I built a mobile app to read data from blood glucose meters. It used a magic cable that talked to the meters using RS-232 and converted the data into audio, pl

I built a mobile app to read data from blood glucose meters. It used a magic cable that talked to the meters using RS-232 and converted the data into audio, plugging into the audio jack on the phone. So, basically, it was a modem. The cable just had a little bump on it that did everything you used to do with a huge device.