Hello, I just finished reading a lot of posts on the topic of starting up the BBB and various issues that folks have had. I didn't see anything that reflected my situation, so I'm going to reach out in hopes that someone in the group can cast some light on this.
I have a BBB with a custom Cape. The Cape is designed to interface the BBB to a cap-touch color screen. The Cape contains the backlight power supply for the display and the obligatory EEPROM for ID, addressing pins, etc. Very similar to the BB-CAPE-DISP-CT43 <http://tinyurl.com/ybj9s68m> available for purchase. What is different in my case is that I'm supplying power to the Cape (5V). The power then goes to the Cape connector on P9, pins 5 & 6. This would be equivalent to supplying power to the BBB via the barrel connector. The BBB is internally booting (no SD, etc) with custom code. I have written the shipping code image into the board and I get the same results. I've made several dozen of these assemblies now, and so far I have two that exhibit this odd behavior. The symptom: The BBB will attempt to start, will shut down, and will try to start once more at a rate of about once per second. Sometimes this only happens a couple of times, other times I simply give up after 60 of these failed boot cycles. There is no consistency to the number of tries a board will go through. I'm using a very robust power supply that meets or exceeds the PMIC slew rate requirements. The supply is capable of supplying 12A @ 5VDC. When the BBB is attempting to boot, the blue LED adjacent to the barrel connector (commonly referred to as the Power LED) will flash briefly. There are occasions when a 'bad' assembly will boot without issue, but most frequently it comes up in this flashing state. I've checked for the usual suspects, bad solder joints, interconnects, etc, without finding anything. I know that my inrush current is on the order of 1.7 to 1.8 A at the initial startup, but that drops off significantly after the caps are charged up. Has anyone out there experienced this pulsing behavior and found a root cause and possibly a fix? One thought that I had was to monitor the bebug port (X1), but is there even enough up time to have this be useful? Thank you to everyone in advance for your insight. -- 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/8f22dd81-53cd-4a1d-b619-7b382fe9ee92%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
