Can anyone identify the serial/encoding protocol this scoreboard uses?

[xyk2]

I am trying to decode a signal stream coming from a Nevco scoreboard controller:



Packets like this are sent every ~2.7 ms.

I suspect it is some sort of UART signal because it is on the RX line of a ATMEGA48, but I cannot identify the finer protocol details like parity and stop bits. All the combinations I have tried returns junk data, so it may be another encoding scheme. What's unusual is that the same signal is also sent to the MOSI pin of the microcontroller, but there is no clock signal anywhere.

A .vcd file: http://pastebin.com/nSFC7U7W.

The shortest pulses (both high and low) are always 8us in length.



This is what two packets look like. Anyone got ideas? 

[FrankenPC]

1-wire?? 

[abyrvalg]

Looks like UART at 115200 baud with 11 bit frame (so 1 start, 8 data, 2 stop or 1 parity of some kind, 1 stop), no?

[David_AVD]

Is the data connection between the controller and scoreboard hard wired or wireless ?

[GiskardReventlov]

Here's my guess, they are simply sending the 7-segment data.  Some DMMs do this for logging data capability.  There was a linux driver on github but I don't remember the name.

I recall that the DMM sends the coordinates for the segments. That is decoded into what you'd normally see on the display into usable numbers.

[SL4P]

Can you compare this to something else displayed on the board?
e.g. all 1's or all 0's
Then you may see the data change (I'd hope!)  Ideally triggering on a specific bit change - so you can start reverse engineering.  Dump in HEX would a benefit - rather than ASCII - since that's not showing anything so far.