Would like some experienced programming help or tips before I start please (just a sanity check!) My thought process is going along these lines:- Got the EM-406 GPS module working fine....so 1. Walk around the street and write (or data log) the longitude and latitude values onto an SD card as a 'numerical' map. I presume this data is best stored as an array? 2. Be able to read this stored data from SD card and compare it with an actual value from the rover then move to nearest 'match' value then follow the SD card data. I've sort of got my head round Section 10 and 10.4 of the book (Applying the ARM mbed) on Memory and Data Management, but I'm a bit stuck on the thinking process of reading data from the GPS module, compairing it and moving based on the error. Would the data first be stored as characters or floats in an array? I've had a look in the cookbook for examples of how to read from SD card and they are confusing me to be honest. So any advice or point me to examples to study would be greatly appreciated for now. Kind Regards Degs