GPIO default pin level

[Mike Brandon]

I have been spending some time trying to understand device tree overlays. Currently my uEnv.txt is configured so that:

##BeagleBone Black: HDMI (Audio/Video) disabled:

dtb=am335x-boneblack-emmc-overlay.dtb

cat /sys/devices/platform/bone_capemgr/slots

 0: PF----  -1

 1: PF----  -1

 2: PF----  -1

 3: PF----  -1

 4: P-O-L-   0 Override Board Name,00A0,Override Manuf,univ-emmc

I would like to keep the GPIOs that default as PIN_OUTPUT_PULLUP from doing so, and would prefer them to pulldown.

What is the best way to go about doing that?

[Mike Brandon]

I have made progress on this and have a .dtbo that I can load manually and set all of my gpio in the desired state I am looking for.

My issue now is getting this overlay to load on boot. Here is my uEnv.txt:

uname_r=4.4.113-ti-r149

enable_uboot_overlays=1

dtb_overlay=/lib/firmware/univ-emmc-smb-00A0.dtbo

disable_uboot_overlay_video=1

disable_uboot_overlay_audio=1

disable_uboot_overlay_wireless=1

cmdline=coherent_pool=1M net.ifnames=0 quiet cape_universal=enable

I can manually load the overlay by:

root@beaglebone:/lib/firmware# echo univ-emmc-smb > $SLOTS

Bootloader version:

bootloader:[microSD-(push-button)]:[/dev/mmcblk0]:[U-Boot 2018.09-00002-gd5b4c4b656]:[location: dd MBR]

What am I missing?

[Mike Brandon]

I resolved this by disabling the old version of the u-boot bootloader on the eMMC: (a step suggested in anothe rpost I had here https://forums.adafruit.com/viewtopic.php?f=49&t=142107)

sudo dd if=/dev/zero of=/dev/mmcblk1 bs=1M count=10

On Friday, November 23, 2018 at 8:22:48 PM UTC-5, Mike Brandon wrote: