Perhaps. But how it is connected with the recording in the flash memory. 
eMMC powered from different supply VDD_3V3B. According to documentation it 
takes about 50mA in write mode. So why VDD_1V8 drops down ? Bad 5V power 
from USB ? I will examine this issue. But in all other cases BBB works 
well. I have to find a workarownd.
Externally it looks like some exception or power fail after some time of 
extensive write to eMMC. I should kill some more BBB to find an answer

вторник, 11 октября 2016 г., 22:13:22 UTC+3 пользователь john3909 написал:
>
> If the BBB oscillator is not running, then I suspect the processor is bad. 
> If you have two boards with the same issue, then I suspect the power supply 
> you are using is bad. One of the big issues with the BBB is it doesn’t like 
> to power down. Look at sheet 2 of the OSD335x schematics
>
>
> http://octavosystems.com/octavosystems.com/wp-content/uploads/2016/05/OSD3358-SBC-Referece-Design.pdf
>
> You will see some protection circuitry at the bottom center of the sheet. 
> This ensures the voltage difference between the 3v3 and 1v8 is never 
> greater than 2V. The BBB does not have any such circuitry so when the 5V 
> drops quickly, it is possible for the 1v8 to drop quicker than the 3v3 and 
> hence killing the processor. This happened to me and I had to replace the 
> processor.
>
> The Beagleboard-x15 does have the same protection circuitry 
> (BeagleBoard-X15_RevA2.pdf sheet 4). 
>  
> Regards,
> John
>
>
>
>
> On Oct 11, 2016, at 7:05 AM, Николай Курочкин <[email protected] 
> <javascript:>> wrote:
>
> Two BeagleBone black boards with 1GHZ processors do not make boot sequece 
> after some unsucceseful attemts to format eMMC.
> It looks like they do not make PORz sequence. Both ocillators inacvtive. 
> NRESET_INOUT is low. PORZn input high. All power voltages are OK.
> I use simple code wich make BBB to act as USB flash drive to monitor eMMC 
> with my PC. Code based on TI usb_dev_msc example in StarterWare.
> It begin happens only with new boards. Old revision boards works OK.
> Any body can help ?
> I going to use JTAG to debug this processors but not shure that JTAG will 
> work in this case.
>
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