Short Version
Can I make a serial connection from an Arduino to a device with an FTDI connector?
Long Version
I have a wifi shield for an Arduino that is misbehaving. I know their is an FTDI connector on the shield that you can use to do diagnostics on the chip but I do not have an FTDI cable at the moment.
Is the FTDI connector just a serial interface or is it something different?
If it is serial would it not be possible for me to actually write an application for the Arduino that would issue commands over the FTDI connector for diagnostics purpose?
Best Answer
"If it is serial would it not be possible for me to actually write an application for the Arduino that would issue commands over the FTDI connector for diagnostics purpose?"
Yes. You would need to implement a second UART or Serial port, as the hardware serial port on the Arduino is tied to the serial/usb connection. The original serial port talks to your computer, and the second talks to whatever serial device you would like, in this case, the wifi shield.
See http://www.arduino.cc/en/Reference/SoftwareSerial for a software uart.