Making a DIY data cable for the Zoop Novo Diving Computer

This is a new version without the need of an Arduino board.
Instead its based on a USB-UART Serial Adapter Module ( FT232RL in this example)

Last year I wanted to get the data out of my Diving Computer without buying $100 cable,
and I succeed doing it by using an Arduino board.
You can read about it here

I was getting lots of comments from people who didn’t succeed building this using other Arduino boards and I thought there must be a way to make it easier.

It just a half duplex (or ‘1 wire’ ) UART , so why it not build a converter from UART to ‘1 Wire’? It should’t be that complicated 🙂

Lets try to make it short

The diving computer has a connector with 2 connection points and a ground.
After poking with it for a ‘few’ hours (I drained all my computer battery and had only 6 dives with it!!) I found that:

  • A voltage on the Enable pin makes the diving computer enter the Data Transfer mode.
  • The Data pin is a bi-directional line, using UART for communication.
  • All the metal around the pins is ‘ground’.

The Suunto DM5 application is looking for a communication port named ‘Suunto USB Serial Port‘.

I used USB to UART Serial Adapter based on the FT232R chip.
Last time I modified the Arduino driver in order to change the device display name,
but after digging I found that Suunto use PID 0xF680 with VID 0x0403 which is the Vendor ID of FTDI chips.
That’s the reason I choose to use the FT232R.

I can still modify the driver, but I have a better option now which is to write to the FT232R eeprom memory and change its PID to 0xF680.
Windows think it’s the Suunto cable and install Suunto drivers with the name we want.
With this method I don’t need to disable the driver signing enforcement.

To modify the eeprom, I used MProg which is a utility from FTDI.

I first scanned for devices on the (Device->Scan), then read the current settings (Tools->Read and Parse), and then change the PID (Product ID) to F680 as you can see in the picture.
I flashed the new settings (Device->Program), uninstalled the current driver in the device manager (right click, Uninstall Device), and removed if from the USB port and then plugged it again.
I don’t know if it’s possible to program it multiple time so it might be irreversible.

Update: It might not be possible to change the PID of a cloned FTDI chip.
In this case, you can still use a modified driver (and disable windows driver signing enforcement), or just use other app like Subsurface which just asks for a COM port number

I can still sync the diving computer without doing this step, but I have to use other apps like ‘Subsurface’.

Because there is only one data line, it was not possible to connect both RX and TX of the UART adapter together as is.
I built a converter circuit with some transistor and resistors to make it ‘1 wire’ half duplex UART.

I used the 3.3V from the USB to UART module.
I also changed the jumper on the module to 3.3V (5V might hard the diving computer)

– 1x USB-UART module (FT232RL)
– 2x 2N7000 NPN transistors
– 2x 1k resistors
– 1x 15k resistor
Jumper cables (optional)
Breadboard (optional)

All can be found in eBay or Aliexpress

If you are using a breadboard you almost don’t need to solder anything.
The only problematic pin is the ’33v’ pin that you have better a jumper cable soldered to.

A command that was sent from the DM5, and a response from the diving computer (the lower voltage signal)

The Ugly Side

I still didn’t find any novel way to connect with this connector.
I took a clamp and drilled holes in it, then pushed ‘pogo pins’ in such a way they will touch the connection points.
I need to think and make something more simple.


First prototype of a PCB version:

And.. that’s it.
I can now sync my diving computer with my PC.

You can find the modified FT232R driver and the MProg config in my gitlab:

14 thoughts on “Making a DIY data cable for the Zoop Novo Diving Computer”

  1. is this new solution much better/safer than your previous pro micro solution? also what wattage resistors do i need?

    i have no experience with this but i want to learn. also i really want the download cable for my zoop novo.
    could i get a pic of what the breadboard should look like?

    Thanks a lot for working on this and releasing the details.

    1. Yes this solution is safer in my opinion.
      You don’t need special resistors, the 1/4W or 1/8W is fine.

      I will try to take some more photos this weekend.

  2. I’ve try it, and its working,
    Cool finally able to download logs from my D9TX, original cable somehow not working anymore.
    Just have not done renaming the PID, need to wait for the original FTDI chip, seem im using the fake one now 🙁 FT prog not working.

    Next wishing someone can recreate the Suunto Eraser app for new models, need to wipeout previous owner logs.. 🙂

    1. Looks like it’s not possible to change the PID in a cloned FTDI chips.
      I tried other modules I have and it didn’t work too.

      Your options are:
      1. get module with a genuine FTDI chip
      2. use the modified drivers (and disable windows driver enforcement)
      3. use other programs like Subsurface which just asks for a com port

  3. for the life of me i cant figure this out… but glad its working for you and others… maybe its the transistor i have, it is called 2N7000 171
    guess ill have to give up but thanks for the info you posted. im just going to sell this suunto and buy something with bluetooth because im so frustrated at this company for charging over $100 for the DL cable and having to go through all this effort.

    1. Does the watch says “Data Transfer”? if not the EN is not connected properly.
      Do you see a bar of dots getting filled when you trying to download data?
      If yes, this means it’s working but it’s not stable. maybe changing the resistors values can solve this.
      If not, again make sure there is a proper connection to the data pin.

      The resistors values are important, don’t change them too much.

  4. stayed up late and got it working! i just tried a few different ways of routing the jumper cables on my board.
    no idea why it was not working before as i think i changed nothing electrically but i don’t really know what i’m doing so could be anything

    thank you very much for helping me.

  5. the PCB looks great, are you still working on this? it would be really cool to release the PCB design so we could take your design and get it created, it would be better then keeping my messy breadboard to get this to work.

    that is of course if the cost of creating a pcb like this with the components would be less than the $100 cable

    1. Thank You!
      The I still have mechanical issues.
      The solution I came up with these pins doesn’t work as expected..
      The PCB is working but it’s not easy to use.

      I need to figure out how to solve this issue.

  6. Hey,
    thanks for this nice article. I have the old Zoop computer with 2 contacts only. but I think the difference should only be, that I need to go into the download menu before manually instead of the EN-Contact.

    Unfortunately this solution does not work for me. I tried it with the Subsurface Program. I think this would be just fine for me. But when I want to download, there is always an error. The USB-UART-Adapter is not from FTDI, but SILabs (CP2102).

    When I download, then the LED for RX and TX seem the blink simultaneously. Is that the same for you when you start downloading?

    I think this should work as well. Do you have any idea, why this would not work? Seems like you had a look on the old plans for the zoop as well… But I think your circuit is much more simple and the old circuits are mainly done for COM-Ports rather than USB.

    1. Hey,
      Yes both LEDs should blink if I remember correctly.

      I would think this is something with the voltage levels are too low and not interpreted correctly,
      or maybe the Pull-up resistors are too strong the TTL signal is warped.

      I found a simple circuit for the old Suunto Vyper, maybe it can work for the Novo

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