That is a long email. Send me a direct email, and at some point we can have a discussion.
Gerald On Mon, Jul 20, 2015 at 6:36 PM, Alan Rosenbloom <rosenbloo...@gmail.com> wrote: > Gerald: I am super impressed that you would offer your valuable time to > help with not much in return than thanks. > > Background: I’m developing a complicated prototype and I am new to > embedded systems. I was fairly frustrated that I could not “just hook > things up” and have them at least not destroy the BBB while testing. I am > beginning to understand that, like any device, more capability comes with > more complexity and vulnerabilities. I still see the BBB as an amazing > opportunity for inventors overall and realize that I need to learn more to > use it properly. > > I cannot point to one circuit that caused the damage to > the BBBs because I am trying different arrangements to integrate multiple > devices. However, if you could answer some basic questions on design > strategy, that could help. > > > *Here’s what I need to accomplish:* > > I need to power 4 accessories: (1) a small stepper motor through the > Pololu DRV8834 driver board. It consumes about 200 – 300 mA at 5 volts, (2) > an IC chip via pulse wave modulation – it requires about 620mA at 1.55V, (3) > a small DC motor which consumes about 40 mA at 3V (either by PWM and a > relay or straight from a 3.3 V source) and (4) a small cooling fan – > consumes about 120 mA at 5 V. > > I need to control turning all these on and off by a clock function. > > I need to read a GVS digital sensor: consumes less than 10 mA at 5 V. > > I need to read a GVS analog input: 5V input, output < 1 volt. > > I need to read DC voltages (analog): (1) on a pin on the DRV8834 driver > board (0-1 volt range), (2) on a sensor with special input requirements – > it needs both (+) 5 volts AND (-) 5 volts inputs to power it. The (-) > voltage is derived from (+) 5 V using this inverter ICL7660A, which I have > found to be about 91% efficient at converting DC (+) to DC(-) for this > application. Sensor output max about 1.2 volts. > > Finally, I need to add and read a real time clock (RTC) such as the > Chronodot (Adafruit) – requires I2C bus SDA, and SCL, as well as GND and > (+) 5V. > > > *What do you think of these strategies:* > > (1) Use the BBB-GVS board (http://beagleboard.org/project/BBB-GVS/). > This board appears to provide a layer of protection from the sensor voltage > inputs and power outputs for the BBB. The problem is they may not be a > reliable supplier and I cannot tell if this board will accomplish all these > tasks. > > (2) Use the BBB only for logic and supply all the power from an > independent (probably 5V cell phone charger power pack) source with voltage > regulator, using PWM and relays to regulate the voltages lower than 5 V and > relays to control intermittent power needs. Would this be safer for the BBB > i.e. not using power directly off the BBB while trying to read sensor > output at the same time? It seems dangerous to me tying all the grounds > together (analog, digital and power) that would be required to get both > power out of the BBB and signal into it. > > (3) Power the BBB via a 3.7 volt backup battery through TP5 and TP8 to > prevent abrupt cessation of power should a system failure occur. Seems like > it would be possible to write code to give the “sudo shutdown –h now” > command when the power went down. This would allow the PMIC time to do an > orderly shutdown. > > > > I suspect that the sensors may be putting voltages on the BBB pins before > they are powered up as part of the problem, but I am not sure how to > prevent this. Is there a way to power up the sensors after the BBB has > properly booted and to shut them down before the PMIC does its shutdown > sequence? Any other external wiring or devices that could help safeguard > the BBB? Any advice you can offer on any of this or other ways to protect > the BBB would be appreciated. > > On Sat, Jul 18, 2015 at 8:31 PM, Gerald Coley <ger...@beagleboard.org> > wrote: > >> If you do not use it properly, it will be damaged. That applies to every >> electronic circuit ever designed. I would have stopped using the circuitry >> after the second try. >> >> I would be happy to look at your circuit and see if I can identify what >> the issue might be. >> >> Gerald >> >> >> On Fri, Jul 17, 2015 at 10:27 PM, <rosenbloo...