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)

BOM:
– 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.

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.

Another option:

MudiStar has made a 3D design of a plug to the Zoop Novo.
You can use a 3D printer to print it, or a 3D printing service.
More info can be found here: https://www.thingiverse.com/thing:5184406

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:
https://gitlab.com/itaysp/suunto-data-cable

Update 11/01/2020: New post with an updated version without an Arduino board can be found here

Update 09/01/2020: I found it easier to use ESP32 and get it working. You also don’t need resistors and it’s safer to use because the ESP32 working voltage is 3.3V.
The process is the same, the connections are different.
I used the Lolin32 Lite (which has a CH430 USB-SERIAL).
Modified drivers for the CH430 and connection diagram can be found on my gitlab.

Few months ago, I went diving and decided it’s time to get a my first diving computer.
A little research and I came into conclusion that the Suunto Zoop Novo is what I should buy.
It’s cheap (around $200 in Eilat, Israel), and have many positive reviews.

This diving computer has an option to sync it with your PC and watch the diving logs in Suunto DM5 app (or other open source apps), but unfortunately it sold without the data sync cable 🙁

If you wish to get an official cable from Suunto, you will have to pay around $84 on Amazon ! (with shipping it’s $100 to Israel )

A little googling and I found many DIY cables, but for the old generation of the Zoop Novo.

How hard can it be to make this diving computer to talk with my PC?
Well, not so hard if don’t care using other apps for syncing ,
and a little harder if you wish to use Suunto DM5 app.

Lets try to make it short

I will write in more details when I’ll have time (it took me 3 months to write this post :S)

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 an Arduino Pro Micro, which has build in USB functions and can act as USB Serial COM device, and had to change the driver so it’s name will be ‘Suunto USB Serial Port’. It’s very easy but require to disable driving signing enforcement .

I can still sync the diving computer without doing this, 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 Arduino’s UART together as is.
I used the Arduino’s hardware UART to read the data from the diving computer, and used Software Serial to write to the diving computer. When not reading – I changed the TX line gpio to ‘Input Pullup’ so it’s won’t interfere with the reading operation.

I used the 5V from the Arduino pins. I didn’t know it’s safe to use 5V here, so I used 330ohm resistors in series with for the ENABLE and the TX of the DATA. I found this value gives about 3.2V, but maybe using a higher value will work too and it will be even safer.

How it works:

DM5 app is sending data for the Diving Computer in a COM port called ‘Suunto Diving computer’, but it’s actually sending this data to the Arduino.
The Arduino receives is in it’s default serial that is connected to the usb, and forward it to the Diving Computer using SoftwareSerial on gpio 8.
When the DM5 app is not sending anymore data, the Arduino change gpio 8 to “Input Pullup”, and starts reading data from ‘Serial1’ (this is HW serial), and forward is on ‘Serial’ (which is connected thru USB to the computer)

Arduino Code

#include <SoftwareSerial.h>
#define SW_TX 8

SoftwareSerial mySerial(4, SW_TX); // RX, TX

void setup(){
  Serial.begin(115200);     // Between computer and Arduino
  Serial1.begin(115200);    // Between Arduino and Diving Computer
  mySerial.begin(115200);   // Between Arduino and Diving Computer
  
    while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  pinMode(SW_TX,INPUT_PULLUP);
}

void loop(){
  if(Serial.available() > 0) {
    pinMode(SW_TX,OUTPUT);  
    digitalWrite(SW_TX,HIGH); //UART lines should be HIGH on IDLE
  
      while(Serial.available()  > 0){
        mySerial.write(Serial.read());
      }
    pinMode(SW_TX,INPUT_PULLUP);
  }
  
  while(Serial1.available() > 0){
    Serial.write(Serial1.read());
  }
}

The Ugly Side

I 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.

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

You can find the modified .inf file and the code in my gitlab:
https://gitlab.com/itaysp/suunto-data-cable

And you can download the full driver from Sparkfun’s website (just use my .inf file)