I was looking for a cheap USB to Serial TTL cable that would have a 3,5mm audio plug on its end. Such a cable can easily be found on Amazon for 23,27€ which is just a road robbery. Having an old audio plug the same cable can be constructed for only 6€ and here is the algorithm:
- Buy this Nokia Data Cable (or similar but it should be compatible with CA-42 or DKU-5).
- Cut the Nokia data connector out
- Solder an audio plug
- Profit (17,27€)
- Black = Ground
- White = RxD
- Red = TxD
The cable is 1m long, solid and reliable. Internally the PL2303 USB to Serial controller is used and its EEPROM isn't programmed by manufacturer so no additional drivers are needed on Windows or Linux. If the cable you use has PL2303 internally but its VID and PID aren't 067B and 2303 respectively and it isn't recognized on Windows then its EEPROM could be reprogrammed using this instruction.