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Description: Introducing the 3.3V FT231X Breakout board, complete with the full UART hardware handshake feature! The pinout of this board matches the FTDI cable to work with official Arduino and cloned 3.3V Arduino boards. It can also be used for general serial applications. This board still brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded. This is a really nice feature to have and allows a sketch to be downloaded without having to hit the reset button. This board will auto reset any Arduino board that has the reset pin brought out to a 6-pin connector.

The coolest thing about the FT231X Breakout is that we have broken out ALL the pins for your use, making this board all the more hackable! 

One of the features of this board is a jumper on the back, which allows the VCC output to be configured to either 3.3V or 5V. This board ships default to 5V, but you can cut the default trace and add a solder jumper if you need to switch to 3.3V. It should be noted, however, that the max input of the FT231X is only 3.3V but it can operate down to 1.8V with external pull ups and is also 5V tolerant.


Comments 18 comments

  • Has anybody used this board to program a Picaxe?

    • I have used the FT232R breakout to program the Picaxe. The trick there was to invert the lines using FT_Prog (

  • Can I use this board for 1.8v UART?
    I want to read the serial console output from an ODROID board, which uses 1.8V. If so, can anyone explain how?

  • It would be nice if these boards actually came with a header for a real jumper rather than solder traces/bridges. I’m lazy and when I need to switch from 3.3v to 5v, I’m not really looking forward to the extra work of solder/desolder to get what I want. ;-) It only requires about 0.4 inches of board real estate (well, you could use smaller headers too, I suppose) and I’m even willing to take the time to install the header myself.

    My other FT232 boards are voltage selectable via some wire-wrap connections, but that can be error prone if you’re not double-checking your work.

  • So can this program both 3.3V and 5V arduino pro mini?

    • Yup. The output voltage of this board is selectable between 3.3V and 5V. The output logic levels will always be 3.3V (5V input tolerant though), which’ll work for a 5V pro mini too.

      To select the VCC and DTR output voltage, there’s a 2-way jumper on the backside (three bare solder pads, next to the ’s'). By default it comes shipped set to 5V. To set it to 3.3V, cut the tiny jumper between the 5V and middle pads, and then make a solder blob to connect the 3.3V and middle pads.

      • The product description indicates that it ships 3.3v by default. Is that correct?

        Also are dtr and vcc only broken out on the front? Looking at this for use on a breadboard and it looks like you’d have to pick the front or sides for headers.

        Thanks, Karl

        • Shoot…that’s not correct. I fixed the description, thanks for catching it.

          DTR is only broken out on the header opposite the USB connector. But it’s on the corner, so it’ll also work with the rest of the side headers. VCC’s only on the 6-pin header too, but both 3.3V and 5V are broken out on the side headers. You should have access to everything if you want to breadboard it.

          • Thanks! One more question. Based on the description, are all pins other than VCC and 5V operating at 3.3v levels? If so, if I only use the 3.3v pin for power and never go near VCC/5V is there any reason for me to cut the trace to use this as a 3.3v board?

            • If you need DTR at 3.3V, you’ll still want to cut/jump the trace. DTR’s got a level-shifting circuit on it, and it’ll shift the to whatever VCC is set to on the jumper. (Had to boost it because the reset pin on an Arduino is pretty restrictive on what it counts as a logic high – 3.3V wouldn’t cut it if the micro was running at 5V).

  • The Eagle Files are linked to the gerber files.

  • I agree with Member #156731 about not wanting to purchase Sparkfun boards with Micro USB connectors. Of the many Micro USB connected boards I’ve bought from Sparkfun, only one still has the Micro USB port still attached however it’s partially separated and I was able to catch it in time to add a couple drops of Super Glue to reattach the base feet to the board.

    • I certainly understand the concern about the micro connectors ripping off. It’s the way the connectors are trending, though; and it keeps the board smaller.

      We are continuing to revise both our PCB footprint and the assembly/testing process for these. Check out this board’s Eagle files for our most recent version of the fp. We added a couple solder pads under the connector to help strengthen the connection, and it’s been working really well. Really have to try to rip the connector off now. That said, it still doesn’t hurt to be gentle, or hold a thumb on the connector, when disconnecting the cable :).

      • If you would add a couple of thin slots on either side of the connector, a user could add a Zip-Tie, which could then be placed around the connector and thru to the back of the board and give it a fair bit of mechanical strength. You would have to move the vias that are on either side, near the back of the connector as that is where the slot would go.

        Virtually zero cost to add, other than the slight bump on the PC fab costing for the extra holes.

        • As long as the SMD pads are reinforced with, decently sized, vias, the most your should need is a little extra solder.

      • There is an incredibly large range of options available for micro USB connectors, and the Sparkfun’s choice in this case is well known for being the weakest and highly prone to failure.

        As this is a hobby product that is definitely going to get a lot more use and abuse than your average consumer product, I would expect a company like Sparkfun to make a more suitable choice. It’s just not rocket science.

        A very simple and easy step forward towards a more robust product is to use a connector which is exactly the same as the one you’re using except with shell through hole mounts. The cost of the connector is virtually identical. Obviously it adds a through hole step to your production process, but if that adds an extra dollar or two to the product cost then so be it. I certainly won’t complain.

      • I’ve been using mid-mount micro USB connectors recently:

        They’re pretty tough! Of course they do take a tad bit more board area

  • Nice board but seams to have a micro usb connector. Not my favorite flavour…

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