Serial UART

Out of the box the FT232H is configured to act just like an FTDI friend USB to serial UART converter.  This is great for talking to a serial device like an Arduino from your computer.  It's safe to use with both 3.3 volt and 5 volt signals.  This means the FT232H breakout can used to safely talk to an Arduino's 5 volt serial ports, and a Raspberry Pi or BeagleBone Black's 3.3 volt serial ports!

When used as a serial UART the FT232H breakout pins have the following serial functions:

  • D0 - TX or transmit pin.  This pin is the serial data output by the FT232H chip and should be connected to the RX or receive pin of a serial device.
  • D1 - RX or receive pin.  This pin is the serial data input for the FT232H chip and should be connected to the TX or transmist pin of a serial device.
  • D2 - RTS or ready to send pin.  This is an optional pin for flow control of serial connections.
  • D3 - CTS or clear to send pin.  Like RTS, this is an optional pin for flow control.
  • D4 - DTR or data terminal ready pin.  Another optional pin for flow control in RS-232 serial connections.
  • D5 - DSR or data set ready pin.  Like DTR, this is another optional pin for flow control in RS-232 serial connections.
  • D6 - DCD or data carrier detect pin.  This is an optional pin that is sometimes used in RS-232 serial communication.

The most important and commonly used serial pins are D0 and D1 for the TX and RX pins.  The other pins are only necessary if you're using a device with flow control or specific RS-232 serial needs.

USB Serial Drivers

Before you can use the FT232H as a serial UART you need to make sure the proper serial port drivers are installed.  Luckily most operating systems include FTDI's serial UART driver so there typically isn't any installation necessary.

Specifically Mac OSX Mavericks or greater have the FTDI serial driver included automatically.  Linux kernel versions since ~2.6 also have the FTDI serial driver included, so modern Linux distributions like Ubuntu 12.04 or 14.04 should work without any driver installation.  Windows can usually search online to find the driver automatically, however if that fails see below for manual driver installation instructions.

If for some reason your operating system doesn't have FTDI serial drivers installed, you can download and install official drivers from FTDI's site.  There are drivers available for Windows 7 & 8, Mac OSX, and Linux.

Windows Serial Driver Installation

Below I'll briefly walk through installation of the FTDI serial driver for Windows since it is a common platform to install the driver.

First start with your Windows 7, 8, or 8.1 machine booted and the FT232H board disconnected from the PC.  

Download the FTDI serial driver (sometimes called VCP or virtual COM port) here, make sure to pick the Windows setup executable version of the driver.

Next open explorer and navigate to the folder where the driver executable was downloaded.  Right click on the file and select Run as administrator as shown below to start the installation.  It's important to run as administartor or else the driver installation will fail to copy files to Window's system directories.

Now click through the setup pages, read and accept the license agreement, etc. to install the driver.  The aren't any configuration or setup options you need to change or worry about in the installation.

Once the installation is done you might need to reboot your machine if the installation program tells you to do so.

After rebooting, plug in the FT232H breakot to your PC using a USB micro cable.  You should see a message pop up that the device is recognized and a driver is being installed.

To check that the serial port installed successfully and find the COM port assigned to it, open device manager by clicking the start menu and searching for Device Manager.

Inside device manager look under the Ports (COM & LPT) node and you should see a USB Serial Port (COMx) device, where x is a number like 5.  This COMx is the COM port assigned to the FT232H serial UART, and what you should use when connecting to the serial port in the Arduino IDE or with a serial terminal program.

However if for some reason you don't see the USB Serial Port (COMx) device or Ports (COM & LPT) node, you might need to enable the VCP mode for the FTDI device.  To do this open the Universal Serial Bus controllers node at the bottom of Device Manager and you should see a USB Serial Converter node.  Right click this node and click the Properties menu, then click the Advanced tab at the top.  Make sure the Load VCP checkbox is checked and then click OK.  See the picture below for the configuration page and device manager view you should see.

Now unplug and plug in again the FT232H board and check device manager again to find the USB Serial Port (COMx) node in the Ports (COM & LPT) node.  That's it, you're all set to access the device as a serial COM port in Windows!

