Hey everyone-
I'm trying to get "position" data from a single pot to two arduinos simultaneously (one mega and one duemilenove).
My initial approach was to read the pot with one arduino and then communicate that reading via serial to the other. When I got into it, to my Noob sensibilities this seemed annoyingly complex given that serial only can communicate a byte and unless i got tricky I'd be losing much-needed resolution.
So I tried linking the pot to both arduinos. I am now able to get stable, identical readings on both boards only when both are hooked to the same ground and +5 output pins to the pot are also linked to both boards.
My question is whether this linking of two boards poses any sort of potential problem, or if there is a simpler or more elegant way to do this.
You really only ever want to have one regulator driving a power line at a time, so you should NOT connect the two 5V pins together if you are powering both Arduinos via Vin (either the pin or the coaxial barrel jack) since Vin goes to the input of the onboard regulator which outputs to the 5v pin. You would in that case have the outputs of both regulators tied together which is inefficient at best, harmful at worst. You can power Arduino 1 via Vin, then bond the 5v and Gnd between it and Arduino 2 which would mean that Arduino 1's onboard regulator is also powering Arduino 2, or you can use a separate external 5v supply feeding 5v on both Arduinos.
In general, you only need a common ground, not a common +5V. So a typical dual-arduino setup would have independent power supplies for each one, with just GND and signals connecting them.