On 17/12/17 00:34, Graham wrote: > An FTDI 3.3 Volt USB to UART0 connection will not blowup or hurt anything. > You an hook it up and leave it hooked up, and not have to worry about > damaging the Pocket Beagle, > A 10K pullup to +3.3 V is also OK, but not actually required for the > FTDI cable to work. > > Something like the TTL-232R-3V3-WE for wire pigtails. > > The damage warning is for things that will try to drive pins with > currents high enough to damage semiconductor circuits and/or ESD > protection circuits. > Or, in the case of the boot pins, something that will over-ride a 100K > resistor.
Ahh okay… yeah I used UART here as it's an example of something that would be generally wired up continuously and has the property of presenting a voltage when idle using push-pull logic. I'd likely use the MAX232 for a console port. By the sounds of things, the problem is more down to inrush current than voltage alone, and clearly the AM3358 doesn't have its pins in high-impedance mode at boot-up or else it'd be impossible to achieve those current levels. 3v3 in series with a megohm or more is never going to produce more than 3µ3A, and GPIOs in "input" mode often have a resistance in that ballpark. A GPIO driven as a low output however, could get nasty. The plan was to have a series resistor, so this should be sufficient to prevent catastrophe. -- Stuart Longland (aka Redhatter, VK4MSL) I haven't lost my mind... ...it's backed up on a tape somewhere. -- 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/61a7950d-69e7-5383-2bd0-aa1e37d582f1%40longlandclan.id.au. For more options, visit https://groups.google.com/d/optout.
