To reply to a comment posted yesterday, this is the contraption I use to re-flash a JeeNode or JeeLink after the fact via its ISP connector:
It has two diodes, dropping the incoming 5V power from the programmer to around 3.8V – this turns out to be needed in the case of JeeLinks, which has the VCC pin on the ISP header connected to 5V instead of the 3.3V driving the ATmega. The high voltage was causing problems with logic signal levels.
The other component on the board is a 100 µF capacitor, to reduce voltage fluctuations (it.s probably superfluous, I added it while debugging the setup).
Here’s this “after burner” in action:
The long pins are at an angle, because that way they can be gently pressed into the holes and they will stay there during programming.
Like most hacks, it looks awful, but it works pretty well!
Thanks for this reply post ! I wondered how you’d keep the pins well connected when ISPing; now I know :)