Arduino RX/TX pins to FT232RL Breakout Board

I am attempting to use a FT232RL chip to connect to a third party memory card writer. I eventually want to use the Arduino to control this memory card writer. I am having some issues so I would like to first make sure I can communicate through the FT232RL chip from my computer. This would allow me to manually send commands to the memory card writer and see what's going on.

I bought a FT232RL breakout board from spark fun.

I loaded a simple serial_write program and tested it via USB serial to the Arduino and Hyper Terminal.
Hyper Terminal connected with 8 data bits, 1 parity bit, 9600baud, and no flow control.
Works fine I see the output.

Next I would like to do this using the FT232RL and the Arduino RX/TX pins. This will prove to me that I can read from the FT232RL Breakout correctly using Hyper Terminal.

Plugged the FT232RL breakout into an Arduino Diecimila, as it provides a 3.3v power supply.
I plugged the RX/TX into the Arduino pins 0/1.
I start it up, and nothing.
Hyper Terminal is connecting the same way as to the Arduino directly.

Do I need to do something special in order to get Serial written to pins 0/1?


If the Decimilla's on-board FTDI chip is powered (IIRC if the power jumper is set to USB), then you'll have two devices trying to drive an input, possibly with conflicting values. If this is happening, I'd expect to see the Decimilla's output on both ports, but trying to talk to the Decimilla probably won't work.

Other than that, if you tie your FT232 breakout TX to the Arduino RX and vice versa, it should work fine.

I have a custom board that I'm using to develop software for a Vinculum VDIP1, and I do exactly that. I use software serial to send debugging data (eventually telemetry) to a serial port on the computer.


Hyper Terminal connected with 8 data bits, 1 parity bit,

Oops, I missed that first read - you should use no parity. The Arduino is 96008N1 (N is no parity).


I was powering with the power supply to avoid having extra USB serial connections.

I will try with no parity!

but it's odd how with the parity it worked when I had the USB connected to the Arduino board directly (rather than the FT232RL Breakout)

Make sure Hyperterminal is looking at the comport the breakout board FTDI chip is using. Windows does not always assign the same port to a USB device.

Darn I mixed myself up.
I never had a parity bit! I meant one stop bit.

I am playing with it now. There is only one USB device connected to my computer so it's connecting to the correct port.
No output on either of my FT232RL boards :frowning:
(I bought two to make sure one wasn't faulty)

Why does the TX led blink when I have USB connected to the arduino but otherwise it doesn't?
Technically it should still be writing to the TX pin right? Unless it's waiting for some kind of hardware synch.

I'm lost :-[

The TX LED (as well as the RX) is tied to/driven by the FTDI chip. If you aren't on USB power, that chip isn't powered and they won't blink.