ibus clock, more info
The circuit design is my own.
It comprises an Ibus integrated circuit[Melexis TH3122], a microcontroller[PIC16F88] and a realtime clock chip[DS1307] with associated crystal and battery backup.
Kiwijochen provided me with the necessary info on the ibus messages involved in setting and displaying the time and date on the boardmonitor.
Jochen's help enabled me to write the software to program the microcontroller.
The software receives and decodes all messages on the bus.
On startup the navcomputer requests current time and date from the IKE [Instrument Cluster].
My circuit intercepts this request and replies, pretending to be the IKE.
After that it broadcasts the time and date message every minute.
Synchronizing to GPS time is a 'sexy' feature but the circuit works fine without it, with an accuracy equivalent to a quarz clock.
The Melexis TH3122 chip is difficult to source in small quantities. I got mine from Rolf Resler [the IBUS interface guy] at 10 euros a piece ex postage.
Soldering this chip is not everyone's cup of tea.
If sufficient members are interested I could have some pcb's made by a pcb shop.
Don't pin me down but I would 'guesstimate' a minimum cost of 50 euros for the board plus the parts.
Note:
The tripcomputer display and timer/stopwatch function on the boardmonitor should work but I can't be sure because I do not have it in my Instrument cluster.
Let me know what you think.
Hans
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