I thought this was a great idea! And I've been wanting an excuse to hook my Arduino up to twitter for ages.
What you'll need:
- Arduino board (I'm using the Duemilanove)
- Ethernet shield
- LCD shield
- 3 push buttons (if your LCD shield doesn't come with them)
All the elements of this project are already widely available. People have been using the official Arduino Ethernet shield to sent Twitter updates for ages. My problem was that I bought the much cheaper, ENC28J60 based Ethernet shield by nuelectrnoics. It wasn't until tuxgraphics.org brought out their new TCP/IP stack, and Andy modded it for the Arduino that I was able to send Twitter updates from it.
The LCD shield also proved a bit of a hassle. Mine is also from nuelectronics and wouldn't sit properly on top of the Ethernet shield. The RJ45 socket from the lower shield is a lot higher than the pin headers, and there were some through-hole pins from the buttons poking through making it impossible for the two boards to mate.
I soon solved that though by desoldering most of the buttons, shortening the leads, and re-soldering them in a surface mount fashion. They work just fine, and the two boards will now mate (not perfectly, but enough to make a solid connection).
The code for my Arduino sketch is located here. Basically, you just plug the board into an Internet router (over a wired LAN), power the Arduino somehow, and then use the buttons to scroll through the possible tweets. Once you've found the one you like, click the send button and it'll post the tweet to your Twitter account.
I'd love to make this thing wireless, using a WiFi card. I bet they aren't cheap though....