How to Use USB-TTL: Examples, Pinouts, and Specs

The USB-TTL converter, manufactured by Prolific, is a versatile electronic component designed to facilitate serial communication between a USB port and devices operating at TTL (Transistor-Transistor Logic) voltage levels. This component is widely used for programming microcontrollers, debugging embedded systems, and interfacing with various electronic modules such as sensors, displays, and communication devices.

• Programming microcontrollers (e.g., Arduino, ESP8266, ESP32, etc.)
• Debugging and monitoring serial data from embedded systems
• Interfacing with TTL-level devices such as GPS modules, GSM modules, and sensors
• Creating custom USB-to-serial communication tools
• Prototyping and testing serial communication protocols

The Prolific USB-TTL converter is designed to provide reliable and efficient communication between USB and TTL devices. Below are the key technical details:

• Manufacturer: Prolific
• Model: USB-TTL Converter
• USB Standard: USB 2.0 (compatible with USB 1.1 and USB 3.0)
• Supported Baud Rates: 75 bps to 12 Mbps
• TTL Voltage Levels: 3.3V and 5V (selectable)
• Operating Temperature: -40°C to 85°C
• Driver Support: Windows, macOS, Linux

The USB-TTL converter typically features a 6-pin header for TTL communication. Below is the pinout and description:

Note: Some USB-TTL converters may omit RTS and CTS pins if hardware flow control is not supported.

1. Connect the USB-TTL to Your Computer:

   • Plug the USB-TTL converter into an available USB port on your computer.
   • Install the required Prolific drivers (if not already installed). These can be downloaded from the Prolific website.

2. Connect the TTL Device:

   • Use jumper wires to connect the USB-TTL pins to the corresponding pins on your TTL device:
     • GND: Connect to the ground pin of the TTL device.
     • TXD: Connect to the RX (receive) pin of the TTL device.
     • RXD: Connect to the TX (transmit) pin of the TTL device.
     • VCC: Connect to the power input of the TTL device (ensure the voltage matches the device's requirements).

3. Select Voltage Level:

   • If your USB-TTL converter has a voltage selection jumper, set it to 3.3V or 5V based on the TTL device's operating voltage.

4. Open a Serial Communication Tool:

   • Use a serial terminal program (e.g., PuTTY, Tera Term, or Arduino IDE Serial Monitor) to communicate with the TTL device.
   • Configure the baud rate and other serial settings to match the TTL device's requirements.

• Voltage Compatibility: Ensure the voltage level (3.3V or 5V) of the USB-TTL converter matches the TTL device to avoid damage.
• Cross-Connection of TX and RX: Always connect the TXD pin of the USB-TTL to the RX pin of the TTL device, and vice versa.
• Driver Installation: Verify that the Prolific driver is correctly installed on your computer. Without the driver, the USB-TTL may not be recognized.
• Avoid Overloading: Do not draw excessive current from the VCC pin of the USB-TTL converter. Check the datasheet for the maximum current rating.

The USB-TTL converter can be used to program or communicate with an Arduino UNO. Below is an example of how to use it with the Arduino IDE:

// Example: Sending data from Arduino to a computer via USB-TTL
// Open the Serial Monitor to view the output.

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
}

void loop() {
  Serial.println("Hello from Arduino!"); // Send a message to the computer
  delay(1000); // Wait for 1 second
}

Note: Disconnect the USB-TTL converter from the Arduino UNO while uploading new sketches to avoid conflicts with the onboard USB interface.

1. USB-TTL Not Recognized by Computer:

   • Ensure the Prolific driver is installed and up to date.
   • Try a different USB port or cable.
   • Check the device manager (Windows) or system profiler (macOS) to verify the USB-TTL is detected.

2. No Data Transmission:

   • Verify the TXD and RXD connections are correctly crossed.
   • Check the baud rate and serial settings in your terminal program.
   • Ensure the TTL device is powered and functioning.

3. Incorrect Voltage Level:

   • Double-check the voltage selection jumper on the USB-TTL converter.
   • Ensure the TTL device operates at the selected voltage (3.3V or 5V).

4. Data Corruption or Noise:

   • Use shorter, high-quality jumper wires to reduce interference.
   • Ensure a common ground connection between the USB-TTL and the TTL device.

Q: Can I use the USB-TTL converter to power my TTL device?
A: Yes, but ensure the current draw of the TTL device does not exceed the USB-TTL converter's maximum output current (typically 50-100mA).

Q: Is the USB-TTL converter compatible with 1.8V devices?
A: No, the USB-TTL converter supports only 3.3V and 5V logic levels. Use a level shifter for 1.8V devices.

Q: How do I check if the Prolific driver is installed?
A: On Windows, open the Device Manager and look for "Prolific USB-to-Serial Comm Port" under Ports (COM & LPT). On macOS or Linux, use the lsusb command to list connected USB devices.

Q: Can I use the USB-TTL converter with Raspberry Pi?
A: Yes, the USB-TTL converter can be used to establish a serial connection with the Raspberry Pi's GPIO UART pins. Ensure proper voltage levels and connections.

By following this documentation, you can effectively use the Prolific USB-TTL converter for a wide range of serial communication applications.