This is an easy first project to get your Freetronics LCD Shield up and running and presenting some real-world data.
In a nutshell, it's a temperature sensor with an LCD output. The model of Arduino board you use isn't too important, but my current favourite is the Freetronics TwentyEleven. The prototyping area on the TwentyEleven is really handy for soldering everything onto for the more permanent projects.
Because the LCD shield covers all the pins on the Arduino board, you need a way to connect your temp sensor jumper wires. I used a proto shield but soldered an extra strip of headers inside the main ones. This way I can still plug the jumper wires in once the LCD shield is on top. Once you finish prototyping, you can reuse this shield for the next project.
The DS18B20 temperature sensor uses just three wires and a 4k7 resistor. It's on a breadboard here but you could attach it to a cable (I've used them on the end of Cat5 cable up to 30m away from the Arduino).
If you plug the DS18B20 into the breadboard with the flat face facing towards you, the pins are 1, 2, and 3 from left to tight. Pin 1 (black wire) goes to a ground pin, pin 2 (yellow wire) is the data pin and goes to digital pin 10, and pin 3 (the red wire) goes to the 5V pin on the board. With a 4k7 pull-up resistor between pins 2 and 3 you're good to go.
Plug the LCD shield on the top (being careful of the jumper wires underneath) and you're ready for the software.
The Arduino environment has an LCD library built-in so it's easy to load up a sketch and have a play. You can find some example sketches under File>Examples>LiquidCrystal> in the Arduino development environment. There are plenty of examples of code for the DS18B20 temperature sensor out there too. Basically, any data you can get into the Arduino can be printed on the LCD screen.
This sketch takes some code I'd used previously to print the temperature at 5 second intervals to the serial monitor, and prints it to the LCD instead.
The LCD shield has 5 handy buttons so you could use it for input to the Arduino too. I'll be using this in quite a few future Arduino projects as a way to see what's going on, as well as telling the Arduino what to do.
Parts for this project: