At 05:20 PM 3/17/97 -0800, you wrote:
>Hi all,
>
>I'm trying to program a 16C84 with a low cost PARALLAX programmer
>and have some trouble:
>        1/ I'm obliged to program 3 or 5 times the chip to have
>the oscillator programmed for CRYSTAL and not RC
>        2/ I have the programmed chip (SMD), then sold it onto the board.
>I connect RB6,RB7, MCLR and VCC to the programmer in order to modify
>the program. Problem is as the chip is programmed for Crystal oscillator
>the programmer as many difficulties to read and program it.
>
>Does anybody know if it's necessary the oscillator section run properly
>to re-program a 16C84 ?
>Does somebody have the same problem with a parallax programmer ?

I used the schematic Microchip had in the data sheet with the Parallax
programmer, and it works very well.  Perhaps you have RB6 and RB7 in
contention with another device on your target board?

You DON't want the oscillator running at this time.  You can accomplish
that by simply grounding pin OSC1.

Andy

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Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
          Hardware & Software for Industry & R/C Hobbies
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