There are lots of examples on the internet on how to program an Arduino as an I2C master to communicate with I2C slave devices. There are, however, very few examples out there on how to program your Arduino as a slave device. One of the best sites I’ve seen for documentation on I2C slave programming is over at Nick Gammon’s blog.
Well I thought I would take it a step further and put together a step by step guide showing you a real life example of how to make an I2C slave device using an Arduino. I did a lot of research while making my I2C GPS Shield and thought I’d pass along some of what I learned.
I just received the first set of boards for my new tracking device. They actually came in a little earlier then I had anticipated. Unfortunately I wasn't able to order the SIM900 modules in time because here at DSS Circuits we've been without power for several days due to a bad snow snowstorm so I had more pressing matters to attend too.
I've received many many emails regarding the Name This Board Contest so keep the entries coming, I'm going to leave it open until I have a working prototype.
And if anyone has any good leads on some cheap low volume SIM900 GSM suppliers, please feel free to drop me an email.