The FTDI adapter



The 6 pin header next to the antenna connector is the serial connector, which allows communication between the ULRS and the computer or tablet.

This connector is sometimes referred to as the FTDI header, in reference to the FTDI company who is one of the main manufacturer of USB-to-serial chips and adapters.


Where to order an FTDI adapter

  • Please use only genuine FTDI adapter : link to order page
  • Be careful to choose the 3.3V version (follow the link above).
  • The first advantage is that the electronics in hidden in the USB connector :


  • The second advantage is that it works. It’s really worth the cost of using a genuine FTDI cable, as I’ve seen several clones giving many issues. For example flashing the firmware will work every three times.
  • The core issue is that the atmega isn’t able to give a precise 115200 bauds serial, and gives something close but higher like 117000 bauds. This works with genuine FTDI adapters, but not with all clones.


How to connect RX and TX

There’s sometimes a confusion, because the TX pin of the ULRS must be connected to the RX of the FTDI, and vice-versa. This is normal, for serial connection the RX pin of anything has to be connected on the TX pin of something else.

But to make it clear, you must connect the FTDI adapter pin to pin to the OrangeRX serial connector, without any crossing cable. The Wolfbox modules do have a different pinout, which is described here.

Alternative color code

Some FTDI use an alternative color code described below :

The DTR or RTS signal

Notice the important pin marked DTR on the ULRS : this is used during programming, and causes a reset that will put the module in bootloader mode.

On the alternative color FTDI cable described above, use the RTS signal in place of the DTR signal (which isn’t available).

The CTS signal

The CTS pin is not needed for ULRS.

Flashing a Wolfbox 1W module

The Wolfbox modules have a non-standard connector for FTDI.

Be careful to connect the correct pins (DTR, RX, TX, GND), taking care of crossing the RX and TX as usual.


  1. fpv_duck says:

    So I tried to “cheap out” and bought this cable (DO NOT BUY) but it didn’t work.

    Then I cheaped out again, mainly because paying 50 bucks for a cable didn’t sound right, and I got it working using this adapter:

    I’ve just flashed 2 orangerx, so I can’t say if it works 100% of the time, but at least I could get it to work.

    • admin says:

      Hello, the quality of the FTDI cable is important and not all are working well. Some cheap cables will work and some won’t. Thanks for the link you provided, it will be useful for other users.

  2. says:

    Sure, like the well-known FTDI cable, it can provide power to your project and there are 4 signal lines for sending data back and forth.

  3. JAIMIN says:


  4. andy says:

    Is this the correct FTDI cable?

    • admin says:

      That one doesn’t work very well, I’d recommend to stick with the genuine FTDI cables, see the link on this page.

  5. RMAU says:

    Does the driver for this work with Windows 8.1? My old cable didn t work with my new laptop.

    • admin says:

      Hello, you’ve got to install the driver provided with your FTDI cable, or you can try the official drivers from the FTDI site. I’m using Windows 8.1 without issues, but with a ‘real’ FTDI cable.

  6. Creotom says:

    Hi I have flashed two units using the cable mentioned above, TTL-232R-3V3.
    It is described as a 3.3v cable but now that I read it again I see that it has 5v on the vcc.

    Have I damaged the devices do you think?

    • admin says:

      The 1W modules are usually quite resistant to this (in comparison the 100 mW would be killed instantly as they are 3.6V devices).

  7. csomyy says:

    I’d like to use Ultimate LRS on an Adnroid tablet, with Tower on USB, with FTDI.

    The problem is, that Tower wants to connect on USB on baud 57600 and there is no way to change it.
    ULRS uses 115200. Is there a way to modify the connection speed, or any other solution?

  8. admin says:

    You can either power via the FTDI VCC pin, or via the VCC pin of the OrangeRX module.

    The only risk is to apply 5V of the FTDI VCC pin of the 100mW board, as it will fry the RF module (RFM22B). Normally the 1W module can handle 5V (RFM23BP).

    To avoid all risks, I prefer to recommend always powering via the VCC (non-FTDI) pin, which will work for all modules.

  9. Hugues says:

    In the FTDI instructions you say that, I quote : “VCC : do not connect, (will not cause big trouble, but OLRS has its own 3.3V regulator)”. Then how is the OrangeRX module powered during the flashing process ?
    In my case I connected the VCC at 3,3V (not5V) and it all works fine.
    It would be useful top adapt this instructions page by giving the whole wiring scheme including the powering part, if needed.

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