What every new system design has in common these days is wireless. Like bacon, it just makes everything better. Put a sensor wherever, read it from somewhere else. Put the power and control where you need it. For the CuPID/Pi, it is no different. We want to put our remote sense and control modules out into the wild and read and aggregate them as it makes sense.
Our basic system layout is as below. We’ve got multiple wireless nodes that broadcast data periodically, and a controller/aggregator that will log this data, acknowledge receipt, and do something useful with it. Eventually, we may have intermediate powered nodes that serve to mesh the grid out, but for now, our nodes just send data to the controller.
We’re currently using these awesome little RF units, called Moteinos. They are an Arduino clone that can use the standard IDE with their bootloader. They’ve got the ever-so-popular ATMega328P chip that is familiar to anybody working with an Arduino Nano or Uno. The Moteino comes with an RF board using the SPI bus of the microcontroller, available in various frequency flavors, and also in two different power varieties: one for maximum range, and one for maximum battery life. The whole thing comes nicely arranged on a PCB with a built-in voltage regulator, headers to connect our FTDI cable for loading and diagnostics, and an antenna. All for about $20. Really a fantastic deal .. and great customer support. Please patronize them.
For more detail: Adventures in Moteino: Remote Temperature Monitor