Easy to Build Oxygen Analyzer Using an Arduino Compatible Micro Controller


87,776

97

38

Introduction: Easy to Build Oxygen Analyzer Using an Arduino Compatible Micro Controller

As a builder of gadgets and a scuba diver I have been trying to build an oxygen analyzer for a bit now. The big problem is that most micro controllers can’t read the mv that the sensor puts out. I played with opamps, but never got it to work properly. Finally I found the Texas Instruments ads1015, an analog to digital convertor chip “adc”. Adafruit makes a nice breakout board to make your life easier.

Now I only need a micro controller, an LCD screen, an oxygen sensor, a push buttons and like 9 resistors or so and I got yourself an oxygen analyzer.

Step 1: Shopping List

Below are the components and parts with the links to where you can buy them

Step 2: Connecting It All Together

ADS1015

VDD Pin to 3.3v

GRD Pin to Ground

SCL Pin to A5 Pro Trinket

SDA Pin to A4 Pro Trinket

A0 Pin to Connected to the Audio Jack - O2 Sensor + pole

A1 Pin to Pull up Resistor 10K

A2 Pin to Pull up Resistor 10K

A3 Pin to Pull up Resistor 10K

Nokia display

VCC Pin to 3.3v

GRD Pin to Ground

SCE Pin to D8 Pro Trinket

RST Pin to D6 Pro Trinket

D/C Pin to D5 Pro Trinket

DN(MOSI) Pin to D11 Pro Trinket

SCLK Pin to D13 Pro Trinket

LED Pin to 200 ohm resistor to 3.3 V

Push Button

1 pin to Ground

2 Pin to D3 and a 10k pull-up resistor to 3.3v

Lipo Backpack

G Pin to Grd on Pro Trinket

3V 3V Pro Trinket

Pro Trinket

All the connections to the pro trinket are described in the above descriptions. I have added one 10k ohm pullup resistor to the RX pin. The Pro Trinket has the habit to sometimes hang on boot. This pullup resistor seems to remedy this. Why?..... Don’t know, a much smarter tinkerer on one of the Adfruit forums told me this piece of wisdom.

Note

The Lipo Backpack is the power source for the project. Every 3v connection needs to be connected to the Lip Backpack 3v and all the Ground connections need to be connected to the Lipo Backpack Ground including the audio jack witch is connected to the Ground of the Oxygen Sensor.

Step 3: The Code

All the libraries used are from Adafruit and are easy to download from their site at www.adafruit.com. The formula for calculation the O2 % is simple.

(current mv from sensor / mv from sensor in the air) *20.9.

The only thing you need to do is store the "mv from sensor in the air" value in a variable before you try to analyze any gas. I do this in setup routine of my sketch or when you press the push button. Just download this zip file and upload the sketch to your pro trinket.

Step 4: Finishing Toughes

To complete the project I put all the components in an enclosure and added 5v Regulator like a the 7805T witch I connected to the 5V in pin and the ground pin on the Lipo backpack to charge the battery.

I also added some code to calculate the maximum operating depth “mod” of the analyzed gas for a PO2 of 1.4,1.5, and 1.6

Formula for Imperial “Feet”

mod= ((po2/fraction of gass)-1)*33

Formula for Metric “Meter”

mod= ((po2/fraction of gas)-1)*10;

I also added a button so I could create a menu to select your mod unit “Meter or Feet”. To prolong the battery life I made it so that you can turn the backlight on the LCD display on and off.

I could show you how to do these things but figuring this stuff out is half the fun. If you get stuck I can help a little. If you know how to improve on the project please let me know as it is always good to learn new things.

