We have no instructions on how to break the board.The TPS65217C is designed to power the board from either of these sources, whichever one come first. If 5V is connected it switches to 5VDC when connected.
One way to do what you want is to remove the power connection in your cable, cut the wire. However, if you do that, the processor will not recognize the USB as being connected and will not enumerate. On power off, the TPS65217C clears all the registers, so any registers that are set, will be reset on power up. Gerald On Fri, Sep 27, 2013 at 10:14 AM, TB <[email protected]> wrote: > > Hi, > > I need to disable the BBB from booting when usb is connected to the PC. I > have an external supply that powers the BBB as well as other things. I > would like the configuration such that even if a user connects to the BBB > via USB it will not boot until the 5V main power supply is turned on. > > Looking at the schematics and SRM I know that the TPS65217C senses the USB > 5V on its pin 12 and that there is some registers that control how > the TPS65217C responds to different signals and these registers are written > to via I2C. i just don't know how to do that. The following thread talks > about some commands that can be added to uEnv.txt to write to the > TPS65217C. I just wish there was more detail on how to do this. > > > https://groups.google.com/forum/#!searchin/beagleboard/USB$20power/beagleboard/yNjXHmb1WnA/nlBoqnetbgcJ > > Are there easy instructions to modify the registers on the TPS65217C to > disable USB powerup? > > hardware: BBB A5C > OS: R. Nelsons' Ubuntu 13.04 (works great!) > > Thanks > > T. > > -- > 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/groups/opt_out. > -- 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/groups/opt_out.
