Hello Eelke,

Sorry for the late response. All my stuff was packed away as I moved house.

A picture of the display is attached.

I've wanted to interface to the display since I purchased the car. I could
not find anything anywhere which explained the way to talk to the TID. All I
had was some clues from the naming of the signals (SDA, SCL, etc.) which
would suggest that it was probably I2C.

I then found the Opel forum site. No one would openly help me or give me
hints, thus I decided to reverse engineer the communications between the
radio and display.

I borrowed from work a Hioki HiCorder wave recorder and logged the power-up
sequence of the bus. You could see the diagnostic pulses and initialization
of the bus. I also confirmed that the bus was I2C and noticed how the MRQ
behaved.

Anyway, knowing everything now I worked on the code and implemented an I2C
controller and display formatting module (flashing text, scrolling, refresh
updates etc.).

The TID is capable of having its time set via RDS. In order to get this to
work you need to unlock the "Global RDS" feature by holding the buttons in a
certain way. Once unlocked you can send a special datagram to the display
which contains time and MJD date format as sent by RDS.
I found out that you need to change the locality of the TID using a TECH 2
tester. I haven't tried this yet - I'll inform you of my progress.

Regards,
Luc.

In a second e-mail Luc told me:

The protocol for a 10 digit display is as follows:

START, Addr, Sym1, Sym2, Sym3, Char1 .... Char10, STOP

The address byte is 0x4D (0x9B with parity bit) for 10-digit displays. In
all, you should send 14 bytes to the display.

You will also find that 10-digit displays also respond to 8-digit datagrams.

Here's another picture for your webpage. It shows some extended characters.

I plan to use the display for a trip computer. The core code is nearly
completed, it's now a matter of creating a decent menu system and
fine-tuning some calibration tables and calculations.

I hope this helps.

Regards,

Luc