How to turn off all power to Arduino Uno when making breadboard connections

Hello to all.

I've just started using the Arduino Uno (I'm making the transition from the Basic Stamp) with my Dell Latitude D630 running Windows XP. While doing some wiring changes on a breadboard I've noticed that there appears to be no way to turn off all power to the Uno without physically disconnecting the USB cable. I assume that, like most microcontrollers, the Uno will not be happy having multiple connections being made while power is still applied to it.

So, is it possible to turn off all power to the Uno while still keeping the UBS cable connected? Can the Uno be damaged changing connections without turning off all power to it? How do you handle this situation?

Thanks!

Martythed

Hello,

Martythed: I assume that, like most microcontrollers, the Uno will not be happy having multiple connections being made while power is still applied to it.

As long as the voltage is within range (-0.5 to 5.5 relative to GND) the microcontroller wont care.

So, is it possible to turn off all power to the Uno while still keeping the UBS cable connected?

I've never had problems doing that. But I rarely do that.

Can the Uno be damaged changing connections without turning off all power to it?

Not simply by changing connections. A misconnection can damage it. But that's always true. There are two added risks when making live connections: 1. You will drop a live wire where you shouldn't; 2. There is no opportunity to review the connections before power is applied.

I try to do the "right thing": disconnect power, change connections, carefully review, apply power. Which is tedious. So I typically drift back to fiddling with live wires (5 volts). But I have a powered hub providing some protection for my computer and I always do the right thing when working with voltages above five.

How do you handle this situation?

Keep a few replacement parts on hand. Use a powered hub. Do the right thing when the risk is highest (voltages above five; lots of fiddly connections; new / unfamiliar circuit).

Coding Badly:

Great answer CB.

I searched the Net looking for info on this subject and, while there's a lot out there, most of it wasn't all that helpful.

As far as using a powered hub.......................arghhhhhh!!!! I should have thought of that myself.

Thanks again for the quick reply.

Martythed