I have a beagleboard rev c4.
I have a touchscreen controller that I connect to the expansion pins.
The thing is :
When I boot up my board from an external power, the touchscreen is not
detected but When after booting from an external power I press the
reset button, now my touchscreen is detected and work fine :
here the log :
When after booting from an external power :
[ 11.754638] ads7846 spi3.0: touchscreen, irq 293
[ 11.759521] ads7846 spi3.0: no device detected, test read result
after reset button :
[ 10.951934] ads7846 spi3.0: touchscreen, irq 293
[ 10.957275] input: ADS7846 Touchscreen as /devices/platform/
I found that the pin mmc2_dat3 is up since the begining when booting
from external power and when I press the reset button, this pin change
to low state and change again to up state after approximatively 11.5
So I think the controller needs a rising edge in order to work.
How can I make this rising edge on the mmc2_dat3 even if it is booting
up with external power ?
thank you !