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 <[email protected]>
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, <[email protected]> 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, <[email protected]> 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, [email protected] 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, [email protected]
>>>>> 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
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>>>>
>>>
>>>
>>>
>>> --
>>> Gerald
>>>
>>> [email protected]
>>> http://beagleboard.org/
>>>
>> --
>> For more options, visit http://beagleboard.org/discuss
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>
>
>
> --
> Gerald
>
> [email protected]
> http://beagleboard.org/
>
> --
> For more options, visit http://beagleboard.org/discuss
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