19 December 2011

UV-3R data cable (homemade)

I had ordered an USB-to-UART TTL adapter to debug the rotary encoder on the Frequency Reader. While it was on the way to my lab, I solved the encoder problem, so the adapter had to be tested somehow.

Around the shack I had found a cable terminated in a 4-way 3.5mm jack, probably from an old digital camera. That is the connector of UV-3R data cable (and external ear/microphone too), so I gave it a chance. Steps were:
  • identify which cable goes to which connector ring
  • draw a map of pin matches between the cable and the adapter
  • test the whole thing (as shown in the picture)
My ugly UV-3R data cable (not for permanent use)
At first there was no communication with the radio. Then I swapped RXD and TXD connections: UV-3R software downloaded radio parameters. Cool. Note that the UV-3R says nothing on the display about the data cable being inserted or ongoing computer communication. If data is uploaded to the radio it will automatically power cycle.

The adapter is based on the CP2102 chip and costs 3 USD (2.3 EUR) shipped from Hong Kong. Both WinXP and Vista 64bit recognized the device (XP grabbed the driver from an online source).

The same adapter can be used to build a data cable for the FT817, or other transceivers that expose a serial port with TTL logic levels instead of RS-232 voltages (ICOMs, ...).