Mike: In the case of those boot programming pins, the definition of "not-driven" includes NOT LOADING the pins.
If you are using CMOS inputs on I.C.s that are already powered up, then O.K. If the the "inputs" that you are hanging on the boot pins are ICs that are not powered up yet (because you used the VDD_3V3B rail to power them), then the ESD diodes are putting a short to ground on the boot pins. If the "inputs" that you are hanging on the boot pins are bipolar transistors, with pull down resistors in the circuit, you could be over-riding the boot instruction "highs" and turning them into lows. You have been warned. :-) --- Graham == On Saturday, September 5, 2015 at 10:37:56 AM UTC-5, rattus wrote: > > Thanks guys. I will not be driving anything at boot, as all the cape pins > are initially configured as inputs. > > Surprisingly, I did read sections 6.7 and 8.3. It would have been nice if > the P8 pins had been referenced in those diagrams, rather than having to > trace the schematics. > > mike > > On Saturday, September 5, 2015 at 7:44:02 AM UTC-6, Charles Steinkuehler > wrote: >> >> On 9/4/2015 10:35 PM, rattus wrote: >> > Just want to verify something... I an *not* using HDMI, McASP, gpmc, >> UARTs, >> > the ADC or I2Cs. I am using the EMMC. Just SPI0 and a bunch of GPIOs. >> > >> > Can I assume that any P8/P9 pins labeled as GPIO in some mode, and >> *not* >> > labeled "allocated for EMMC2"* on Derek Molloy's helpful P8/9 charts is >> > available for GPIO purposes? >> > >> > Are there any other preallocated P8/9 GPIO-potential pins I need to >> watch >> > out for? Just checking before I commit the cape from Hell to fab. >> >> In addition to not driving the boot pins while reset is asserted >> (unless you're intentionally trying to change the boot mode), you also >> need to watch out for the cape EEPROM I2C lines (P9, pins 19 and 20). >> These pins will be in I2C mode at boot-up, and will be twiddled by >> the cape manager as it looks for any connected capes. >> >> -- >> Charles Steinkuehler >> [email protected] >> > -- 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.