@gmail.com> wrote: >> >>> I now have 4 damaged or dead BBBs. On this last board (Element 14), I >>> had only a stepper motor driver board connected (Pololu DRV8834), and >>> nothing else. The DRV8834 was initially drawing power from the VDD5v on the >>> BBB. The BBB "blacked out" twice while nothing was happening and while >>> connected to both a 5V regulated power supply (Adafruit) and USB power. I >>> was worried that the DRV8834 was drawing too much power (although I have >>> found it uses < 200 mA @ 5V), so I used a separate power supply for the >>> DRB8834. Only the logic of the DRV8834 was hooked up to the BBB - nothing >>> that would supply power and no analog inputs. The third blackout also >>> occurred without an obvious precipitant - again with both power sources >>> connected (USB and barrel plug). Now the power LED flashes briefly when >>> either USB or barrel plug power (Adafruit power source for BBB) is >>> connected to the BBB. It will not sustain the power button nor boot up. >>> >>> This seems to be a repetitive theme on this forum. I am losing faith in >>> the BBB ever functioning in a real world environment if it is this fragile. >>> Is there any way to protect the BBB processor (or whatever is blowing) with >>> external circuitry or power? >>> >>> Appreciate any help. I'm now out over $200 with these boards and I >>> cannot identify anything that should be damaging them. Considering changing >>> to another system at this point. Although I am impressed with the >>> capability of the BBB, I would not call it a robust system. >>> >>> Help! >>> >>> >>> >>> On Thursday, June 11, 2015 at 9:08:39 PM UTC-4, Gerald wrote: >>>> >>>> The flashing LED indicates excess current is being drawn by the >>>> processor. This can be related to damaged I/O pins or power supplies that >>>> are not well regulated.. >>>> >>>> Gerald >>>> >>>> >>>> On Thu, Jun 11, 2015 at 4:38 PM, <ahad...@gmail.com> wrote: >>>> >>>>> I have the same issue, already 3 boards has died. >>>>> any solution, i tried to use optoisolator/pwm and noting. the BBB is a >>>>> bad board. >>>>> >>>>> >>>>> >>>>> Le mercredi 25 février 2015 18:03:24 UTC+1, mdtsa...@gmail.com a >>>>> écrit : >>>>>> >>>>>> Identical problem this morning: BBB boots fine when powered by USB, >>>>>> but not when powered by a 2.0 mA rated 5.0 V DC power supply (nicked from >>>>>> some other device). BBB power LED blinks continuously. This power >>>>>> supply >>>>>> has worked with this BBB in the past. >>>>>> >>>>>> Mike. >>>>>> >>>>>> On Friday, January 23, 2015 at 8:44:59 PM UTC-8, 1127...@gmail.com >>>>>> wrote: >>>>>>> >>>>>>> I had a similar problem- my power LED would just continue blinking >>>>>>> when connected to a 5V power source. This meant there was something >>>>>>> wrong. >>>>>>> First, I checked if my BBB was still alive. To find that, I connected my >>>>>>> board to a computer via USB. Surprisingly, this time power LED turned >>>>>>> on >>>>>>> normally. Then to make sure that everything was properly, I ran some >>>>>>> program as given in the BB website >>>>>>> http://beagleboard.org/getting-started. I was happy to see, the >>>>>>> programs on the website worked just fine on my board. Thus, I was able >>>>>>> to >>>>>>> conclude that strangely, my BBB board didn't like 5V external power >>>>>>> source! >>>>>>> >>>>>>> On Friday, November 22, 2013 at 6:41:41 AM UTC-8, Bert Lindner wrote: >>>>>>>> >>>>>>>> >>>>>>>> Just had a 5V powered Beaglebone Black seemingly die on me. First >>>>>>>> the power led kept blinking, then after removing the (BB Toys CAN) >>>>>>>> cape the >>>>>>>> power led would flash just once after applying power. Looking back in >>>>>>>> previous threads this seemed to mean I killed the board somehow; there >>>>>>>> was >>>>>>>> also a GPS module attached to one of the UARTs and a probably power >>>>>>>> hungry >>>>>>>> USB wlan stick that I'm trying to get to work, so a power hungry setup. >>>>>>>> >>>>>>>> I was ready to declare it dead, it remained just flashing once >>>>>>>> after repeatedly unplugging and reattaching the power supply. >>>>>>>> >>>>>>>> However I noticed the single power led flash would also happen if I >>>>>>>> pressed the power button (leaving the 5V plug in). Doing that >>>>>>>> repeatedly >>>>>>>> seems to have revived the board, will see if new problems occur. For >>>>>>>> now it >>>>>>>> behaves normally. >>>>>>>> >>>>>>>> Is this expected behaviour? >>>>>>>> >>>>>>>> Best, >>>>>>>> >>>>>>>> -Bert >>>>>>>> >>>>>>>> -- >>>>> 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...@googlegroups.com. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>>> >>>> -- >>>> Gerald >>>> >>>> ger...@beagleboard.org >>>> http://beagleboard.org/ >>>> >>> -- >>> 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/d/optout. >>> >> >> >> >> -- >> Gerald >> >> ger...@beagleboard.org >> http://beagleboard.org/ >> >> -- >> 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/jBFshjlPeHI/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/d/optout. >> > > -- > 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/d/optout. > -- Gerald ger...@beagleboard.org http://beagleboard.org/ -- 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/d/optout.
