USB to TTL Card (FTDI-USB-TTL)

The FTDI USB to TTL Board allows a computer with a USB port to talk to devices (like Arduino derivatives) which have TTL-level (3.3/5V) serial ports.

Features

The FTDI USB to TTL Board Revision X6 is a substantial departure from previous versions of the FTDI USB-to-TTL boards. Some of the differences include:

  • Different FTDI chip (FT230X instead of the FT232RL).
  • The FT230X[1] is less expensive ($2.04 at Mouser for a single piece) than the FT232RL[2] ($4.50 at Mouser for a single piece).
    • Smaller form factor.
      • Still 1" wide but narrower.
      • 1" wide due to 4-40 hardware and USB connector.
      • Less expensive PWB (Under $1.10 a board from OSHPark).
  • Moved the connectors (USB and otherwise) to the back side of the board. 
    • So the back is like the front except that the chip is on the other side of the board from the connector.
    • Moved the USB connector closer to the edge of the card.
      • This will help the connector stick through the side of the enclosure it is in more easily.
  • Set VCCIO to 3.3V so that the board can work with 3.3V or 5V interface cards.
  • 3.3V or 5V input tolerant.
  • Board revision X5 had wrong pinout for the FTDI chip (QFN pinout instead of SO-16).
    • Rev X6 fixes that.
  • USB shell ground is no longer connected to the board ground.
    • Assuming that the USB cable is shielded (they are).
    • Assuming that the USB shield connects to the metal shell of the connector on both ends (they do). 
    • Assuming that the USB cable doesn't connect the wire ground pin to the shield (they don't).
    • Don't know if this matters in plastic cases, but for metal cases it might matter since it will keep the grounds of the chassis isolated.
  • Handshake signals different but still work with Arduino IDE.
    • Uses RTS/CTS instead of DTR/CTS.
  • Pin 1's are marked with a white dot on the silkscreen.

Other important features include:

  • 4-40 mounting holes on both sides of USB connector for sturdy mount.
  • 3.3V/5V Header selects the voltage that will be provided from the FTDI USB to TTL Board.
    • Note that the 3.3V has serious current limitations since the FT230X provides the voltage regulation.
    • If the jumper is left off the header the board can provide its own power.
  • 6-pin connector matches http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm FTDI pinout for TTL connector</a>.
  • Transmit and Receive LED connector with current limiting resistor on-board.
  • 5V tolerant inputs.

Technical Documents

Detailed technical documents are here.