Digital Temperature Sensor (MCP9808)

Summary

This I2C digital temperature sensor is a high accuracy (±0.25°C), high precision (+0.0625°C) device, with a temperature range of -40°C to +125°C. Temperature measurements are based on silicon bandgap properties. There are 3 address pins so you can connect up to 8 devices to a single I2C bus without address collisions. A wide voltage range of 2.7V to 5.5V allows use with a wide variety of 3.3V and 5V logic devices.

Unlike other digital temperature sensors, like the commonly used DS18B20, it does not come in through-hole package and is most conveniently used on a breakout board PCB. The PCB includes mounting holes, and pull down resistors for the 3 address pins.

The MCP9808 can output an alarm signal (ALERT) when the temperature changes beyond the specified boundary limit. The user can choose to set the alarm output signal polarity to an active low comparator or active high comparator output for thermostat operation or as a temperature alarm interrupt output for a microprocessor based system. The alarm output can also only be configured as a critical temperature output.

Technical specs:

Sensing Temperature: -40ºC ~ 125ºC
0.0625°C resolution
Accuracy: 0.25ºC typical
Voltage - Supply: 2.7V ~ 5.5V
Operating Current: 200 μA (typical)
Operating Temperature: -40ºC ~ 125ºC
Uses any I2C address from 0x18 thru 0x1F

How to Connect

The sensor has 8 pins: VCC, GND, SCL, SDA for I2C connection, A0, A1 and A2 to allow you to change the I2C address of the device (optional), and ALERT pin to allow you to set temperature thresholds (optional).

To connect to the Grove board:

Connect four wires to pins inside one of the I2C sockets on the central portion of the board (top right)
Connect left-most wire (GND) to GND pin on module
Connect the second-left wire (VCC) to VCC pin on module
Connect the second-right wire (SDA) to SDA pin on module
Connect the right-most wire (SCL) to SCL pin on module

How to Use

In XOD:

Matt Wayland has created the wayland/mcp9808-thermometer library to use this sensor in XOD. Use the thermometer node from this library with the default address of 18h. The TempC pin will read out the temperature in degrees celcius.