juztins-lab / roast-meter

Open source roast meter for arduino

Roast Meter

An awesome DIY projects that will help you get better consistent roasts by measuring roast color between batches

Report Bug • Request Feature

Table of Contents

• About The Project
• Assembly Instructions
• User Guide
• Calibration process
• Roadmap
• Contributing
• License
• Contact

About The Project

Starting into home roasting I've quickly realised the importance of a roast meter to evaluate the color of the coffee, this helps you better target different end temperature/time but retain the same level of color and see how it influences taste.

Here's why:

• Commercial grade roast meters are very expensive
• Chips and sensors are are readily available/cheap and easy to get going
• At the end of the guide you will have an ~100$ roast meter, that is consistent and can help you get the most out of your roast.

Check out our wiki for detailed instructions for assembly usage and calibration!

Assembly Instructions

https://github.com/juztins-lab/roast-meter/wiki/Roast-Meter-Assembly-Instructions

User Guide

https://github.com/juztins-lab/roast-meter/wiki/Roast-Meter-User's-Guide

Calibration process

https://github.com/juztins-lab/roast-meter/wiki/Roast-Meter-User's-Guide#calibration-methods

Roadmap

• Calibration against Agtron Gourmet Scale (DONE)
• Add battery, on/off button (DONE)
• Sensor calibration process - improved for consistency
• Mobile application to store coffee roast information as well as roast level and history (bluetooth)

See the open issues for a list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

Distributed under the GNU License. See LICENSE for more information.

Contact

Juztin - [email protected]

Project Link: https://github.com/juztins-lab/roast-meter

roast-meter's Issues

code installation software not working

hi guys, i am trying to install the software into my device but isn t working, I am following all the steps but nothing. Is there a video to follow instructions?

LCD-14532 replaced with LCD-22495

The LCD-14532 has been replaced with LCD-22495. I'm guessing this can be replaced without any action but you might want to update your link in the parts list.

Should we round the calculated Agtron result?

The way the Agtron conversion function f() is written, any decimal places are truncated. e.g. both 88.1 and 88.9 return 88 from this function. Is this intended?

I added the round() function before returning from f() so it will round the Agtron result to the closest integer. example:

return round((x - (intersectionPoint - x) * deviation) + ledBrightnessOffset);

Calibration against CM100 was done too fine, see sited article about deviation at sub 500um grind size on CM100+

I've also noticed this on my OMNI; if the ground is too fine, there can be a 20+ Agtron reading jump.

It is recommended to grind to SCA cupping size(roughly 750um-800um for the majority) for the CM100/+ and the OMNI.

I would suggest a recalibration process for this reader so it can trend properly.

relevant section: https://artisan-roasterscope.blogspot.com/2023/03/understanding-roast-color.html#:~:text=is%20kept%20constant.-,Particle%20Size,-The%20amount%20of

Bottom v.2.0.3mf contains no models in Cura

On attempting to open the .3mf, it will result in an error.

This isn't a major issue, as the other .stl file exists, but it is something to note.

Suggested updates to roast_meter.ino

1. Cleaned up unused code that was commented out and/or not functional.
   -- Rationale: make code easier to read and maintain.

2. Modified loop() to call getIR() one time per iteration so each rLevel is being tested AND displayed.
   -- Rationale: each call to getIR() removes a sensor result from a FIFO queue. Each iteration in loop() calls getIR(), tests it, then calls GetIR() again to display, so only every other sensor result is displayed.

3. Removed intToHex() function.
   -- Rationale: you can assign a value directly to ledBrightness. no need for this function.

4. Added ledBrightnessOffset calibration variable.
   -- Rationale: using ledBrightness alone, which changes LED amplitude, is too coarse for calibration. (e.g. changing it by +/- 1 causes as much as +6-7 points of Agtron reading change.) So, created an additional variable affecting the Agtron conversion formula. This approach first allows calibration for sensor hardware differences, and then calibrates the Agtron conversion formula to a desired target value to addresss any remaining inconsistencies. See comments in code.

5. Changed values passed to particleSensor.setup(). These are experimental but I'm not sure a high sample frequency is needed for measuring coffee vs the original intended use of the MAX30301 for HR/SPO2.
   -- Rationale: optimizing MAX30101 sensor settings for coffee measurements.

6. After calling particleSensor.setup(), added overrides to specifically turn off all LED's and slots on the MAX30101 except for the IR LED.
   -- Rationale: the code only calls getIR(), and in testing the red LED had no effect on the values returned by getIR() so turned it off. Also disabled slots for red and green LEDs. Purpose is to optimize the MAX30101 LED settings for coffee measurements.

See code changes here:
roast_meter_ino.zip

3D-STP files

Is it possible to share native 3D-files like stp ?
Thanks

3D Lid Print without Switch?

Sorry if I am asking this in the wrong place. Forgive me if I'm being thick here - but I can't seem to find the 3D print file for use without the battery.

Love the project. Thanks so much for all your work.

Does the OLED area expect a glass slide?

I'm not seeing this in the instructions, but does the LCD/OLED area expect a glass cover slide? Without one, it seems like the screen is quite far away from the actual top of the tray.

Progress bar in loading mode

Hello

I built the Roast Meter in the battery version. Everything seems to work as planned.
I can measure the tanning progress of the skin after a day in the mountains or at the beach.
It would be nice and helpful if there was a progress indicator for the charging mode.