No HDMI, parse-edid gives IO error

I’m trying to get BBB HDMI working, but not having much luck.

Set up:
BBB powered by ext 5V supply
serial console running into putty
BBB running 2013-05-20 image
Powered USB hub with keyboard and mouse
enet cable not connected
BBB not connected to PC via USB cable
micro HDMI to HDMI cable, hdmi to DVI adaptor, plugged into DVI input on Samsung 910T
Monitor is 1280x1024 native resolution

Power up BBB - all appears fine but no display on monitor
Monitor says no input signal, check cable

logged into the BBB to try to get EDID info - here is result:

Angstrom v2012.12 - Kernel 3.8.13

beaglebone login: root
Last login: Sat Jan 1 00:00:41 UTC 2000 on ttyO0
root@beaglebone:~# cd /sys/class/drm/card0/card0-HDMI-A-1/
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid edid
parse-edid: parse-edid version 2.0.0
parse-edid: IO error reading EDID
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# ls
device dpms edid enabled modes power status subsystem uevent
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# cat edid

What should I try next to gather diagnositc info?


Do you have everything plugged in before you put power to the BBB? If not make sure your cables are connected to the monitor and your BBB before you power on your BBB. Also make sure the monitor isn’t in sleep mode.


Yep, I’ve done that.
I tried all plugged in before BBB power up, monitor on.
I also tried the reverse: BBB up, then plug in hdmi - same results.

I did some more tests to rule out cable problems.

The video cable chain is:
BBB → micro hdmi to HDMI cable → HDMI to DVI adaptor - > monitor = fails to show video

I’ve verified the cable and adapter by swapping my phoen for the BBB
Phone → micro hdmi to HDMI cable → HDMI to DVI adaptor - > DVI monitor = works OK
Phone → micro hdmi to HDMI cable - > HMDI TV = works OK

This tells me the cable and hdmi to DVI pin conversion adaptor are OK, as are both monitors I have to test with.

Also retried the BBB on both the samsung monitor (DVI input) and a Viera TV (HDMI input) - both give same result of
IO error when trying to use parse-edid.

I think that leaves the BBB as the primary suspect…
At the moment I don;t have an idea for getting more info.


It may just be that your converter is drawing too much power or needs too much power to work correctly. We are currently testing some HDMI to VGA adapters to gather a list of working adapters and we ran into this problem. Does your DVI adapter require an external power source? For us, the adapters that required their own power source worked and the ones that didn’t have a power source didn’t work. It may sadly be that you do not have a compatible adaptor.


I think you are thinking of a HMDI to RGB converter. Those have to convert digital (HDMI) signals to analog signals (RGB) and they use active electronics to do it. In my situation there is no “converter” involved.

A HDMI to DVI adapter is a simple mechanical connector adapter between connectors where the pins are simple straight thru connections inside the adapter - so there are no digital to analog conversion electronics and thus no power draw involved.
So unless the BBB is unable to supply zero power, I suspect that is not the problem… :wink:


Hi All,
I’m thinking there is no BBB hardware problem here -
Over the weekend, I made a Ubuntu 13.04 boot SD (following Robert Nelsen’s fine instructions). I just used the default kernel cinfig settings for the BBB.
Put the ubuntu SD card in the BBB, booted, and guess what? Yep, the same BBB, same cable, same hdmi to DVI adapter and same monitor all just work under ubuntu. Clearly Ubuntu is talking to the monitor and getting good EDID info etc.

This little experiment rather makes it look like at least some of the BBB HDMI video issues and the inability to read EDID info from monitors are Angstrom specific problems.



would mind linking to Robert Nelsen’s “fine instructions”???


ubuntu demo images for testing: