I have been able to replicate your setup on the breadboard more or less, but only if I use separate jumpers. If I use two adjacent jumpers on a ribbon cable whose insulation is bonded together, it causes my chip to not be recognized every time for me. I have replicated this with my STm32F4Discovery Board and my ST-Link on my prototype. I also have replicated this (again) with my STm32F4Discovery tried to program itself through bonded jumper wires. I am reasonably convinced the jumpers caused the interference in each case. On Mon, Feb 2, 2015 at 1:41 PM, Daniel Serpell w= rote: > Hi!, > > > > I think that the capacity on the cables alone was not the culprit, > perhaps you have some resistors in series with the signals? No resistors are being used, I am considering testing those to see if they improve things though. > Here is a photo of my current (working) test setup, as you see, my > cables are similar to yours, and the board is not tidy :-) > > https://drive.google.com/uc?export=3Ddownload&id=3D0B1Uh9dgDfzYpSU5PbEp= Helk1OVk I was really shocked at first, because I was having trouble on the breadboard. But, now I have replicated your setup, being being careful about my jumpers (It just wont work with two joined jumpers). --=20 Jason White --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .