Trying to get Radicom modem working with Dreampi

[Bjurr]

Hello everyone!

tl;dr: my dreampi setup can't hear the dreamcast dial a number while it's outputting the dialtone.


Yesterday, I decided I wanted to party like it's 1999 again, so dusted off my Dreamcast and dug into my box of old and unused hardware to find a Raspberry Pi 2 and a usb modem. I'm using the Dreampi 1.9 DLE image hosted on dreamcastlive.

The modem is a Radicom (doesn't seem to be officially supported by dreampi) and gives the following output in lsusb:

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Bus 001 Device 006: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP2102/CP2109 UART Bridge Controller [CP210x family]

According to wvdialconf, it supports everything I need:

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pi@dreampi:~ $ sudo wvdialconf
Editing `/etc/wvdial.conf'.

Scanning your serial ports for a modem.

WvModem<*1>: Cannot get information for serial port.
ttyUSB0<*1>: ATQ0 V1 E1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 Z -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyUSB0<*1>: Modem Identifier: ATI -- 56000
ttyUSB0<*1>: Speed 4800: AT -- OK
ttyUSB0<*1>: Speed 9600: AT -- OK
ttyUSB0<*1>: Speed 19200: AT -- OK
ttyUSB0<*1>: Speed 38400: AT -- OK
ttyUSB0<*1>: Speed 57600: AT -- OK
ttyUSB0<*1>: Speed 115200: AT -- OK
ttyUSB0<*1>: Speed 230400: AT -- OK
ttyUSB0<*1>: Speed 460800: AT -- AT
ttyUSB0<*1>: Speed 460800: AT -- AT
ttyUSB0<*1>: Speed 460800: AT -- AT
ttyUSB0<*1>: Max speed is 230400; that should be safe.
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found a modem on /dev/ttyUSB0.
Modem configuration written to /etc/wvdial.conf.
ttyUSB0<Info>: Speed 230400; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

Following this, I had to modify dreampi.py slightly because it was expecting a serial device on /dev/ttyAMA0, and not /dev/ttyUSB0 (apparently ENABLE_SPEED_DETECTION=False by default ... not a big issue).

I tested the setup using a standard phone to see if a dialtone was heard and surely enough, it works.

Now, the problem I have is that while the modem produce a dialtone, it never hears what's coming from the Dreamcast. If I comment out the actual buffer write for outputting the dialtone wav (self._serial.write(byte) in the Modem.update function), then the dreampi can hear the dreamcast dialing 111-1111, and things want to move on. Unfiortunately, this is not possible with all titles as some of them expect a dialtone before starting to dial the number.

Anyone has encountered this issue? Any ideas on what I could try?

Thanks!

[peanut_unlimited]

just to rule things out, have we got a line voltage inducer incorporated in the setup?

[Bjurr]

Sure do! Also validated this usin a regular phone plugged into the modem. No VLI, no dialtone. Plug in the VLI, got the dialtone.

One thing I have to do is solder the VLI properly. It's currently on a breadboard and I'm wondering if I'm not introducing some noise as the dialtone sounds really harsh.