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Can program on pic family but not the other

Discussion in 'Electronic Basics' started by Abstract Dissonance, Mar 1, 2006.

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  1. I have sucessfully programmed the 16F688 but when I tried the 18LF4431 it
    does not work. I read both specs and they seem to be the exact same(ICSP?)
    and I have hooked them up right(pin wise) but when I use winprog to program
    the 4431 it always fails(and I did select the right pic in winprog).

    Only thing that has changed is that instead of 5.06V rail for the clock and
    data lines they dropped to 2.3V or something like that. (But I think this is
    in the limit for the LF?)

    Only other thing that I can think of has to do with setting the clock in
    winpic. Its set at LP but has many other settings... but not sure if this
    matters when programming as it uses the clock of the parallel port.

    I also have tried to delay up to 150us in winprog on the timing but it did
    not work.

    Any ideas? I figured the programming method would be the exact same(Except
    for pin layout) but something isn't working ;/

  2. Come on guys!! Can anyone think of a reason why a programmer would work for
    the 16F688 and not the 18F4431? As far as I can tell the method is exactly
    the same as outlined in the memory specifications of each document(aside
    from the communications which is handled by winpic). I'm using Byron's
    method by using a tri-state HCT device to buffer the lines between the pic
    and the parallel port. I have tried all different settings in WinPic but
    nothing helps...

    The pin connections are the exact same except for a rearrangement and having
    to ground the LVP pin... unless I'm missing something? Do I also need to
    ground all the other pins or the AVDD/AVSS too?

    (maybe there is something wrong with Winpic though? ;/)

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