Hi all, I work with a BBB for a project where the I need to record data from an Ethernet connection. The OS sits on the eMMC while the data goes to the µSD card. To boot from the eMMC while there is a µSD in the slot, I followed the instructions on this post <https://groups.google.com/forum/#!topic/beagleboard/MKApMsH3Q7M> (formatted µSD card with 2 partitions, put a uEnv.txt file on the first one) and got the board booting on the eMMC. Yay. Since the power is intermittent, the BBB is equipped with a battery that lets it turn itself off (in case power is gone). When power is back on, the board boots again. So the BBB needs to be able to boot autonomously when there is power on USB and to turn itself off afterwards. I did the shutdown with a script and this part works fine. (of course there is always the case where the power is back on just when the BBB is shutting down, but I guess I can't do anything about it).
What does not work is that I sometimes find the board in a strange state, where only the power LED is lit while the user LEDs are off. It seems that I am encountering the issue discussed in this thread <https://groups.google.com/forum/#!topic/beagleboard/aXv6An1xfqI>, where the RX pin of the FTDI receives fake data, which stops U-Boot and prevents the board from booting normally. After reading the whole thread, two solutions seem to exist: - hardware fix: use a 10k pull-up resistor between the RX pin and the 3.3V - software fix: reconfigure U-Boot to look for a string (instead of just any data) to enter into its communication mode I have implemented the hardware fix and am currently testing it (booting every five minutes). However, I would rather use the software fix to U-Boot as it does not require any modification to the hardware. So I followed the link on this post <https://groups.google.com/d/msg/beagleboard/aXv6An1xfqI/2_tLa7oWQBIJ> (to eewiki.net <http://eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-Bootloader:U-Boot>) to build U-Boot from the official git repository and created MLO and u-boot.img files (that I can patch with the few lines on the post, but I haven't done this yet). My problem is: those instructions are designed to make the BBB boot from the µSD card. Actually, it even requires to remove the OS from the eMMC (or to remove the MLO file so that U-Boot doesn't see it), or to replace the uEnv.txt by the one there <http://eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-DealingwitholdBootloaderineMMC>, otherwise it is stuck. My files work, as I can boot from a µSD card containing Linux. However, when I tried replacing the MLO and u-boot.img files on the eMMC (you can't blame me for trying, but I agree that it was a long shot), it of course hanged. I am a total newbie in the U-Boot world and I find it complicated since I don't even know where to start. What I would like is just to be able to modify the official version of U-Boot to boot from the eMMC. Ideally, I would also remove the need to create two partitions and to add a uEnv.txt on the µSD card, but that is not a requirement. Also, it would teach me how all of this works and give me a little more control over this part of the project! If any of you has either a solution or a forum thread which I have not found or even a *simple* "how to use U-Boot" tutorial that does not involve going through hundreds of pages of technicalities (that, I have found), I would be really happy! Thank you all in advance! Regards, Alexandre -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
