FT232RL USB to TTL Serial Interface Adapter

Provides bridge to connect between TTL serial and a USB port.

DESCRIPTION

The FT232RL USB to TTL Serial Interface Adapter provides a bridge that allows you to connect between TTL serial devices and a USB port.

PACKAGE INCLUDES:

• FT232RL USB to TTL Serial Interface Adapter

KEY FEATURES OF FT232RL USB TO TTL SERIAL INTERFACE ADAPTER:

• Provides bridge between TTL serial communications and USB port
• Mini-B USB connector
• 3.3 or 5V operation is jumper selectable

This adapter is based on the FT232RL chip and provides a bridge for communicating between a typical TTL level serial communication (UART) port as found on many uCs and the USB port normally found on a computer.  This is commonly required when you are programming a new board through its programming interface if it does not have a USB port.

Power

Power for this module come from the USB port.

That USB power is also made available on the header VCC pin for use in powering up the board that the module is plugged into if needed.

The board has a jumper that allows you to select between supplying 5V or 3.3V to this VCC pin. When operating at 5V, the full USB maximum current of around 500 mA is available.  If operating at 3.3V, this power comes from a regulator built into the FT232RL chip and the output is limited to only 50mA.

Module Connections

The module uses a Mini-B style USB connector for connection to the PC.

The Serial TTL interface is brought out to a right angle header.

In addition to the header, the I/O from those pins along with additional I/O from the pins of the FT232RL chip are brought out to  breakout points along the edge of the board. These normally aren’t needed, but do provide easy access points to support atypical applications.  The breakout points also allow straight headers to be soldered in so that the module can be mounted flat on a breadboard if desired.

Hookup is straightforward. The USB end plugs into your computer USB port using a standard USB to mini-B USB cable.

On the TTL side, most applications will just use the RX and TX pins cross-connected between the FT232RL module and your device that you are trying to control.  RX on module goes to TX on device and TX on module goes to RX on device.  There are transmit and receive LEDs on the module that shows activity on these lines.  You will also need to connect the GND pin to ground on the device.

The pin-out of the right angle header is as follows.

1 x 6 Right Angle Header

• DTR =    Data Terminal Ready – an output used for flow control if needed (usually not used)
• RX =      Serial data Receive pin, connects to TX on the device
• TX =      Serial data Transmit pin, connects to RX on the device
• VCC =    Voltage output – controlled by the jumper on the module. If the jumper is set to 5V, this will provide a 5V output at up to 500mA. If the jumper is set to 3.3V, it will provide a 3.3V output at up to 50mA.
• CTS =     Clear To Send – an input used for flow control if needed (usually not used)
• GND =   Ground .  Connect to ground on the device being controlled.

A driver is needed to communicate with the device.  On Windows 10, the driver loaded automatically when the board was plugged in.   If you need to manually download the FT232RL driver, they can be downloaded from the following link:  http://www.ftdichip.com/Drivers/VCP.htm.

Once the driver is properly installed, the device will show up in the Device Manager / USB list as ‘USB Serial Converter’.  It will also show up under Device Manger / Ports (COM & LPT) as a COMx port.  The picture to the right shows how it appears on our Windows 10 setup.  The COM port number which is COM4 here may vary.

OUR EVALUATION RESULTS:

The program below is a simple way to exercise the device and is how we test the modules.

It uses a soft serial port on an Arduino or other MCU to echo commands sent from a computer via a USB port using a terminal program like PuTTY.  Any terminal program will work.  Here is the link to download PuTTY if you need it.

To hook things up connect the FT232RL TX pin to pin 10 (RX) on the Arduino and connect the FT232RL RX pin to pin 11 (TX).  The FT232RL ground pin should also be connected to the Arduino ground.

If you want to also power the Arduino off the FT232RL, ensure that the jumper is set for 5V and connect the VCC pin on the FT232RL to the 5V pin on the Arduino.  There should be no USB cable or external DC power connected to the Arduino if you are using this option.  in our test setup, we are powering the Arduino off the USB cable plugged into it since we are going to be using the Serial Monitor window so VCC is left unconnected.

Ensure a mini-B USB cable is plugged into the FT232RL connector from the computer.

Open the terminal program and set it for 9600 baud and the COM port that the FT232RL shows up on.  In the Putty window below, we are using COM4, but yours may be different.

Open the Serial Monitor window and ensure it is also set for 9600 baud.

Commands typed into the terminal window followed by a carriage return will be sent out the Mini-B USB cable to the FT232RL adapter where it is converted to serial TX/RX data and read through the SoftSerial port on the Arduino.

When the program detects incoming characters on that port, it flashes the LED on the Arduino and sends the character out the USB port where it is displayed in the IDE Serial Monitor window if the Arduino has a USB cable connected.

The command will also be echo’d back through the FT232RL to the terminal program running on the PC and be displayed in the text window.  This simple setup works best when just sending a few characters at a time to avoid overrunning the Arduino buffers.

FT232RL USB to TTL Serial Interface Adapter Test Program

/*
 * FT232RL USB to TTL Test Software
 * This just turns a Arduino into a slave device that will receive characters over
 * a serial interface and echo them back to the sending device as well as print it to
 * the Serial Monitor Window.  It is used to test the FT232RL USB to TTL adapter and 
 * similar devices.
 * 
 * Cross connect the devices TX/RX pins with TX/RX pins defined below.
 * PuTTY serial terminal or similar program is used to send characters to the COMx port.
 * 
 * This uses the SoftSerial.h library which comes with the Arduino IDE
 * Pins used for the soft serial port are fairly arbitrary and can be changed
 * as needed.  Just redefine them below.
 */
#include <SoftwareSerial.h>

const int SSERIAL_RX_PIN = 10;  //Soft Serial Receive pin
const int SSERIAL_TX_PIN = 11;  //Soft Serial Transmit pin
const int LED_PIN = 13;         //On-board LED

// Create Soft Serial Port object and define pins to use
SoftwareSerial TTLSerial(SSERIAL_RX_PIN, SSERIAL_TX_PIN);

int byteSent;
//===============================================================================
//  Initialization
//===============================================================================
void setup() 
{
  Serial.begin(9600);         // Start the built-in hardware serial port
  Serial.println("TTL Serial Echo Test");  
  
  pinMode(LED_PIN, OUTPUT);   // Configure any output pins
    
  TTLSerial.begin(9600);     // Start the soft serial port 
}
//===============================================================================
//  Main
//===============================================================================
void loop() 
{
  // Watch for data coming in on the soft serial port.  If found, send a copy to the 
  // hardware port to display on the local serial monitor terminal and also echo a copy back out 
  // the soft serial port to the sending device  
  if (TTLSerial.available())        // If data has come in from PC
  {
    byteSent = TTLSerial.read();    // Read the byte 
    Serial.write(byteSent);         // Show on local Serial Monitor window
    digitalWrite(LED_PIN, HIGH);    // Show activity on LED
    delay(10);                      
     
    TTLSerial.write(byteSent);      // Echo the byte back to the PC
    digitalWrite(LED_PIN, LOW);     // Turn LED back off
  }  
}

BEFORE THEY ARE SHIPPED, THESE MODULES ARE:

• Sample inspected and tested per incoming shipment.

Notes: 

1. None

TECHNICAL SPECIFICATIONS