If Arduino or ArduIMU is running, can i unplug/plug analog/digital sensors to pins?
I've never had any trouble doing that. When you breadboard, you are doing it most of the time. The only caution is think about the circuit before and after and try to imagine what could go wrong. The more that I know about electronics now the more I wonder why so many electronics are not hot pluggable, because most of the time there isn't much to go wrong. Especially for inputs on something like an Arduino that are high-impedance anyway. Assuming the voltages stay within limits. For output pins, you just have to make sure the physical plugging isn't going to connect the output to a low impedance route to ground or VCC.
For very complex systems like computers where they start drivers before the UI begins, maybe hot plugging isn't going to be feasible in simpler systems because of software, rather than hardware.
The other area where I can see a possible problem is on a true bus where all the participants to the bus have to behave and cooperate. Maybe when you just slam a card into a bus like that it isn't in the right state for a little bit and is connecting bus wires to ground or VCC directly, or otherwise interfering with the other sub-circuits on the bus. So I would be careful if the part of the circuit is acting as a bus with three or more sub-circuits participating. Otherwise, probably never an issue.
When in doubt, experiment on cheap parts and with 5 volts. Not too much can go wrong.
Making a bread board while it is powered up is a bad idea. Sooner or later you will damage something.
The problem with hot plugging is that the ground must be connected first then the power and finally the signal. Any deviation from that order could see your chip latch up or draw lots of current or be over voltaged.
Grumpy_Mike:
the ground must be connected first then the power and finally the signal.
And the reverse order to disconnect.
You usually have to reset the Arduino anyway when you do this, and sometimes power cycle it (by unplugging the USB).
Sorry for jumping in a few years later...
In a flying vehicle the involved micro controllers need to do their job in every instant of a second.
If a controller card is fried, a new one needs to be switched in on the spot to avoid the unthinkable.
Are there solutions out there for this kind of scenario?
Kind regards, Avian19
The Arduino is not suited for a safety critical system on an aviation system.
Grumpy_Mike:
the ground must be connected first then the power
Why? AFAIK there is negligible difference between GND -> power and power -> GND sequence. Maybe when using split power supplies but still...
Why is because of parasitic powering of the device connected to signals but no reference like power and ground.
This leads to latch up and possible device damage. Resulting in unreliable success in the hot plugging operation.
It is what is done in all hot pluggable devices. Look at the connections on an SD card or a USB connector. You will see the power and ground connections are longer to ensure they connect first.
Sure. In general it is "safer" to connect power pins first and signal later. (But there is the floating pins issue that needs to be addressed anyway...) But AFAIK there is no need to connect power pins in any fixed order. Connecting "power" first and GND second is as good as GND first and "power" second. Signal pins should be the last unless you know they are designed to be hot pluggable.
Look at it this way: If you hear it go "tick" or
see a spark, it is too late to say "OOPS."
Give yourself a second chance to get the
wire in the right hole before powering it up!
Herb