David Gröger

K70 CAN Bus

Discussion created by David Gröger on Jan 7, 2014

Hey everyone,


I've been trying for a few weeks now to get the CAN bus working but I've had no luck yet

and that's why I'm asking for your help.


My Setup:

Code Warrior v10.3 + ProcessorExpert

K70 MCU + TWR-SER boards plugged together with the elevator boards

mini USB connector for power and data transmission


There are mainly two questions I have:

Looking at the schematics, the CANH and CANL signals travel from the TWR-SER

board CAN connector, go through the transceiver, into the PCI bus (B41/B42) and from

there the signals go through a zero ohm resistor, namely R22 and R23 (and from there

to PTC 16/17 of the MCU). Schematics also says at the resistors "do not deploy". After

I measured the resistance of both resistors, I noticed they're far from zero ohms but a

few meg ohms! Is there a flaw in the schematics or didn't I think of something important?


Second question would be:

Where is the mistake in my code for the CAN bus communication? It's driving me nuts that

I can't measure any activity, neither at the CAN connector nor at PINs PTC 16/17 (=CAN1_RX

/ CAN1_TX). I use Processor Expert to generate the CAN driver functions. I attached the main

source code.


Any help is greatly appreciated.

Thanks, David.

Original Attachment has been moved to: CAN.zip