Had one of those heart stopping moments over the weekend. I had an Arduino connected to my laptop via USB and a shield consisting of little more than sockets providing interconnections between the Arduino and up to 4 EasyDrivers connected to a 12v battery.

As I tried uplugging an easyDriver from one header to another I think I got the pin alignment wrong and my laptop went stone dead without so much as a whimper! As this is my all singing and dancing, video editting HP beasty I was somewhat concerned.

Fortunately removal of both the mains supply and the battery reset what was obviously a power supply trip and all is now OK. Except the Arduino won't upload a new program and gives me verification errors when I try. Whether this is a sick 328 chip or something else I won't know until a replacement arrives from RS.

So the lesson learned is the one we all know anyway but are often too impatient to ignore:

DISSCONNECT THE POWER SUPPLIES BEFORE BREAKING/MAKING CONNECTIONS! And remember that includes the USB lead as well.

I really will get Pipsqueak working properly one day but it's not cooperating right now.

Kit

I like to use my old mostly useless netbook for any experimental work for that very reason.