I am trying to interface a 3.3v Arduino Pro to another device via the RX/TX pins. Using a purchased programming cable designed for the chip I am able to see the serial output just fine. But when I connect straight to the RX/TX pins and go through a serial-usb converter (which I know for a fact works fine) the output is garbled. I've tried pretty much all the serial settings (including the one that's supposed to work) and haven't had any luck. I guess my initial reaction is that the 3.3v signal needs to be converted to 5v or that there's some handshaking that needs to be implemented but I'm not really sure...