Tricking the BeagleBone into outputting video

[FlorianH] wanted to get video out working with his BeagleBone but he just couldn’t figure out how to make the kernel play ball. Then a bit of inspiration struck. He knew that if you plug in the official DVI cape (that’s the BeagleBone word for what you may know as a shield) the kernel automatically starts pumping out the signals he needs. So he figured out a way to spoof the cape and output video.

At boot time the kernel polls the I2C bus to see what’s connected. The DVI cape has an EEPROM which identifies it. Since the data from the EEPROM is available for download [FlorianH] grabbed the data he needed, then used an ATmega32 to stand in for the memory chip. When he got the chip talking to the BeagleBone he was able to detect the video sync signals on his scope and he knew he was in business.

Look closely at the breadboard on the right. We love that SIL breakout board for the ATmega32. Very prototype friendly!

Comments

  1. barryronaldo says:

    He he nice job FlorianH on tricking the chip into doing its job :) My type of hack :) Keep up the good work and good ideas.

  2. Anka06 says:

    Great idea!

  3. chango says:

    I’m guessing the DVI cape has buffers so that it can be used in tandem with another video output cape like the VGA. Otherwise it seems like a waste.

  4. cde says:

    Video output is hardcoded as 1024*768 according to the DVI-D Cape pdf. For changing the way it works look at http://arago-project.org/git/projects/?p=u-boot-am33x.git;a=blob;f=board/ti/am335x/mux.c and http://arago-project.org/git/projects/?p=u-boot-am33x.git;a=blob;f=board/ti/am335x/evm.c#l699

    [u-boot-am33x.git] / board / ti / am335x / mux.c and evm.c

  5. Travis Estep says:

    Is there any possible way we could get the schematic for this hack?

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