All your programmable I/O pins are going to startup in tristate mode. That means you can just add a weak pullup or pulldown resistor (EG. 10K) to each pin’s circuit to make your external devices behave properly until your software programs the pins.
From: [email protected] Sent: Monday, April 14, 2014 8:09 AM To: [email protected] Subject: Re: [beagleboard] Setting I/O's Dear Gerald, Isn't it possible to set the IO's in the U-boot? before the kernel is started. This would be fast enough. Regards, Maarten Op maandag 14 april 2014 16:40:16 UTC+2 schreef Gerald: Read the datasheet for the default state of each pin on power up. http://www.ti.com/product/am3358 These cannot be changed. Once the SW is loaded, it can set the pins to whatever function it supports. Gerald On Mon, Apr 14, 2014 at 9:37 AM, <[email protected]> wrote: Dear Reader, I have a question about the following problem. On the PCB I designed I use the BBB for setting some pumps and valves. When the system starts up the first seconds the IO pins are not logic 1 or 0. Is it possible to set the GPIO's in U-boot before starting up the kernel and how can I do this? Thanks, Maarten -- 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. -- 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. -- 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.
