I've been researching for ways to make my own data acquisition device to monitor stuff around the house such as smoke detectors or anything else that could easily flip a relay or something, and also ways to monitor stuff like my server UPS's battery voltage so I can shut down the systems automatically and also monitor it.
I found arduino quite interesting and a Canadian site that sells it (Canakit.com) and bought the Uno.
I have another system in place right now for climate control that is not arduino but it's rather similar. Basically it has a bunch of temp sensors and relays that require their own 5v/ground source. Since I seem to be playing with lot of devices like this, rather than splicing all these wires to the common +5 and ground of the individual device, I an thinking of setting up some linked DIN terminal blocks for various voltages starting with ground, 3.3v 5v and 12v to use for these various projects. This will be provided by a computer power supply. Am I safe to use this voltage source rather than the source from the arduino board? Ground should be common across all devices right, it would be linked to the AC ground? Or could it be at a different potential and mess things up if I use it instead of the board's own ground? Or is there any reason I should not use an external source of power like this? If it matters it would be powered by the same server that the device would be plugged into via USB.
I already have a DIN rail setup so I can easily branch out to various sensors so figured this will be the cleanest way of doing it especially once I decide to add more arduino/other devices.
Also, is there specific pins I should avoid using? Some are marked with ~, what does that mean? I'm also guessing the pin 0 and 1 on the digital side cannot be used, right? They are marked RX and TX so I'm assuming they match with the serial?
Ahhh ok, so they're kinda spread out then, I thought the last block was those. Can those be set as normal digital inputs? In my case that's all I need. I think I read somewhere you can reset what a pin does.
Also is there any other pins I should avoid using or that are shared or have anything special? I am soldering them to terminal blocks which I will then label so I can make it easier to put crocodile clips for testing but I want to make sure I don't bother with pins I can't use.
RedSquirrel:
I an thinking of setting up some linked DIN terminal blocks for various voltages starting with ground, 3.3v 5v and 12v to use for these various projects. This will be provided by a computer power supply. Am I safe to use this voltage source rather than the source from the arduino board? Ground should be common across all devices right, it would be linked to the AC ground? Or could it be at a different potential and mess things up if I use it instead of the board's own ground? Or is there any reason I should not use an external source of power like this? If it matters it would be powered by the same server that the device would be plugged into via USB.
Providing the power supply can supply enough current for all devices it's fine to use only one. If there are multiple supplies you need to connect their gnd.
Good to know about the power supply. It will clean up my setup. So should I connect the ground from the arduino to my power supply's ground? Or will that already be done through USB. The USB will connect to the same server which will be providing the external power. I guess I could use a multimeter to check the potential and it should read 0 and the potential between the two 5v should also read 0, then I know I'm good. And yeah there will be plenty of current available.
RedSquirrel:
So should I connect the ground from the arduino to my power supply's ground? Or will that already be done through USB. The USB will connect to the same server which will be providing the external power.
I think it will be fine with the PSU already having a common gnd shared by both the USB and your external devices.