How to Use Adafruit FTDI Friend: Examples, Pinouts, and Specs

The Adafruit FTDI Friend is a versatile, compact USB to serial converter based on the FT232RL chip from FTDI. This component is essential for interfacing microcontrollers and other serial devices with a computer, enabling programming, debugging, and serial communication through a USB port. It is particularly useful for devices that do not have a built-in USB-to-serial converter, such as older Arduino boards or custom microcontroller projects.

• Programming microcontrollers without onboard USB-to-serial conversion
• Debugging and serial communication with microcontrollers
• General USB to RS232 conversion for legacy devices
• Bridging a USB connection to TTL serial devices

• Chipset: FT232RL
• Operating Voltage: 5V (VCCIO is set to 5V)
• I/O Logic Level: 3.3V or 5V (selectable via solder jumper)
• USB Standard: USB 2.0 Full Speed
• Max Data Rate: 3 Mbps
• Connectivity: Mini-B USB connector
• Dimensions: 1.8" x 0.6" x 0.2" (45.7mm x 15.2mm x 5mm)

1. Connecting to a Microcontroller:

   • Connect the FTDI Friend's TX pin to the microcontroller's RX pin.
   • Connect the FTDI Friend's RX pin to the microcontroller's TX pin.
   • Ensure that the GND pin is connected to the microcontroller's ground.
   • Optionally, connect the DTR pin to the microcontroller's reset pin through a 0.1uF capacitor to enable auto-reset for programming.

2. Powering the Device:

   • The FTDI Friend can be powered directly from the USB connection.
   • Ensure that the VCC pin is connected if the microcontroller requires 5V power from the FTDI Friend.

3. Logic Level Selection:

   • The default I/O logic level is 5V, but it can be changed to 3.3V by adjusting the onboard solder jumper.

• Always verify the logic level compatibility of the FTDI Friend with the target device to prevent damage.
• Use proper ESD precautions when handling the FTDI Friend to avoid static damage to the chip.
• When using the DTR pin for auto-reset, ensure the capacitor is correctly placed to avoid incorrect reset behavior.

• Device not recognized by the computer:

  • Check the USB cable and connections.
  • Ensure that the correct drivers are installed for the FT232RL chip.

• No communication with the microcontroller:

  • Verify that the TX and RX pins are not swapped.
  • Check the logic level settings and ensure compatibility.

• Microcontroller not auto-resetting:

  • Ensure the DTR pin is connected through a 0.1uF capacitor to the reset pin of the microcontroller.

• If the device is not recognized, download and install the latest FTDI drivers from the FTDI website.
• Use a multimeter to check for continuity and correct voltage levels on the pins.
• For auto-reset issues, check the polarity and value of the capacitor connected to the DTR pin.

Q: Can the FTDI Friend be used with 3.3V devices? A: Yes, the logic level can be set to 3.3V by adjusting the onboard solder jumper.

Q: Does the FTDI Friend come with a USB cable? A: No, a USB Mini-B cable must be purchased separately.

Q: How can I change the serial baud rate? A: The baud rate can be set through the serial communication software on your computer, such as the Arduino IDE's Serial Monitor.

// This example demonstrates basic serial communication between the FTDI Friend
// and an Arduino UNO. The Arduino will echo any received characters.

void setup() {
  // Start the serial communication with a baud rate of 9600
  Serial.begin(9600);
}

void loop() {
  // Check if data is available to read
  if (Serial.available() > 0) {
    // Read the incoming byte
    char incomingByte = Serial.read();
    
    // Echo the incoming byte back to the serial port
    Serial.write(incomingByte);
  }
}

Remember to select the correct COM port and board configuration when uploading code to the Arduino using the FTDI Friend.