To detect lengths of time elapsed you can use your TMR0 module.  Figure out
how long of a delay it is to signify the code is complete and watch for it.
To get 1 & 2 to be 12, simply make code detect that sequence, there can only
be a few error codes, so you could just code for each one if you wanted, to
brush up on your assembly :)

nick@veys.com | www.veys.com/nick

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Justin Fielding
> Sent: Wednesday, June 20, 2001 8:04 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [PIC]: 16F84 project for newbie....
>
>
> I am a newbie to Pic's (just got to the interrupts section in the
> Easy Pic'n book) and have thought of a great little project.  I
> want to make a fault reader for my car's ECU.
>
> If the ECU detects a fault (can be simulated by disconnectiong
> something) then it pops the warning light on.  You can then (bit
> of a quick hack) conect an LED accross two of the pins on the
> diagnostics port and short two out and it will flash a code on the LED.
>
> It first flashes 1 2 to let you know it is working, then the
> fault, say 2 6 and then 1 2 again.
>
> Trouble is it does this in a rather strange way, in the above
> example it would.
>
> Flash the LED once
> Short pause
> Flash the LED Twice
> Long pause (so the above was "1" then "2" but this should be read as 12)
> Flash LED Twice
> Short pause
> Flash the LED six times
> Long pause ( representing "2" then "6" or 26)
> and so on.....
>
> I would like to use an F84 with an input from the ECU (from where
> the LED goes) and then a LCD display to show what the fault is
> (use a lookup table here).
>
> Problem is how do I know the difference between the long and
> short pause (so I can stop counting flashes and move to the next
> digit) AND the big how... How do I turn "1" & "2" into 12 (for
> use in the lookup table)?
>
> Any help or tips from similar projects would be appreciated.
>
> Thanks.
>
> Justin.
>
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