problem with GPIO 117


I try to turn a led manually on and off.
The led is connected in P9_25 that is gpio117.
So I execute the following lines in beaglebone’s terminal:

cd /sys/class/gpio
echo 117 > export
cd gpio117
echo out > direction
echo 1 > value


But the led is always on.

I measured the voltage with a digital mutimeter and it was 1.66V for both values 1 and 0.

Do you have any idea on what could be the problem?

P9_25 is GPIO3_21, which is also muxed with MCASP0 clock pin (MCASP0_ACLKX).
The 24.576MHz external oscillator (Y4) needs to be disable by software for proper functioning the pin P9_25 as GPIO.


Please show us the pinmux settings for your GPIO3_21 pin as well.