[Chris] wrote us to share a neat technique he has been using to program the Arduinos he uses in his projects. He likes to build bare bones Arduino clones rather than sacrifice full dev boards, and instead of programming them via traditional means, he is using his computer’s sound card.
He builds a simple dead bug Arduino (which he calls an Audioino) using a handful of resistors, a pair of caps, an LED, a reset switch, and most importantly – an audio jack. After burning a special audio bootloader to the chip, he can connect the Arduino directly into his computer’s speaker port for programming.
Once the microcontroller is connected to his computer, he runs the IDE-generated hex file through a Java app he created, which converts the data into a WAV file. With the Arduino put into programming mode, he simply plays the WAV file with an audio player, and the code is uploaded.
He says that this method of programming comes in handy in certain cases where he builds things for friends, because they can easily update the software on their own without a lot of fuss.