should having the USB serial/UART adapter inserted prevent reflashing?

putting together another BBB and had popped on specialcomp's
mini-USB serial/UART adapter and when i went to reflash ... nothing.
tried again ... nothing. removed adapter ... no problem.

  should i have expected that? does it make any sense?

rday

I don’t have any idea. Never used it. Never seen a schematic. It does sound like it has issues. I suggest you contact Bill on this one.

Just my opinion, but I don’t see this as a desirable expectation.

Gerald

i'll test it again later, maybe it was just a fluke, but what i was
was, with the adapter inserted, when i plugged in power, i saw the
power LED go on and ... nothing. waited at least 10 seconds for
reflashing to start but it didn't.

  unplugged, replugged power (5V both times), again got power LED but
nothing else. unplugged, removed UART adapter, then reflashing kicked
off nicely.

  i'll test again later to see if it's reproducible.

rday

Sounds like the wrong polarity on the TX pin locking up the processor.

Gerald

just tried it again, it appears totally reproducible.

rday

That is always good.

Gerald

Robert,

i just tested with three different TTL Uart to USB adapters with the flash procedure with no issues.

Dave

i tested specifically with the adapter at specialcomp, you can see
on this page:

  https://specialcomp.com/beaglebone/

item [20411]. it's not a big deal since all it requires is to pop off
the adapter to reflash, but it has prevented reflashing for me 5/5
attempts. i can only report what i've observed.

rday

And what was Bill’s response? If you will notice, it isn’t on the list of USB to TTL adapters.

Gerald

Robert,

that appears to be a variation of the board that Sparkfun.com sells. i have not tested this one myself. i’ll get one ordered to review…

Dave

  i tested specifically with the adapter at specialcomp, you
can see on this page:

  BeagleBone Black Store

item [20411]. it's not a big deal since all it requires is to
pop off the adapter to reflash, but it has prevented
reflashing for me 5/5 attempts. i can only report what i've
observed.

Try using jumper wires to only connect rx/tx/gnd?

I haven't checked the BBB schematic, but I seem to recall that the
stock 6-pin FTDI connector provides 5V on one pin. I hope that does
something sensible. The other two pins are associated with flow
control.

I have reflashed my BBB with serial adapter attached just yesterday
and everything worked fine. I could log on and monitor reflashing
progress with top. I have a 6-pin FTDI cable from Adafruit:
http://www.adafruit.com/products/70
Try connecting only rx, tx and ground lines. It this won't help,
connect only ground line and see if reflashing works. You may have a
problem with no grounding or ground loop. You can also check the
potential difference between BBB ground and ground wire in the serial
cable.

j.

Only TX,RX, and ground are connected, so any other signals including the 5V should not be an issue. There is a pulldown on the RX line on the BBB. If the RX line is driven high by the adapter, then there could be issues…

Gerald

well, i'm just going to let this one go ... if anyone wants to
follow up and confirm this one way or the other, go for it.

rday

I will leave it Bill to talk about the products he sales and how they are supposed to work. I have zero information on this board other than a picture from his website.

Gerald