FreeCalypso update: progress with DSP patches and voice calls

Mychaela Falconia falcon at ivan.Harhan.ORG
Wed Apr 6 18:25:24 CET 2016

Hi DS,

> I'm currently trying voice calls with leo2moko-debug, but this time with
> the trace output through the jack and a CP210x cable. The issue I'm seeing
> is that it's not possible to assert whether the audio is ok since it
> appears what I'm hearing is the UART output converted to an analog signal.
> Perhaps there is a trick that would allow having both the UART output
> and analog audio separate? I tried switching in the qtmoko GUI to
> the speaker but again the result was not acceptable.

In hardware terms, it *is* possible to have GSM voice call audio and
the trace serial channel enabled at the same time on the GTA02, but
the destination for the audio *must* be the earpiece speaker and not
the loudspeaker, and certainly not the headset jack.

I don't know how to do it with QtMoko GUI enabled, but if you would be
willing to disable this QtMoko GUI and work from the command line,
here is the recipe:

1. Stop QtMoko software:

/etc/init.d/qtmoko-neo stop

2. Find where the ALSA scenario files live:

find / -name gsmheadset.state -print

3. Once you find where the gsmheadset.state ALSA scenario lives,
   load it:

alsactl -f /path/to/gsmheadset.state restore

This ALSA scenario directs the Calypso GSM audio to the earpiece
speaker where it won't conflict with the headset jack being reused for
the debug serial channel, but you will have to hold the device up to
your ear in order to be able to hear it.  The requirement of holding
the device up to one's ear translates into the requirement for a
serial cable that is reliable enough and won't break the connection
when the device is lifted up from the table - I had this problem with
the Sysmocom CP2102 cable I got from DS, but the new official
FreeCalypso serial cables made by UberWaves are much better in this
regard. :-)

4. Enable the headset jack serial channel and power-cycle the modem:

echo 1 > /sys/bus/platform/devices/gta02-pm-gsm.0/download
echo 0 > /sys/bus/platform/devices/gta02-pm-gsm.0/power_on
echo 1 > /sys/bus/platform/devices/gta02-pm-gsm.0/power_on

Now you can talk AT commands to the modem to connect to the network
and exercise voice calls, either by running a terminal application on
the Freerunner's AP and talking to /dev/ttySAC0, or if you are running
a firmware version with the AT-over-RVTMUX feature, via fc-shell from
the external host.


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