Arduino and FTDI Communications

Question

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?

• Chintalagiri Shashank: What exactly is an FTDI connector? Does it have an FTDI on board with a USB connector?
• GotWoods: RedGrittyBrick has the exact board I am using. It has an FTDI connector on the board.

Answer 1

"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.

Answer 2

Yes, see here for the schematic of the sparkfun FTDI breakout.

As you can see on the far right, the FTDI connector has 6 signals, two of which are RX and TX. Those are the ones you would want to hook your Arduino's UART pins to. However, depending on the complexity of the diagnostics program (the computer program you are supposed to use to issue the commands and parse the responses), it might be simpler to just pony up and buy something like the product I linked to.

• GotWoods: I agree it would be simpler but it peaked my interest to see if I could do it :D

Answer 3

Is the FTDI connector just a serial interface or is it something different?

The documentation for your WiFi shield (daughterboard) will answer this.

FTDI is Future Technology Devices International - a company that makes integrated circuits commonly used to bidirectionally translate between low-voltage serial communications and USB "virtual serial port" communications.

As far as I know, there isn't really any such thing as an "FTDI connector" but it is possible that phrase is being used for a connector for low-voltage serial data lines that can be hooked up to an adapter that uses an IC from FTDI (or equivalent IC from competitors).

I say "low-voltage serial" because historically, serial mostly meant asynchronouse serial, usually RS232, which specifies higher voltages than are typically availble in modern 5V or 3.3V microprocessors.

If the pins are labelled "TX", "RX" etc - it's probably low-voltage serial.

enter image description here

In the above board the 6-pin serial connector is labelled "FTDI cable" because it's pinout matches the popular "FTDI cable" product sold by Sparkfun and others.

So yes, If you have a computer or microcontroller device that has a low-voltage async serial interface, you can use it to debug your Wifi Shield.