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TTL-232R USB - TTL Level Serial Converter

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Vendor's Description: 

TTL serial converter cable which will allow for a simple way to connect serial TTL level devices to USB. No MAX232 or other level converters needed. It works very well with Atmel based controllers.  In my own designs, I always include a connector for the TTL-232R.

Pinout 0.1" pitch header socket:

  1. GND - Black
  2. CTS - Brown
  3. VCC - Red
  4. TXD - Orange
  5. RXD - Yellow
  6. RTS - Green

The TTL-232R uses a FT232RQ chip which is housed within the USB "A" connector. A 1.8 meter (6 foot) cable is terminated with a 6 way 0.1" pitch header socket which provides access to the Transmit (Tx), Receive (Rx), RTS#, and CTS#, as well as VCC (5V) and GND.

Several variants of the TTL-232R are available:

  • TTL-232R-3V3 (TTL-232R with 3.3V IOs)
  • TTL-232R-AJ (Audio Jack connector, 5V IOs)
  • TTL-232R-3V3-AJ (Audio Jack connector, 3.3V IOs)
  • TTL-232R-PCB (Populated PCB from the TTL-232R USB connector, 5V IOs)
  • TTL-232R-3V3-PCB (Populated PCB from the TTL-232R-3V3 USB connector, 3V3 IOs)
  • TTL-232R-WE (No connector at serial end, 5V IOs)
  • TTL-232R-3V3-WE (No connector at serial end, 3.3V IOs)


  • TTL-232R Converter Cable provides a USB to TTL Serial header interface (6 way, 0.1” pitch).
  • On-board FT232RQ provides single chip USB to asynchronous serial data transfer interface.
  • Entire USB protocol handled on the FT232RQ chip - No USB-specific firmware programming required.
  • Connect a microcontroller/PLD/FPGA directly to a PC USB port.
  • Fully compatible with existing legacy COM port software.
  • FTDI’s royalty-free VCP drivers allow for communication as a standard COM port and D2XX ‘direct’ drivers provide DLL application programming interface.
  • Data transfer rates from 300 Baud to 3 Mega Baud at TTL levels.
  • UART interface support for 7 or 8 data bits, 1 or 2 stop bits and odd/even/mark/space/ no parity.
  • Fully assisted hardware (RTS#/CTS#) or X-On/X-Off software handshaking.
  • 5V CMOS drive outputs and 5V safe TTL inputs makes the TTL-232R easy to interface to 5V MCUs.
  • Support for FT232R FTDIChip-ID™ feature.
  • Cable supply voltage comes from USB - no external supply required.
  • 5V output allow devices to be powered from the USB port.
  • 6 way 0.1” header connector (Tx, Rx, RTS#, CTS#, VCC, and GND).
  • Low USB bandwidth consumption.
  • HCI/OHCI/EHCI host controller compatible.
  • USB 2.0 Full Speed compatible.
  • -40°C to +85°C operating temperature range.
  • Connect to a PC via USB ‘A’ plug on 1.80 meter (6 foot) cable.
  •  3.3V TTL I/O version is also available (TTL-232R-3V3)
  • Custom versions also available (subject to MOQ).


The TTL-232R is competitively priced at $20 each in small quantities.  It is available on-line from the FTDI Chip Shop, or through the FTDI worldwide sales network.

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FWIW, all my Linux machines have worked with this cable out of the box, no driver installations needed. My XP machines seemed to have the driver installed when the Arduino IDE was installed, as I never had to manually install a driver. YMMV

Other things to think about when choosing which variant you want; the 3.3V cable still puts the standard USB 5V out of it's power line. The 3v3 version also communicates well with 5V AVRs though, I use the 3v3 with my pseuduino all the time and it works fine, but the same cable still works great with my Propeller and my RSMedia (which are both 3.3V systems) without cooking anything.

I don´t know wich version is my cable  :D
Okay thank you!
I got a question. Let's say I want to use this cable for my standalone arduino board. I want to program the standalone arduino board using the cable. Which pin do I connect to the reset pin of the board? Do I use CTS or RTS?
I use this cables a lot with my custom arduino's. If you want to reset the arduino before uploading you should connect the RTS (green) to a 0.01uF cap, and then to the reset pin.  ;)

Did you make some special configuration for the COM port to get this working. Maybe it's just a side effect that RTS will be pulled down when opening the COM Port.

OK, I found something:

The Arduino Blog entry for modifiing Arduino NG boards. Here DTR is used.

Modern Devices made their Barebone Boards Auto-Reset enabled with the following COM Port changes. They use the FTDI TTL-232R cable and a capacitor between RTS and RESET.

You will need to set a parameter with your serial port to get the serial port to produce the required signal.
Device Manager -> Com Ports -> USB Serial Port -> Port Settings -> Advanced button -> Set RTS On Close

So it seems to work. I will try this on my selfmade boards. Thank you guibot :-)


I didn't know you need to do that configuration in Windows, in Mac is "plug-and-play"  :)
For the auto-reset feature DTR is used on the Arduino Boards. So using RTS or CTS will not work. Maybe it is possible to change the sourcecode for the Arduino flasher and recompile it, but I'm not shure.

USB cables are very handy, but you must have the correct driver for your system.

For PICAXE users, the "standard" USB cable  (as for an Arduno) does not work.

PICAXEs requires inverted signals. Fortunately you can ldownload a FTDI programmer at no charge from their website to correct this.


I don't know much about PICAXEs and didn't find the program (programmer?). Can you post a link or description, so I can correct the article?