DSdiag is a Nintendo DS Diagnostics Tool. It allows the user to check backlights, check if their device has a compatiable FAT driver, test the SRAM, check if their audio hardware is functioning correctly, check if their device supports GBA modes, tests WiFi by getting the DS’s IP address, check for a Motion Card/Pak/MK6-Motion, check if there is a Rumble Pak inserted, check if their flashcart supports reseting from homebrew, tests the microphone to see if it is working, checks if the internal BootLoader of the GBAMP is functioning correctly by boot a .nds file of choice. DSdiag also writes the test results to a UTF-8 encoded plain text file. It also features a nice, clean Metroid-like theme.

http://gbax.gp2x.de/gbax2007.html