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Posted

With a little shell script I can switch gpio6 on/off:

#!/bin/sh

# PWM1 / GPIOA6
P=6

G="/sys/class/gpio/gpio${P}"

if [ ! -d "${G}" ]; then
  echo "Exporting GPIO${P}"
  echo ${P} > /sys/class/gpio/export
  echo out > ${G}/direction
fi

i=100
while [ "$i" -gt 0 ]; do
  i=`expr $i - 1`
  sleep .2
  echo 1 > ${G}/value
  sleep .1
  echo 0 > ${G}/value
done

if [ -d "${G}" ]; then
  echo "Unexporting GPIO${P}"
  echo ${P} > /sys/class/gpio/unexport
fi

but I dont see anything which could enable PWM on this pin:

root@nanopineo:~# ll /sys/class/gpio/gpio6/
total 0
-rw-r--r-- 1 root root 4096 Feb 21 11:38 active_low
lrwxrwxrwx 1 root root    0 Feb 21 11:38 device -> ../../../sunxi-pinctrl
-rw-r--r-- 1 root root 4096 Feb 21 11:37 direction
-rw-r--r-- 1 root root 4096 Feb 21 11:38 edge
drwxr-xr-x 2 root root    0 Feb 21 11:38 power
lrwxrwxrwx 1 root root    0 Feb 21 11:38 subsystem -> ../../../../../class/gpio
-rw-r--r-- 1 root root 4096 Feb 21 11:37 uevent
-rw-r--r-- 1 root root 4096 Feb 21 11:38 value

Is it possibe to enable PWM on the NanoPi Neo via sysfs?

 
Posted

The above link looks to be exactly what I was looking for back in the summer and failed on.

I didn't realize that if the pins were multiplexed they needed configuring in the kernel.

PWM is important to me for a number of reasons. I'll be giving this a go.

 

The link talks to legacy kernel with .fex files.

I presume there is a similar tweak to Device Tree for Development kernel which I have been a bit Leary of due to there only being 24 hours in a day.

Anyone able to offer some insights as to what to tweak if using the bleeding edge kernel?

 

Thanks

Allan

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