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/jkuahbpu3i94tkjuam7ifbc77hpue29nn4%404ax.com. For more options, visit https://groups.google.com/d/optout.
