Just finished a class project where the goal was to make something with the NDS lite. We used an ESP8266 to create an open wifi which the nds connects to using dswifi9. Data is sent from the ESP to the nds and displayed on the main screen in a "cockpit" like style. A CSV of received data can be exported to the SD card too. The ESP can be connected to a vehicle like a rover via UART to send/receive control/sensor data.
It's not the prettiest code
but maybe it can serve somebody looking for example code for wifi or fat.Here is the repository.
http://github.com/octanisorg/rovercockpit
And a video of it in action:
https://www.youtube.com/watch?v=65KgiTxEQdc
HUGE thanks to the authors of libnds and co! Truly and amazing job you did and I had tons of fun with it!
Happy to get any suggestions or questions!