3.3V programming with the Junebug / Inchworm

[blueroomelectronics]

I'll post more detailed instructions shortly but today I got a Junebug working with a 3.3V 24FJ16AC002
What's required is simply two 1N5817 diodes acting as clamps connected between 3.3V (anodes) and PGC, PGC (cathode)
There is a trick though, you must program the Junebugs 18F2550 EEPROM with a calibrated VDD value. I'll upload a small .hex file with this code this evening. I'm also working on a hardware mod (removing either the 1N5817 or BS250 to allow the PICkit2 software to self calibrate (jumper from VR2 @ 4.2V to act as a VDD source)
I've not tested the Inchworm yet but will later an post the results.

 

[blueroomelectronics]

Here's the schematic for anyone interested. As for the self calibrate my method didn't work but the EEPROM version does.

 

[akuinnen]

That's great. I'll have to pick up a LM1117T-3.3.

 

[blueroomelectronics]

Also get a spare 18F2550, you can program it with the PICkit2 firmware (using the Junebug) and then put the EEPROM data on it. An Intel hex editor can change the name from "Bill"