Thank you for the quick reply. The unit in question is an Audio 10 CD Player taken from my car (a Mercedes W639).
While the unit is mounted in the car and working properly I measure 0 and 12 vold at pins C1 (canH), C2(canL)
Background info:
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The Becker unit (BE6019.. Cassette player instead of CD player):
User manual. Pinout at page 22: http://www.perfectmarketaudio.com/Audio_10%20Manual%20PDF.pdf
Schematics: http://codedradio.info/manuals/becker/BE6021-schematic.pdf
The BE6021 processing unit with CAN support: http://eedatasheet.com/pdf/MB90F549,FUJITSU,123793.pdf
The canbus transceiver: http://www.ec66.com/market/sheet/TJA1053.pdf
Why can not the CAN bus run at 12 volt ? The mcp2551 works for DC between -42 volt and +42 volt....
I'm trying to connect the mBed to a device controlled by a Fujitsu MB90F549. This unit runs at 12v.
I've tried to use a mcp2551, but the mBed/mcp2551 combo delivers canH/canL signals based on the USB 5v and the Fujitsu unit uses 12v.
Does anyone have a possible solution for this problem ?