nkokkos

nkokkos

I am doing my master thesis using Nerves

Hi everyone,

I decided to do my master thesis using nerves. Basically, the end product is a IoT device that connects to the local wifi and provides readings from an electrochemical C0 sensor through a web interface.

The CO sensor is an a professional sensor from Figaro, therefore I had to create an analog circuit on perfboard to capture the signal and then feed it into a breakout board I2C like asd1115 adc. I also use the breakout board bme680 since I need the temperature to do re-calibration of the sensor using a look up table. I also use the nerves key to do some sort of data push to an IoT platform. I plan to use the nerves cloud too. And finally I plan to use homex to push the data to a home assistant installation.

Most of the things used in the thesis/project have been covered here in the forum, plus in some nerves books that have been published. Through my research, no elixir nerves has been used before in thesis project in our department, so I suggested this proposal and my advisor gave me the ok.

In a nutshell, this is what this project does:

Uses a rasberry pi zero wireless, that connects to the perfboard where the CO sensor and the breakout boards are installed. Gets all the readings, provides all the readings through a poncho project using a web interface, pushes the data to an IoT platform and a local home assistant setup.

The most intriguing part was building the analog circuit interfacing the CO sensor since I had to go back to my undergraduate days and read all about operational amplifiers and low pass filters and all that.

I have started writing the code/firmware and the more I read and learn about nerves, the more amazed I become. Frank and all the people involved with nerves and the hex libraries have done a remarkable job and I thank you all. The documentation is so good.

This thesis is not rocket science but anyway I plan to release everything (source code and perfboard design) as a tutorial series, time willing.

Thank you for nerves!

Most Liked

lawik

lawik

Nerves Core Team

Delightful! Please keep us updated in this thread and share pictures :slight_smile:

nkokkos

nkokkos

Hi, I am uploading some pictures from the progress I have done so far.

The i2c breakout boards used are the bme680, the nerves key, and a cheap ads1115 adc,

The idea was to take an electrochemical sensor like the figaro tgs5042, which outputs a tiny current and superimpose it using an analog circuit based on an application note, and then pass the voltage produced to one of the adc inputs of the ads1115. I also use the bme680 to measure the temperature, since the temperature is used for a correction factor while calculating the CO ppm range.

I started with the idea to lay everything on a perfboard to reduce EMI but it turned out that was silly. So I kept the i2c boards on a breadboard and the analog part on a perfboard. Got really frustrated with the dupont cables and their connections.

I am currently running on the very first rpi0, one core cpu, sampling the inputs of the ads1115, doing median filtering to remove emi noise and pushing data to liveview using the classic poncho scheme. Code is almost complete and I was impressed that it worked. I am currently doing experiments now with measurements and I will provide a link to github in short time.

On the breadboard, you can see that I had to use coupling capacitors before the inputs. Coupling capacitors are used also on the perfboard to stabilize the voltage source

nkokkos

nkokkos

We did some real tests today at the university’s chemistry lab. The screen shots show the phoenix liveview page running on rasberry pi zero wireless sampling every 15 seconds. You can see the CO ppm shoot up at some point and back down again. These are all simple liveview pages, nothing fancy, but it was really exciting to see the immediate response from the sensor.

By the way, I found on youtube this https://www.youtube.com/watch?v=f0VPFwnBOO0 where the guy dissects a classic CO domestic which uses the tgs5042.

Where Next?

Popular in Discussions Top

AstonJ
Please see the new poll here: Which code editor or IDE do you use? (Poll) (2022 Edition) It’s been a while since we first asked this, I...
208 31695 143
New
ben-pr-p
In general I’ve been sticking to this community style guide GitHub - christopheradams/elixir_style_guide: A community driven style guide ...
New
Crowdhailer
I’ve been hearing much about the new formatter and it’s something I have been keen to try. I find examples buy far the most illuminating...
248 19740 150
New
pillaiindu
In django there is a cache framework backed by memcached. Rails also puts a lot of emphasis on caching, and even the idea of russian-doll...
New
lorenzo
Hey everone! I created a prototype for my app using Nodejs for the api. But the framework I chose wasnt great (in general theresnt any g...
New
PragTob
Hello everyone, I know we had quite some threads (read through lots of them) about background job processing but it remains a hotly deba...
New
slashdotdash
Phoenix Live View is now publicly available on GitHub. Here’s Chris McCord’s tweet announcing making it public.
New

Other popular topics Top

Brian
What is the proper way to load a module from a file in to IEX? In the python world, doing something like this pretty standard: from ....
New
dokuzbir
I want to highlight html closing tags when i click a html tag. That works in .html files but doesnt work for html.eex templates. How can...
New
Darmani72
If I have a post route which an argument: post /my_post_route/:my_param1, MyController.my_post_handler How would get the post params ...
New
bsollish-terakeet
Credo is smart enough to check for (something like) this: assert length(the_list) == 0 with this response: Checking if an enum is empt...
New
shijith.k
I am trying to start a new phoenix project with elixir 1.9, but mix phx.new does not work. It says that ** (Mix) The task "phx.new" could...
New
sergio
Kind of like when jquery came out, it was super necessary. Existing drag and drop libraries have a bunch of baggage to support old browse...
New

We're in Beta

About us Mission Statement