I can't get my relay to work. I've put the 5V output from my Arduino UNO into the VCC pin on the relay. Then I put the GND from my Arduino UNO to the GND on the relay. I have a LED inbetween so I can see I got both power and ground working.
Then I'm using pin 13 which has a LED on the Arduino board to have a digitalWrite (13, HIGH) go to the IN1 on the relay (I've tried IN2,3,4,5,6,7 and so on, none works).
Am I doing something wrong? Do I have to do something with the COM pin on the relay?
Then I'm using pin 13 which has a LED on the Arduino board to have a digitalWrite (13, HIGH) go to the IN1 on the relay (I've tried IN2,3,4,5,6,7 and so on, none works).
The image you posted indicates that the relay is active LOW.
Delta_G:
Yes the relay power needs to come from a separate source. If you try to power the relay through the Arduino then it is going to let the smoke out.
When you say there's going to be smoke, is that because the Arduino UNO can't handle it? Or is it because the USB power is insufficient?
What if I power the Arduino UNO with a 9V battery?
I don't know what my 2nd source of power would be or how I could solve this problem. If I use a laptop for Arduino UNO and a 9V battery for the relay I won't know what to do with ground/earth..
niss3:
When you say there's going to be smoke, is that because the Arduino UNO can't handle it? Or is it because the USB power is insufficient?
Both. The arduino can't handle passing through that much current and it is quite likely that the USB can't supply it anyway.
niss3:
What if I power the Arduino UNO with a 9V battery?
You mean the square one like from the smoke detector? Why does everyone want to go for those? Is it the handy clips on the top or something? That is like the LAST battery for any Arduino project. They can barely supply any current, can't turn a motor for more than a few minutes tops, and just generally suck and run down in minutes if not seconds.
If you're going for batteries, get AA or AAA so you can get some current out of them. 9V batteries don't have no power. They're just for things like smoke detectors that run on nothing.
niss3:
I don't know what my 2nd source of power would be or how I could solve this problem. If I use a laptop for Arduino UNO and a 9V battery for the relay I won't know what to do with ground/earth..
In my case it's because I bought one of those "Get started with Arduino" packages, and this is what I got with it:
So if I understood this correctly. The VCC is for powering the relay "magnets", and the COM is simply to power the signal to the relay magnets. Which means I should power the VCC with another source than the one I use for the Arduino UNO.
What if I would split the 5V before it reaches the Ardunio? Would that make it possible to share powersource?
COM is short for Common - ie common to all of the devices in the project. Everything has to have a voltage reference to something - in this case it is COM.
Yes you can split the power supply output to power both the UNO and the Relay PCB but you need to connect all of the COM together
Both Vcc and COM power the relays. If either is missing they will not energise. The signal to control the relays is via pin 13 in your case
