FTDI NMEA to USB COnverter

[cblake]

I thought I would pass along my experience with FTDI's RS323 to USB adapter cable. I got mine from Mouser Electronics (Mouser Electronics - Electronic Component Distributor part number 895-TTL-232R-5V-WE).

One end is USB type A male. The other end is tinned wire.

I connected pin 2 to Data Out and pin 5 to Ground. The output I saw (using either hyperterm or tera term) was garbled. The problem was that RS232 wants 0 to -5 V and my instrument was putting out 0 to 5 V.

I was able to use a utility program from FTDI (http://www.ftdichip.com/Support/Util..._Prog_v1.9.zip User's Guide http://www.ftdichip.com/Support/Docu...or_FT_PROG.pdf) to invert the expected input on that pin and every thing worked.

I have only used this adapter to receive data. I don't currently have a need to transmit data, but if I find one, I'll report how it worked.

If your nav instrument actually uses the RS422 protocol called for by the NMEA standard, FTDI has a similar cable for that.

The part number above is for a cable with a black, opaque USB plug. There is a "BT" option that has a black cable and a transparent plug with a couple of LEDs in it. Besides letting you know the thing is working, it could provide a little entertainment on night watches.

I like this adapter since it is a single stage, single part solution.

Coleman Blake