The Picstart+ is not designed for in circuit serial programming. It can do
it under some circumstances but the drivers are not powerful enough to
reliably work in this capacity. If there is other circuitry on your board
that can pull the supply down. The best bet is a Promate with the ICSP
adaptor. I know it is more expensive but it does work reliably as long as
you follow the rules.


At 02:18 PM 8/6/99 -0700, you wrote:
>Just a quick note in case this jogs anyone's memory:
>
>I'm trying to program a PIC16F877 on my board, it's a TQFP package, I
>have a 5X2 pin header for programming, identical setup to my last project
>using a 16F84 (jumpered for operation).
>
>I built a programming cable with a 40 pin socket on one end and a 5X1
>plug for the header on the other, I'm using a Picstart+. Again, this is
>the same way I did it for the 16f84.
>
>16F877s in a DIP package program just fine in the Picstart, but when I
>plug in the cable and plug that into a board I can't get it to program, I
>get various errors, including "Cannot Transmit", "Cannot Receive", just
>plain "Failure" in the program/verify window, and occasionally something
>like "Command 8F not echoed properly (F8)".
>
>Does anyone have any clue what might be wrong? Or suggestions on what to
>look for? The cable checks out fine with the ohmmeter, it's about 8
>inches long and shielded, so should be electrically fine. I'm stumped.
>
>Dave Johnson
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@ieee.org
http://www.ultranet.com/~nr