Hi Harley,

What J1850 protocol do you want to support? Or both PWM and VPW?

I had designed one product using PIC16F876.  It supports J1850-pwm 
J1850-vpw and ISO9141-2/14230-4 protocols.  The timing is ok for VPW and 
ISO but is a little tight for PWM even with 20MHz clock.  I have to 
disable the interrupts when receiving a PWM frame which is 41.6kbps with 
a pulse width of 8us on some symbols.

Right now, my client wants to add CAN interface.  I may have to switch 
to PIC18F2480 that is pin compatible with the PIC18F876.

regards,
Reggie

Harley Shanko wrote:
> Curious if anyone has ever run across/done a design (HW/FW) for a PIC-based
> OBD II for GM vehicles (uses the J1850 standard)?
> 
> I've been using PIC16F87x for several years.  Probably is overkill for this
> project, but have some pcbs which probably could be used to prototype such a
> design.  Save doing a pcb for it.  To start it would probably display on a 4
> line x 20 char LCD.
> 
> Any ideas, suggestions, etc. would be greatly appreciated.
> 
> Harley
> ps - this is mainly as a learning experience 

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