Copyright © 2007 Mark Feldman. All Rights Reserved.
I've tried maybe 7 or 8 different "simple" PIC programmers I've found on the net, but none of them have worked with my main development machine. Low serial port voltage is the usual problem. After some reading and experimenting I came up with the following powered circuit which is very quick to breadboard and hasn't failed on me yet.
The voltage should be +5V regulated; 4.5V also seems to work fine. The circuit assumes you are using a regular 9-pin serial cable where each pin on one end is connected to the same pin on the other. If you are using a null-modem cable then you'll need to make a few minor changes: switch pins 2&3, pins 4&6, and pins 7&8. Use a multi-meter to determine what kind of cable you have, if those pins are switched around then it's a null modem. The following image shows a breadboard of the circuit for use with a null-modem cable:
To program the chip download a copy of PICPgm. It will detect the circuit as a JDM programmer and will support the usual functions of erase/program/verify. Simply load the HEX file and press the "Program PIC" button.
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