Serial Usage

Once any necessary serial port drivers are installed, you're ready to use the FT232H as a USB to serial UART.  Let's perform a simple loopback test to confirm you can read and write data with the UART.  This test will connect the TX pin to the RX pin so any data sent to serial UART will be immediately received and echoed back to you.

Using a jumper wire, connect pin D0 (TX) to D1 (RX) on the FT232H breakout as shown below.

Now open a serial console for the FT232H board and check that anything you type is echoed back to you.

Windows

On Windows you can use PuTTY as a serial console.  Download and run PuTTY, then configure it for a Connection type of Serial as shown below on the right.  The Serial line should be set to the COM port you found for the USB serial converter in device manager (shown on the left), in this case COM5.  Speed should be set to 9600 baud.

Click open and you should see an empty terminal screen appear.  Try typing a message and you should see what you type echoed back to you, like below:

If you don't see anything, make sure you've connected the D0 pin to the D1 pin on the FT232H board.  

Also make sure you're using the right COM port for the FT232H device.  Try unplugging any other USB to serial converter (including development boards like Arduinos!) and only connecting the FT232H board to make sure you can find its COM port in device manager.

Mac OSX

On a Mac you can use a few included terminal commands to list serial ports and connect to a serial port to test the loopback connection.  

First start with the FT232H board disconnected and open a terminal to run the following command to list all serial ports.

Download: file
ls /dev/tty.*

You should see a list of devices, such as:

Download: file
/dev/tty.Bluetooth-Incoming-Port    /dev/tty.usbmodem20	
/dev/tty.Bluetooth-Modem            /dev/tty.usbmodem22	
/dev/tty.usbmodem1d111              /dev/tty.usbmodem24

Now connect the FT232H breakout to the computer, wait a moment, and run the same ls command again.  You should see a new device in the list, such as:

Download: file
/dev/tty.Bluetooth-Incoming-Port    /dev/tty.usbmodem20
/dev/tty.Bluetooth-Modem            /dev/tty.usbmodem22
/dev/tty.usbmodem1d111              /dev/tty.usbmodem24
/dev/tty.usbserial-0000111D

The new device, /dev/tty.usbserial-0000111D, is the FT232H serial UART.  You can use this device with a program like screen to open a serial connection.  Run the following command in the terminal to open the serial UART:

Download: file
screen /dev/tty.usbserial-0000111D 9600

Replace the /dev/tty.usbserial name with the name of the device you found after running the ls commands above.  The 9600 after the name is the baud rate to open the screen connection.

Once screen opens the connection you should see a blank screen.  Try typing characters and you should see them echoed back in the terminal.  Congratulations, your serial loopback test is a success!

You can exit screen by pressing Ctrl-a and then Ctrl-\.

Linux

On Linux distributions such as Ubuntu 12.04 or 14.04 you can run terminal commands that are very similar to those shown above for Mac OSX.  The only difference is that you should run the following ls command to list serial devices:

Download: file
ls /dev/tty*

Run the above command before and after plugging in the FT232H breakout to find the path to the new device that was added.  On a distribution like Ubuntu you will typically see a path like /dev/ttyUSB0.

To open the serial port use the exact same screen command as mentioned above for Mac OSX.  Replace the path parameter with the path to the FT232H device you found above.

Note you might need to press Ctrl-a and then \ to quit screen on Ubuntu or other Linux distributions.

Other Serial UART Uses

You can use the serial UART on the FT232H just like you would any FTDI friend or similar USB to serial UART.  Remember the FT232H breakout can work with 3.3 volt and 5 volt boards (that accept a 3.3 volt input as most do) so it's perfect for connecting to small embedded Linux boards like the Raspberry Pi.

For example to connect to a Raspberry Pi just connect the FT232H ground to Raspberry Pi ground, D0 (TX) to Raspberry Pi RX, and D1 (RX) to Raspberry Pi TX like below:

Use PuTTY or screen to open the FT232H serial port at 115200 baud and you'll be accessing the Raspberry Pi's serial port!

You can find more details on accessing a Raspberry Pi through its serial console in this console cable guide.  The FT232H breakout can be used instead of the console cable mentioned in the guide!

This guide was first published on Nov 12, 2014. It was last updated on Nov 12, 2014. This page (Serial UART) was last updated on Sep 20, 2019.