Platform forum

GPIO not pulled up in openrex

shafy.s , 06-07-2017, 12:09 PM

We are using gpios in the openrex board to give inputs to a Qt based GUI application using buttons. From the Qt application, the pins are exported as gpio's with direction as inputs in /sys/class/gpio/
The pins are high and a button press will pull it down detecting it a press.

This is working perfectly in the initial set of openrex boards that we purchased.

But in a later set of boards purchased(same part number with imx6 quad), the pins 19,21 and 23 in the J2 header are not high by default. This causes the button press detection to fail.
These pins are the CSPI1 MOSI, MISO and clk pins
We are using the same sd card with the same kernel, dtb and Qt application to test. The SPI1 is disabled in the dts file.

There are some differences in the u-boot settings between these boards. eg: in the first board it is uboot is looking for the dtb file imx6q-openrex.dtb, but in the second board it is looking for imx6-openrexmax.dtb. Some other settings are also different by default.

Can someone provide some insight to fix this issue ? is this something related the any settings in u-boot ? The only software thing different while testing these boards are the u-boot and
the env settings. Or can this be due to any difference in the boot rom ?

robertferanec , 06-09-2017, 02:14 PM
Interesting. The first board were probably shipped with our (FEDEVEL Academy) software and later VOIPAC created their own software - so there may be differences. Double check if internal pull ups / downs are setup inside the CPU. You can set them up in Uboot or in Kernel. Let me know if that helped.
ranaya , 07-26-2017, 10:04 AM
Hi @shafy.s ,

The boards manufactured by VOIPAC has the default dtb name to imx6q-openrex.dtb in u-boot. I think you can simply replace the u-boot env variable name to input the dtb you desire. Since your application runs in kernel level I believe the correct dtb settings is the only thing you require.

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