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FTDI Cable – USB to RS232 Converter

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FTDI cables are the family of USB to TTL serial UART converter cables and they are incorporated with FT232R IC. The chip handles all the protocol of converting USB data to UART serial data. The cables provide a fast, simple way to connect devices with a TTL level serial interface to USB and they do not require any additional software installation and setting before using them. So they are simple plug and play devices.

 

If stated in a single sentence, we can use FTDI cable to connect RS232 devices to PC.

 

Pin Configuration

As shown in FTDI cable pin diagram, one end of FTDI cable is connected to USB and other end we have six output pins. These six pins are RS232 output. The function of each pin is stated in below table.

Pin

Color

Function

1

Black

GND - Ground

2

Brown

CTS - Clear to Send

3

Red

VCC- Positive Voltage Output (+5V)

4

Orange

TXD- Transmit Asynchronous Data output

5

Yellow

RXD- Receive Asynchronous Data input

6

Green

RTS- Request to Send

 

Features and Electrical Characteristics

  • Data transfer rates from 300 baud to 3Mbaud at TTL levels.
  • Supports RS485 and RS232.
  • Single chip USB to UART conversion.
  • No additional firmware programming required.
  • Receive and Transmit LED drive signals.
  • USB2.0 full speed compatible.
  • Low USB bandwidth consumption.
  • Internal EEPROM with user writable area.
  • Output can be directly connected to microcontroller UART or I/O.
  • Entire USB protocol handled by the electronics in the cable.
  • Integrated power-on-reset circuit.
  • UART signal inversion option.
  • True 5V/3.3V/2.8V/1.8V CMOS drive output and TTL input.
  • Operating temperature range: -40ºC to +85ºC.
  • 128 byte receive buffer and 256 byte transmit buffer, utilizing buffer smoothing technology to allow for high data throughput.
  • Cable length up to 6 feet.
  • FCC and CE compliant.

 

Brief About FTDI cable

FTDI cables are the best option available for interfacing UART devices to the PC. The cable is cheap and easily available in the market. Since no additional firmware installation required for working, the interface can be established at any place and time. Also because of its rigid construction the cable can be used in hard environment. The cable also supports high baud rate for high speed data transfer.

 

How to use the FTDI cable

For understanding the use of FTDI cable let us consider a simple application circuit as shown below.

FTDI cable circuit diagram

In the circuit we have a microcontroller having its UART connected to FTDI cable output. Here TXD of FTDI is connected to RXD of µC and RXD of FTDI is connected to TXD of µC to establish the interface. Now we can directly connect the other end of FTDI to any PC to communicate with the microcontroller. The FTDI cable establishes the handshake between PC and microcontroller so that the microcontroller can be programmed by PC.

 

Applications

  • Upgrading legacy peripherals to USB.
  • USB industrial control.
  • Interfacing MCU/PLD/FPGA based designs to USB.
  • USB wireless modems.
  • USB bar code readers.
  • USB software and hardware encryption dongles.
  • USB flash card reader and writer.
  • USB to RS232/RS422/RS485 converters.

 

2-D Model

FTDI Cable Dimensions