Completely understood; however, assuming one could meet board area and timing constraints, it might be possible to wrap the processor with a circuit prophylactic, as it were...
I've also been part of several ARM-based core silicon projects, and it would have been possible for that (i.e. consistent pre-reset I/O state) to have been addressed at the chip level. Mike On Tuesday, September 8, 2015 at 5:56:32 AM UTC-6, Gerald wrote: > > I/O pin functionality is a function of the processor. Not the board. > > Gerald > > On Mon, Sep 7, 2015 at 10:05 PM, rattus <[email protected] <javascript:>> > wrote: > >> On Monday, September 7, 2015 at 6:52:12 PM UTC-6, Graham wrote: >>> >>> Well, by definition, the boot programming pins are going to have the >>> pull-ups / pull-downs, so you know what they are going to be doing, until >>> over-ridden. >>> >>> Most processors start up with the programmable pins as inputs, then move >>> to the configured state. >>> >> >> If it were so... but it seems with such an abundance of modes and pins, a >> number of the pins I am using are in a variety if input, output, hi-Z and >> I/O defaults at powerup, most often with pullup or pull-downs. The good >> news is, I've added enough gating and the additional fast-starting Vdd to >> avoid conflicts. SPI attached peripherals (powered early) all need commands >> shifted in to drive outputs, so that's safe too. >> >> Now for the *next* Beaglebone, innocuous I/Os would be a great feature... >> >> Anything else can be dangerous to the pins. But, as Charles says, RTFM. >>> >> >>> If you are concerned, use the bus-isolation /transmission-gate chips, >>> power them early, supply your own pull-ups/pull-downs, and switch the >>> connection on when SYS_RESETn goes high. Then you are unconditionally >>> safe, and in-control. >>> >>> --- Graham >>> >> >> Thanks, >> >> Mike >> > -- 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.
