Nexus used the Bus Pirate with an MCP9800 temperature sensor and documented it on the wiki: The MCP9800 is an inexpensive, high-accuracy, 2-wire (I2C) temperature sensor. It features selectable 9/10/11/12 bit resolution with a typical accuracy of ±0.5°c at 25°c, programmable alarms, and low power consumption. We sent a free PCB code to say thanks! […]