The way I read the manual and understand Gerald is that it isn't safe any more than it is safe to play Russian roulette because you don't always get shot. As Gerald said, you just might get lucky and not blow anything... until you do.
On Thu, Mar 6, 2014 at 9:03 AM, Eric Palmer <e...@ericfpalmer.com> wrote: > If everything is driven form the same power source, even with voltage > dividers or regulators, can we assume that turning on all devices at the > same time, with one power switch, is safe or do we need to somehow put a > delay into powering on everything but the BBB board? > > Eric > > > On Thu, Mar 6, 2014 at 9:58 AM, Gerald Coley <ger...@beagleboard.org>wrote: > >> I put that in there for a reason. It may not happen all the time, but >> eventually you could blow up the processor. >> >> Gerald >> >> >> On Thu, Mar 6, 2014 at 8:56 AM, Matthew Witherwax <ablec...@gmail.com>wrote: >> >>> As part of the Control of Mobile Robotics class offered through Cousera, >>> the students are building robots based around the BeagleBone Black. The >>> robot has 5 infrared distance sensors and 2 reflectance sensors used for >>> odometry. These sensors are connected via voltage dividers to pins 33, 35, >>> 36, 37, 38, 39, and 49 of P9, and are powered from the same power supply >>> used to power the BeagleBone Black. The System Manual has a rather >>> explicit warning: >>> >>> NOTE: DO NOT APPLY VOLTAGE TO ANY I/O PIN WHEN POWER IS NOT SUPPLIED TO >>> THE BOARD. IT WILL DAMAGE THE PROCESSOR AND VOID THE WARRANTY. >>> NO PINS ARE TO BE DRIVEN UNTIL AFTER THE SYS_RESET LINE GOES HIGH. >>> >>> My concern is the current arrangement would allow the sensors to begin >>> driving the pins before the SYS_RESET line goes high; however, I am a >>> software guy just starting down the hardware path. Thus far many in the >>> class have been using the robot without issue. Is my concern invalid? >>> >>> Thank you for your time. >>> >>> -- >>> 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. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> -- >> 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. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > > > -- > Eric Palmer > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/_5Puwswy-RQ/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > -- 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. For more options, visit https://groups.google.com/groups/opt_out.
