FCDEV3B bring-up status

Mychaela Falconia mychaela.falconia at gmail.com
Sun Apr 9 07:59:09 UTC 2017

Hello again everyone,

Just to assure myself that the RF tract on our FCDEV3B is fine in
hardware terms and that our only problem in this regard is the lack of
VCXO calibration, I have run OsmocomBB's full mobile app with their
layer1 running on our FCDEV3B, with a real SIM in the SIM socket on
our board, and it works: I was able to connect to my local GSM network
(Operator 310260), and send and receive SMS successfully.  I have also
succeeded in dialing and connecting a voice call, although I couldn't
test the voice path as the off-board loudspeaker and microphone have
not been added yet.

When it comes to audio, I designed the FCDEV3B with the intent of being
able to make test calls from the lab bench without needing anything
except the board itself, and for this purpose there is a loudspeaker
driver circuit and a microphone input circuit on the board.  However,
the actual loudspeaker and microphone themselves aren't on the board,
instead there are headers meant for connecting them.  At some point I
will need to acquire some loudspeaker and microphone parts, wire them
up to the headers and test these on-board audio circuits, but right
now there are higher priorities.

For me the bring-up priorities going forward are as follows:

1. Get to the bottom of the flash boot mystery.  We are not OsmocomBB
and our firmware is meant to run from flash, hence the flash boot
problem needs to be solved before I will feel comfortable taking on
other major challenges like calibration.  In order to gather more
insight into this flash boot mystery, I need to connect JTAG to our
board, and I am currently missing the necessary jumper wires.  I need
jumper wires like these:


I already placed the order for the above back on Wednesday, but the
seller warns that they may take a month to arrive.  In the next few
days I will see if I can procure similar jumper wires more locally.

2. Climb the calibration learning curve and get our FCDEV3B's VCXO
calibrated on the CMU200 so we can bring up the GSM radio using our
preferred firmware, rather than OsmocomBB.

Hasta la Victoria, Siempre,
Mychaela aka The Mother

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