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DLPDLCR2000EVM: Beaglebone Black Wireless -- Cape ceases to function when plugged into BBB

Mark Hughes
Intellectual 350 points
Part Number: DLPDLCR2000EVM

Hello,

     I purchased a DLPDLCR2000EVM Cape (Cape) and a BeagleBoneBlack Wireless (BBBW).  Both new out of the box merchandise.  I am using a mean-well 40A 5V power supply with 5.5mm pigtails to provide power to the BBBW and the cape..

When the cape is disconnected from the BBBW, and connected to the power supply, the cape immediately springs to life and displays the splash screen (temp, security, whatnot).  While disconnected, the BBBW works as well.

But once connected, the cape shows no signs of life -- no LEDs light, no display is shown.  The BBBW still appears to function, and i2cdetect shows the memory locations 0x54-0x57 responding, but nothing else.

This has all the hallmarks of a power problem, however I am powering the BBBW and the cape from wires connected to the same pins on the same supply -- so they should have identical ground references.  Additionally, I've tried multiple pigtails and multiple configurations to no avail.  They work independently, but not together.

What's going on, and what is the best place to start troubleshooting?

Thanks,

Mark

Writer/Technical Editor

AllAboutCircuits.com

  • 0
    TI__Mastermind 28005 points
    Mark,

    In this case, your problem is most likely the cape overlay (or lack thereof) on the BBBW. You need to ensure you either download a distro of Debian that has the cape overlay loaded by default, or load the cape overlay yourself. You can download the cape overlay driver source to compile yourself here:
    e2e.ti.com/.../663939

    Let me know if you need assistance with this process. I hope that helps.

    Best Regards,
    Philippe Dollo
  • 0 in reply to Philippe Dollo
    Intellectual 350 points

    Hi Philippe,

         Thanks for the reply.  Unfortunately, that did not resolve the issue.  However, I have made some progress.

    There is a pin on your cape (P2_15) that corresponds to GPIO_48 (P9_15) on the BBBW.  It's labeled "PROJ_ON_EXT" -- the default state is logic low.

    I repurposed one of the blinky-led demo scripts to force the pin-state to logic-high and the cape suddenly lit up.

    It seems the proper solution would be to learn how to properly change the default state of that pin.

    I've never used a beaglebone board before, so this is all new to me.  (I have used  Debian-based Linux distros, as well as RaspberryPis, so it's not completely foreign).

    Do you happen to know the recommended way to set that pin high at boot?

    Thanks,

    Mark

  • 0 in reply to Mark Hughes
    TI__Mastermind 28005 points
    Mark,

    There are two parts to this question. First is how to set GPIO pins on the BeagleBone and second is how to execute commands on boot.

    1. To configure GPIO pins on your system, execute commands as detailed in the "Configuring Accessible GPIO Pins" section of this blog:
    vadl.github.io/.../setting-up-bbb-gpio

    2. There are a number of way to execute commands on boot. I recommend either setting up a bash script to execute on boot. One way to do this is setting it up as a service, which is discussed here:
    stackoverflow.com/.../executing-a-script-on-startup-using-beaglebone-black

    If you have further questions about the Debian side in particular, I recommend you also ask on the BeagleBoard community forums (http://beagleboard.org/)

    I hope this helps.

    Best Regards,
    Philippe Dollo