GPIO in Kernel

    Dear support team,


    how can I control direction and value of the PicoMODs7A GPIOs in Kernel. The reason is we're using a beeper/buzzer on GPIO8. While uboot is running the output is low (beeper off). While Kernel is starting the output is high or connected as input (beeper off). In the rootfs I hav full control over the GPIO. So the questions is how to get control over the GPIOs in Kernel and if possible in uboot.


    Thanks for answers

    Are we talking about Pin 36 of the PicoMOD7A? By default this pin is configured as input with an internal pull-down. So the pin is low in U-Boot. The default kernel configuration has support for capacitive touch compiled in by default. Then this pin is the interrupt input for the touch controller and therefore it is configured as interrupt (=input) with pull-up. This is the reason why you see the pin toggling once when booting. If you remove the support for CONFIG_TOUCHSCREEN_ATMEL_MXT and CONFIG_TOUCHSCREEN_FT5X06 from the kernel configuration, then this pin will not be configured as touch interrupt and keeps its low-state all the time.

    F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.