pic18f4550 with jdm cant verify

Thread Starter


Joined Feb 9, 2012
let me go over the basics
-using a home built JDM programmer
-has worked on 16f877, 16f6228 (so i know the hardware works)
-software: icprog and picpgm

i came across this (http://www.instructables.com/id/JDM2-based-PIC-Programmer/) which mentioned putting a 22pF cap from the PGD and PGC to ground aswell as a 100 ohm resistor in series with PGD to act as a filter. i am assuming that ground is the VSS wire. i also came across another source that said to use an external 5V supply for the VDD and VSS, tried that aswell, still nothing.

This has not worked for me, so i am at a loss and asking for help

It says it writes everything to the chip but when it tries to verify it fails every time, this happens both with my 18f2550 and the 4550.


Joined Oct 29, 2009
1. Open your waste can

2. Place programmer inside

3. Buy a pickit 2 or Pickit 3.

3. Keep your sanity and enjoy working with Pics as opposed to hating it.

It is just not worth the hassle. The Pickits have in circuit debugging and programming. It makes your job so much easier. The PicKit 2 even has a logic analyzer that will make troubleshooting problems so much easier.