysonsantos said:

I found the answer on radxa's forum [1] by amazingfate.

In order to make it, you need to enable amazingfate's overlay and then control the pwm, which can be done like this:

 

wget https://raw.githubusercontent.com/radxa/kernel/stable-4.19-rock3/arch/arm64/boot/dts/rockchip/overlay/rk3568-pwm8-m0-fan.dts
armbian-add-overlay rk3568-pwm8-m0-fan.dts

sudo cat > /etc/systemd/system/fan-control.service <<EOF
[Service]
RemainAfterExit=true
ExecStart=bash -exc '\
echo 0 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/export || true; \
echo 10000 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/period && \
echo 5000 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/duty_cycle && \
echo normal > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/polarity && \
echo 1 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/enable'
ExecStop=bash -exc 'echo 0 > /sys/devices/platform/fe6f0000.pwm/pwm/pwmchip*/pwm0/enable'

[Install]
WantedBy=multi-user.target
EOF

systemctl enable fan-control.service

reboot # so the overlay gets applied and the service start

 

[1] https://forum.radxa.com/t/armbian-for-rock-3a-unofficial-build-with-mainline-kernel/9434/45

You have missed out the replace active with default in the dts file

Edited July 19, 2022 by oneofthemany
found the issue and wanted to inform the author