Andre Thomas wrote:

> Has anyone made a RS232 to CAN transceiver using a 18F458 (or something
> similar)  ? 

When you interface RS232 to CAN, you need to decide how to translate from
one to the other. 

One approach could be that you use a specific CAN message id, and translate
the CAN data that comes with that message id into/from RS232. That would
allow you to place a serial debug channel (which can be very convenient) on
the CAN bus, not requiring an additional serial debug interface in the CAN
equipment you are developing. 

Another approach could be to send CAN trace information over the RS232: a
timestamp for the received CAN message, the message id, the type of CAN
frame, and the data if present. This would be more of a CAN monitor. Of
course, the RS232 bit rates may not be up to the task if the CAN bus is
running at high speed. (Also valid for the first case, but to a lesser
degree, because the data on the RS232 is much less there.)

I agree with Ake that a working interface is a valuable help, but I also
think it's not imperative. You of course have to start out building two of
your devices, and they need to be able to send, too, if you don't have a
reference interface :)

Gerhard
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