FCDEV3B hardware bug: sleep mode self-reboot

Das Signal das.signal at freecalypso.org
Sat Jul 29 11:33:17 UTC 2017


Hi Mychaela,

Thank you for the detailed indications. I have first recompiled magnetite
in the l1reconst configuration and flashed it. I can confirm that issuing
the AT+CFUN=1 command through fc-shell does cause a reboot of the board
(and does not cause one with AT%SLEEP=2 issued before).

I had no problem identifying the three caps, and indeed the voltage is
at 1.5V which is expected. In the three cases, I have issued the AT+CFUN
command while observing the output on the scope. There was no voltage drop,
however there was some slight "noise", which is to say the voltage varied
a little bit around 1.5V (at most +/- 0.1V). However this could be due to
the power draw when the board was rebooting, as this noise appears much
after the AT command. Please have a look at the oscilloscope screenshot
that illustrates the situation:
https://www.freecalypso.org/members/ds/NewFile1.png

I've noted that the radio part of the board does not seems turned on
until after AT+COPS=0 is issued; hence the possibility that the RF part
is not (at least directly) responsible for this situation (RF TX would
likely be the most power hungry part of the board).

--DS


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