Thanks! It never would have occurred to me that a resistive load in this context is a "driver". Lesson learned!
Greg On Monday, April 18, 2016 at 8:26:47 PM UTC-4, Harvey White wrote: > > On Mon, 18 Apr 2016 17:12:37 -0700 (PDT), you wrote: > > >I'm trouble shooting a problem on a simple cape for a BeagleBone Black. > > > >I have a bipolar switch for an LED, very similar to that used for the > "User > >LEDS". > >So I have added an approximately 10Kohm load to one of the "boot pins", > >which > >in header lingo is P8_44. > > > >P8_44 is also one of the "boot" pins. I'm interesting in using the PRU > >connection mode of this pin. > > > >The System Reference Manuals says the boot pins must not be *driven* > prior > >to coming out of reset (SYS_RESET goes high). > > > >So maybe my understanding of the term "driven" in this context is > >incorrect, and it could also be interpreted as "loading", > >as in excessive resistive loading? > > Driven in this case (and lots of others) means a signal connected to > that pin. > > A resistor going to VCC or ground does indeed "drive" that signal. > > BOOT pins must completely float until the boot process is done, *then* > you can do something with them. > > A good idea is to avoid boot pins > Another good idea is to use tri-state drivers on those pins, and turn > them on ONLY when the boot process is done. > > There are a number of threads discussing this. > > However, nobody has specifically said that resistors effectively drive > boot pins. They do. > > Harvey > > > > > >I tried an experiment on both BBB and BBG with a 10kohm resistor to > ground > >on P8_44. Both refused to boot up and run. > >So is it a requirement to keep resistive loads off this pin during the > boot > >process? > > > >Regards, > >Greg > > -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/63732160-6bec-4da7-8c65-2a38d1451d0a%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
