The Temp Sensor is an I2C sensor  Arduino is capable of turning the Arduino into an instant thermometer, plugging directly into Arduino Duemilanove or Uno Analog Pins 2-5, or just breaking out the native Arduino I2C pins (4 & 5) and powering the chip from anther source.

The TMP421 chip is a 12 bit I2C chip that works from minus – 40 to 125 degrees C, and the sensor is able to resolve .04 degrees C per bit. The absolute accuracy is guaranteed to be +/- 1 degree C. The relative resolution should make the sensor useful for a range of higher resolution activities such as sniffing out drafts around windows.

The Temp Sensor comes with a 4-pin male header (unsoldered) and 8 total pin-outs to allow for maximal flexibility in project use. With a small, narrow form factor, it’s easy to set up multiple Temp Sensors for local temperature monitoring as well.

A ready-to-go Arduino library is also available free for download  and off-the-shelf integration with any Arduino project.

The chip communicates via I2C and also has an onboard remote temperature sensing capability as well.

Specifications

• TMP421 chip
• 4-pin male header included (unsoldered)
• Communicates over I2C protocol
• 1 Bi-directional data pin
• 1 Clock pin
• Ranges from – 40C to +125C with +/ – 1C accuracy
• Optional remote temperature probe input
• I2C Digital Interface
• Arduino Pin Compatible
• +5V Tolerant I/O

Arduino Pin Mapping

Analog 2 = Ground
Analog 3 = Vin
Analog 4 = Data
Analog 5 = Clock

Resources

• TI TMP421 Datasheet
• Example code and library on Github for Arduino1.0