Using TX/RX serial pins to communicate over USB

Question

I'm using an Arduino Nano with an Atmega 328p.

I would like to attach and use a different USB port instead of the builtin one for supplying power, serial debugging and uploading code.

Currently my board is recieving power from the USB port using vin, but I would like to know how I can get the Arduino to use serial communication with the TX/RX pins and the data+ and data- pins on the USB. I'm especially interested in knowing if I can upload new code to the board through TX/RX.

The official page for the Nano says that the serial communication is handled by an FTDI FT232RL chip, which as I understand, translates the signal from the builtin USB to serial. Is there any way that I can use this chip to communicate over the TX/RX pins instead of builtin USB?

Online documentation about this subject is really lacking, and of the few opinions that I've found, many are conflicting. I would really appreciate any help with this, thanks.

• Juraj: why do you want to use a second FTDI?
• Mat: Are you looking for something like this: obdev.at/products/vusb/index.html ? Not quite clear to me why you don't want to use the builtin FTDI and associated Adruino tools
• chrisl: Instead of moving the data connection, wouldn't it be easier to add a second USB port for the power supply and connect it to the 5V pin?
• Gerben: Unrelated; you shouldn't connect the the 5V from the USB to the VIN pin. Connect it directly to the 5V/Vcc pin. The VIN pin requires at least 7 volts, and will regulate this down to 5V. Since you already have 5V you can bypass the regulator.

Answer 1

There is no "built-in USB" on the Nano. There is only the FT232RL chip which talks USB. That chip is connected directly to the TX/RX pins inside the board.

You are already communicating over the TX/RX pins through the FT232RL to the USB.

Yes, you could use your own FT232RL (or FT232-like) board to communicate between USB and the TX/RX pins, but that will be exactly the same as using the one built in to the board - but without the convenience, and with the addition of more wires and expense. So pointless, unless the current USB connection is damaged in some way.

• SpiccyMayonnaise: Ah, sorry, my mistake. So, if I wanted to add an additional USB port, I would also need an additional USB to serial converter chip? Does the included chip only work with the included USB port? Sorry if my question sounded a bit odd, I'm a student and this is more of a learning exercise. Thanks for the helpful answer!
• Majenko: If you want to add an extra USB port you will have to use SoftwareSerial to communicate with some FT232-like board through other pins that TX/RX.