Be the First to Share

    Recommendations

    • Chocolate Challenge

      Chocolate Challenge
    • Electronics Contest

      Electronics Contest
    • Stone Concrete Cement Contest

      Stone Concrete Cement Contest

    38 Comments

    0
    Yatan Jain 200
    Yatan Jain 200

    1 year ago on Step 4

    I am from India don’t have time to built oxygen analyser as I am making oxygen concentrator, which are in very poor supply and need oxygen analyser to check the efficacy of my product. I had enquired lot of Dealers and Distributer but due to Pandemic no one is having one and due the same imports are also very very restricted. So if someone has made kindly send the video of the product on my Whatapp no. 9717104999, I will wire the amount but the courier service should be DHL or FedEx. Pls support in this difficult times. Or if some one can source the envitec Oxyquant S and send .
    Yatan Jain

    0
    joker14115
    joker14115

    1 year ago

    hello dear
    i cant under stand ur sketch
    it seems not complete and is for just callibrating sensor,
    how do u know what percentage is o2 with current mv of sensor
    it must be a function

    0
    constbad
    constbad

    1 year ago

    Please mention If someone did this instrument. How much it costs ? The links with sensor îs not more available . Could You mention other links ? Thanks.
    If somebody knows a similar circuit for oxigen monitorizing please mention it here or on email : constbad@gmail.com. thanks

    0
    surojit191
    surojit191

    Question 1 year ago

    CAN I GET SINGLE LINE CIRCUIT DIAGRAM OF THE ABOVE PROJECT

    0
    jrgonaut
    jrgonaut

    Question 1 year ago

    Hi! Can I turn this into a controller as well?

    0
    rajesh197219
    rajesh197219

    Question 2 years ago on Step 2

    can you send the circuit diagram and some fundamental calculation

    0
    SaeidD1
    SaeidD1

    2 years ago on Step 3

    Thank you for your training
    Does this sensor show up to 98%?

    0
    sivaramteerth
    sivaramteerth

    Question 2 years ago

    What is the accuracy limit of the oxygen sensor used in this analyzer?
    Can it detect the oxygen within a limit of 0.1 - 0.5%?

    0
    CrumpittRN
    CrumpittRN

    Question 2 years ago on Introduction

    Hi, could this be turned in to a trimix analyzer? Used to Show both 02 and He maybe even the MOD of the mix?
    Thanks

    0
    TiếnB1
    TiếnB1

    5 years ago

    Hi, Can it measure the oxygen in the air like in the room???

    I want to buid it to measure the oxygen in the factory...

    0
    viola2572
    viola2572

    Reply 3 years ago

    yes it can

    0
    VeetuM
    VeetuM

    Question 4 years ago on Introduction

    Hi.

    i wanted to findout if you had a circuit diagram of the oxygen anlyser you worked On ,i really wanted to see the arrangements.

    THANKS!

    0
    GBhargavi
    GBhargavi

    4 years ago

    Can O2 sensor measures the oxygen in air?
    Actually,I want to use this sensor to measure the oxygen in hill areas.is this possible or not?

    0
    um96
    um96

    4 years ago

    mine is not working i have used an arduino uno and my sensor is envitech oom 102-1 but the display just gives the output calibrating nothing else .

    please help me

    0
    HaliffR
    HaliffR

    5 years ago

    i want to connect this to piezoelectric valve. the purpose is to keep oxygen at 5% in a small space close environment of biological organism. is it just simple modification of your code? Can someone point me the right direction? thanks!

    0
    CJR8
    CJR8

    5 years ago

    Hi! Does this reads water oxygen level?

    0
    akurk
    akurk

    Reply 5 years ago

    No it does not, it is a gas analyzer. I am not even sure if there is a probe or sensor that reads dissolved O2 in a liquid .

    0
    ptschram
    ptschram

    Reply 5 years ago

    Dissolved oxygen is one of the most common wastewater analyses conducted. Multiple vendors provide ion-specific electrodes

    0
    SergeyF14
    SergeyF14

    5 years ago

    Hi and thanks for replying.
    Finally got time to play with it again and do some debugging.
    I was using ADS1115 board and at gain 16 it must have been too sensitive or something. Did a coversion of the reading to real mV on the screen and once set to gain 4 I finally get readings that are similar to the multimeter.
    Thanks again for the great post!