We have a GPS device unit which has its own firmware, we know how to send and use every command, right now it is sending data to our server and everything is working well. What we need is to create our own firmware, which is to develop the communication protocol and changing the command format that is sent and/or received. Commands can be sent via SMS, GPRS, or connected to a computer through a serial cable.
We also would like a documentation or tutorial once the project is done, explaining to us what was the procedure applied in changing the firmware since so that we can duplicate this same process from the one provided.
More details will be provided after signing an NDA.