We’re evaluating the CC6 UL starter board for use with an RPi HAT. According to Digi’s documentation some of the GPIO1 pins on the expansion connector should be configured as GPIO by the default device tree. E.g. GPIO1_13 on Pin 12.
However, we can’t seem to control this pin and others on GPIO1 while e.g. those on GPIO3 work just fine.
Steps to reproduce (with no HAT connected):
- create a test project using mkproject.sh -p ccimx6ulstarter
- bitbake core-image-base
- copy zImage-ccimx6ulstarter.bin, imx6ul-ccimx6ulstarter-id129.dtb and core-image-base-ccimx6ulstarter.tar.bz2 to their respective target locations
- on the target
echo 13 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio13/direction
echo 0 > /sys/class/gpio/gpio13/value
-> The pin remains high instead of changing to low. The same works as expected when applied to e.g. GPIO3_4 (gpio68).
Any ideas what we’re missing here?
Edit: On further analysis I found out that the other ccimx6ulstarter .dts actually contain configurations for the Expansion Connector, just not the id129 variant. However, the board identifies as id 129 in the bootloader. If I copy and rename imx6ul-ccimx6ulstarter-wb.dts instead, everything seems to work as expected.
So I guess my question is why does the -id129 variant not include the Expansion Connector in the dts even though the starter board has it?