Databyte 0:
Possible meanings:

Databyte 5:
Lights:

The bit wise info for the lights byte is correct in my car

Databyte 1:
Related to engine startup, maybe 0x02 for engine on?

Databyte 3:
Toggled when starting engine?

Databyte 4:

key in ref 5E4 byte 1 which goes from 20 to 00 in similar time period?

Databyte 5:
Handbrake

Databyte 6:

Databyte 8:

Databyte 9:

01=door open
41=ESP/ASR deactivated
44=auto lighting active
45=auto wipers active

I suspected this was mostly for the benefit of the multifunctional display - but it doesn't get acknowledged or ask for one! (well not with the engine off anyway)

Databyte 0:
Part of header footer pair for message (starts and ends in 87) - this is another *data updated* header and footer
These headers and footers are common to many messages that carry updated information

Databyte 1:
D1 = Radio frequency data (probably for radio display)
D3 = Radio preset data (probably for displaying preset choices when you scroll the remote wheel)
D6 = CD track info

When D1 - Frequency data (like Example 1 above):

Byte 7:
Icons

When D3 - Radio Preset Data

Byte 2:
Preset number and type

When D6 - CD track info (I've not logged one of these yet so there's no example packet - take with pinch of salt)

I think total CD minutes:seconds are in there somewhere too, possibly the number of CD from the changer too? All seems to be BCD though so you can read the numbers directly.

Probably requested by multifunctional display?

Databyte 0 and 26:
Header & Footer sequence byte

Databyte 7:
Doors open

Note to self: check petrol cap and glove box to see if they modify this

Databyte 10:
Buttons

Byte 0 - I've seen it change from 20 to 00 in a capture where key was removed and capture left running
reference 524 Databyte 4 with my key in guess???

Bytes 0:1

00 01 - Sent by display during power up before it's ready to display anything
20 1E - Display is ready
20 1F - ?
20 FF - ?

Databyte 0:
Buttons 1

Databyte 2:
Buttons 2

Suspect this is broadcast by the dash board dials

Each packet is bound by a header & footer of the same byte.
I shall roughly decode these as they are ASCII displayed by the screen during destination setting.

Example 1:

This contains 3 of my destinations stored in memory (as it happens the first 3 to be displayed on opening the satnav screen)

Example 2:

Being a recent destination area - this pops up on my satnav screen when you go past choosing a memory and into looking up an address.

Example 3:

Hmm, 2 possible house numbers? I can't remember what comes on the screen next!

Example 4:

This looks like me entering an address

Example 5:

This looks like it follows on from Example 4

The packets appear in sequence and example 5 is regularly on the bus after I set a destination, the car was in a garage though so had no GPS reception, and couldn't start directions - I expect more packets like these once navigation starts. This seems to be the display reading what to show.

Header&footer seems to run from 0x80 to 0x87 over some captures accompanied by some bit changes (LSB bytes 1 and 2)

I guess this must come out of the BSI via the ECU

Databyte 0:

Databyte 1:

I guess this must come out of the ECU via the BSI

Databyte 2:
Buttons pushed

First AND mask the byte with 0x1F then:

0x01 = 1
0x02 = 2
0x03 = 3
0x04 = 4
0x05 = 5
0x06 = 6
0x10 = audio up
0x11 = audio down
0x16 = audio
0x1B = radio
0x1D = CD (maybe tape on other units?)
0x1E = CDC

OR/AND

Bytes 2 and 3 like so...
 

C2 11	“Audio setting down button” pressed (note: only sent when changing audio settings)
C2 12	“Audio setting up button” pressed (note: only sent when changing audio settings)
C2 16	“Audio button” pressed
22 13	“Seek- button” pressed (note: only sent when cdc input is active)
22 14	“Seek+ button” pressed (note: only sent when cdc input is active)
22 17	“MAN button” pressed (note: only sent when cdc input is active)
C2 1B	“Radio button” pressed
C2 1D	“CD button” pressed
C2 1E	“CDC button” pressed
	Notes for the keys above:
	1. When a button is released, bit 6 of the second byte is set (for example C2 5D when “CD button” is released)
	2. If a button is pressed longer than 2 seconds, a new packet is sent with bit 7 set, then also bit 6 is set and a new packet is sent every second. When the button is released, bit 7 are set to zero and a final packet described in note 1 above is sent.
21 40	Volume knob has been turned
24 40	Either RDS or TA button has been pressed and released

The port also tells the display to read new data (for example RDS data or cd time information) from port 0x554.

 

I can't begin to decode this until I put the headunit back in the car.

Taken from old rt3 wiki, I have not confirmed this data

I'm not convinced, this doesn't appear on the bus all that often - I guess once a minute is enough tho...

Also the info I've seen from other people is that the hours and minutes are in BCD... I have two captures from my car that are NOT BCD???

Databyte 0:

bits 4 and 5 are set in some way when you roll the wheel position past 0x00 or 0xFF and the number is reset to 0x80. I suspect some mechanism that says which direction it rolled over in to allow you to keep track of the wheel rotation.

Transmitted regularly by the stalk - all but bits 4&5 are understood, I think bit 0 is a spare for some other button.

Regularly broadcast, once again, no ACK requested - probably from ECU via BSI

This may be part of the radio security... only run if it sees a matching VIN on the bus.?