The firmware (0110514B.HEX) includes both the audio recorder/playback code as well as an SD card bootloader, to allow future firmware upgrades to be performed by placing the new HEX file on an SD card.

To upgrade using this bootlooader, place the new HEX file in the root directory of an SD card and name it "PIC32TSR.HEX" (TSR = Touchscreen Recorder). Remove the unit's battery, insert the SD card, then re-insert the battery.

The LED will flash at about 2Hz to indicate the PIC32's flash memory is being erased, then it will flash more slowly as the new firmware is being written. Once this is complete, it will boot into the normal interface. At that point you should remove the SD card and delete the HEX file, otherwise it will re-flash its memory the next time the battery is changed.

If there is an error during programming, the LED will flash at a much higher rate (about 8Hz). Possible causes of error include a corrupt HEX file or error reading from the SD card.

If the unit is booted without an SD card present, or there is no file called "PIC32TSR.HEX" in the root directory, when the battery is inserted, the unit will go straight to the normal recorder interface.
