Using the FT232R to connect a USB port to the Garmin RS232 port
I'm currently working on a design for a project to connect the RS232 port on a Garmin eTrex GPS receiver to the USB port on a computer. I've settled on using the FTDI FT232R as the bridge between the RS232 and USB ports. I've currently got pinouts for the Garmin RS232 port (as it uses a proprietary plug, not a DB-9) and a USB port, and I've also located a datasheet for the FT232R. The FT232R datasheet has application examples which told me basically all the wiring that I need to do, but when it comes to connecting the RS232 pins, I encountered a problem:
According to the datasheet, the RS232 pins on the FT232R should be connected to an RS232 level converter. After researching what this was, I discovered that it is an IC used to convert the voltages provided by an IC (0 - +5) to those used for RS232 communication (-14 - +14 apparently), however, the GPS in question only uses 3V, so do I still use this converter, or do I use one with differant voltages (-3 - +3v?), or do I just omit the converter?
I've attached a GIF showing my circuit diagram so far. It shows the circuit based on the application example from FTDI including the level converter.
The CBUS pins have the following assignments:
I've also attached the datasheet for the FT232R in PDF.