I have a circuit that takes 12-15v input from a motorcycle and outputs to a WS8211 LED strip. I have four strips, two long (about 3 ft) and two short (about 1 ft). I want to isolate the strips from the Arduino nano but still be able to send data to them. The strips have could draw up to 3A, and so obviously I don't want to send that through the arduino.
The question I have is, should I connect the data ground and power grounds together, or keep them separate. My wiring diagram currently has the grounds isolated. Otherwise, what's the best practice to protect the arduino? Should I put a diode in somewhere, and if so, where?
EDIT: It's occurred to me that this might belong in General Electronics, as this is more about electronic theory as opposed to Arduino Nano.
I'm aware that they are common, but I'm talking about the connection itself. The grounds are already common by nature of the connection to the vehicle. There is a ground for power and a ground for signals/brake. But should they be common on the circuit side as well?
Your power feed looks completely wrong to me. First, R7-R8-D7 is not going to support enough current to power the Nano. Why didn't you just use a standard voltage regulator? Second, 5V isn't enough voltage to apply to Vin, you need at least 7V there. If you want to bypass the Nano onboard voltage regulator and run it from 5V, you should apply 5V to the Nano 5V pin.
Glad you mentioned that. I switched to a buck module for VIN. As far as the grounds go, I've decided to leave the grounds separate from each other on this circuit side. The grounds are common on the vehicle side, so no worries there. Thanks for the help!
I want to use the onboard regulator, but keep a constant voltage for redundancy. I could just wire 12-14V straight to Vin, but I don't want to wear down the regulator. I'll be running a LM2596-ADJ at 6-9V. On the off chance that a component fails and sends 12V straight to the arduino, I want it going through the regulator.
Normally the regulator can't support external circuitry running from the Arduino 5V. But in this case, you don't have much current draw, just the digital drive lines to the strips. I would wonder if the step down is really necessary in this case. Although it does add a layer of protection, it also adds an additional link that can fail.
Unless, there is additional stuff connected on J1 that uses significant power.
