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+--- Thread: CAN bus help and advice (/thread-20934.html)
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CAN bus help and advice - Blakey - 15-04-2021
I'm trying to monitor the CAN bus between the BSI and the MFD type A. The bus analyser did not like the connection so when I checked it with a scope the low was 12v driving to gnd and the high was gnd driving to 12v, so not CAN limits at all. On the bench the type A display is just blank, can't get it it wake up or display by sending any CAN data. I'm actually not sure of the correct IDs for the type A display anyway. Has anyone on the forum got any experience of this ?
RE: CAN bus help and advice - brajomobil - 16-04-2021
You need to connect to comfort CAN.
It is not "normal" CAN.
I did some test with Arduino + canbus reader but not got too far.
Did not find correct decoder. Connected in car to MFD Can wires
Other projects swamp me...
Best regards,
brajomobil
RE: CAN bus help and advice - Gryffindor - 16-04-2021
Up until roughly 2009, PSA cars had both canbus for mission-critical things and a proprietary vanbus (vehicle area network) for 'driver comfort' including the MFD.
They are similar in principle but differ in the detail, probably in the format of the data packets. It is nogh on impossible to find out specs for vanbus now because it has been deprecated (see below) so the websites which once covered it no longer exist.
But from roughly 2009 PSA dropped vanbus and went with only canbus.
So although you have a B9 and therefore probably canbus only, it may be worth checking that out exactly for your car.
If you do have vanbus, search this forum for that term.
I am still in research and theory mode with no practical experience, although I'm also intending to sniff the vanbus in my M59 with an Arduino when I can.
There are several Youtube videos on the subject - just search for vanbus, or for Citroen/Peugeot with canbus, etc.
RE: CAN bus help and advice - Blakey - 19-04-2021
Following some research the measurements match a "low speed" (125khz) CAN Bus. So I'm now making a interface to the type A display. Checking on the display PCB it uses a tja1054 from Philips, which is indeed a low speed bus driver.
RE: CAN bus help and advice - Gryffindor - 19-04-2021
Very interesting. Keep us updated!
RE: CAN bus help and advice - Blakey - 30-04-2021
Well, a bit of success. I made an interface to the low speed CAN using the same bus driver as the display and it now works fine. I can turn on the display on the bench, it sends about 6 frames of data, its present status, the time, serial number etc. I can send frames to display most of the warning messages, alter the temp display, but can't find the node ID for the date/time and the F to C for the temp setting. Guess I need the manual for the display if anyone can help with that?
RE: CAN bus help and advice - Gryffindor - 30-04-2021
I'm afraid I have never seen a full-blown manual for these displays, only basic operating instructions in the car handbook. Wouldn't both date/time and C/F be settable using the front buttons rather than programmed?
I'm only at basic theory, you are at implementation. Hopefully others can help you more...
That's some serious kit you have there - what is the little interface board you are using please? If it has the same chip as the display, I suppose you made it yourself?
RE: CAN bus help and advice - Blakey - 30-04-2021
Hi, yep I made the interface myself. Happy to post the circuit here in the near future (when I draw it up nicely!) It uses the microchip SPI interface and the low-speed bus driver, so it will work with raspberry pi or Arduino. You need two frames to keep the display awake, or it goes back to sleep mode. Remains powered and active on the bus when asleep. I don't have any buttons on my display. I think that the radio sends the time/date to the display, (not scheduled) where it is kept, the display sends the time/date every 1000ms, (presumably to the BSI, or anything else), I can read that, just can't change it.
RE: CAN bus help and advice - deejay_xb - 30-04-2021
time / date and other display settings like C or F are stored in the cdplayer
RE: CAN bus help and advice - Gryffindor - 30-04-2021
The circuit would be very welcome for me, though maybe too much for some forum members.
Aren't the three holes on the left meant for push buttons? I admit that in your photo they could be taken for bulb holders, but other pics (for example https://www.ebay.co.uk/itm/254529516933) show pcb tracks in them, which would be commoned together by carbon pads or similar on the ends of push switches.
Edit: inserted eBay pic for ref when the item is no longer listed.
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