Installing the Temperature Sensor

* install the tools that allow you to talk to the I2C bus:
sudo apt-get update
sudo apt-get install i2c-tools

sudo modprobe i2c-bcm2708
sudo modprobe i2c-dev

* add the pi user to the I2C user group:
sudo usermod -a -G i2c pi
logout

* Rev 1 board: receive input from the sensor and convert hex to degrees Celsius:
i2cget -y 0 0x48 0x00 w | awk '{print(("0x"substr($1,5,2) substr($1,3,1))*0.0625)}'


* Rev 2 board: receive input from the sensor and convert hex to degrees Celsius:
i2cget -y 1 0x48 0x00 w | awk '{print(("0x"substr($1,5,2) substr($1,3,1))*0.0625)}'

* Bash scripts to do above and handle negative temperatures:
* Rev 1:
#!/bin/bash
i2cget -y 0 0x48 0x00 w | awk '{printf("%.2f\n", (a=("0x"substr($1,5,2) substr($1,3,1))*0.0625) >128?a-256:a)}'

* Rev 2:
#!/bin/bash
i2cget -y 1 0x48 0x00 w | awk '{printf("%.2f\n", (a=("0x"substr($1,5,2) substr($1,3,1))*0.0625) >128?a-256:a)}'

* make script executable and run:
chmod +x tmp102.sh
./tmp102.sh

Posting the Temperature Data

* blank.json (replace YYYYY with datastream ID):
{
 "version":"1.0.0",
 "datastreams":[
   {"id":"YYYYY", "current_value":"T1"}
  ]
}

* make update.sh executable and run:
chmod +x update.sh
./update.sh

* run the script in the background:
nohup ./update.sh > /dev/null &

* stop the update.sh script:
killall update.sh