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Roast Meter Assembly Instructions

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nsolling edited this page Oct 20, 2023 · 45 revisions

Getting Started

  • Get your hardware
  • Print your 3D case and apply glass sensor window
  • Assemble the electronics and install the software
  • Put everything into the case

Prerequisites

Hardware

Software

Misc

Tools

  • Stanley/X-Acto knife with new blade to score glass for cutting
  • Ruler and pen
  • Pliers, screwdrivers and other hand tools
  • Soldering iron, solder, and soldering tools (if building battery powered version)

Installation and Assembly

Assembling the Roast Meter is relatively simple and anyone with a bit of basic tinkering skills should be able to make the Roast Meter. The hardest part is probably cutting the glass, but since you have most likely bought an ample amount then you can afford to break some.

3D Print the Case

First choose the right 3D print model by reading the instructions in the /3D Print folder. The base is the same for both the battery and non-battery model. For the top make sure you choose the model which is correct for your requirements.

NOTE: There is no difference in the measurement performance of the battery vs. non-battery version. The only difference is that with the non-battery version you need to power the meter from an external power source, whereas the battery powered version is powered by the built- in LiPo battery cell. If you are not confident at soldering maybe stick to the non-battery version as it is then pretty plug and play.

NOTE: If you're having the case printed, consider getting 2 of them in case you make a mistake.

Cut and test fit glass in the case lid

CAUTION: Wear gloves and eye protection for this step to reduce risk of injury.

NOTE: Some have tried using slide cover slips to avoid this step. But the cover slips are too thin and will break in use.

  • Take a lab slide and measure 25 mm length and mark with a permanent marker on the glass.
  • Place the glass on a hard surface and place a ruler (Best is metal) on the glass and score a line in the glass with the Stanley/X-Acto knife.
  • Move the slide to the edge of a hard surface right at the score line. Place the metal ruler on top of the slide at the score line. While wearing safety gloves, gently lift the slide to break the glass. You should end up with a piece that is approximately 25 x 25 mm
  • Verify the glass fits in the 3D printed top. You may need to lightly sand the case or nip the edges of the glass with the Stanley/X-Acto knife to achieve fit.

Glue the glass into the case lid

  • Place 4 tiny drops of super glue, or other suitable adhesive, on the 3D printed top, where the glass needs to go.
  • With glue less is more; we are really talking about a tiny drop. Keep the glue ~5mm from the sample port hole in the lid to avoid having it intrude on the glass.
  • Place the glass carefully so that it is tight on the top corner of the chamfer made for the glass, press firmly and wait for glue to cure.
  • Clean the glass to remove any glue residue using isopropyl alcohol.

Assemble electronics

It's a good idea to connect the electronic components together and test them before installing in the 3D case. The order of the sensor and display components do not matter as they use an I2C bus. Once the components are connected using the QWIIC cables, then connect a USB-C cable to your computer. You should see a power light on the Artemis Thing Plus board.

Installing computer software and uploading code to the Artemis Thing Plus

The Artemis Thing Plus supports the Arduino standard. Refer to the Arduino and Sparkfun websites for detailed instructions or updates.

  • Install the Arduino IDE software you downloaded onto your computer using this guide
  • Copy the roast_meter.ino source code file to your computer and open it in the Arduino IDE.
  • Install the Board Manager in the IDE using this guide
  • Install the Micro OLED and MAX30101 libraries (ZIP file) you downloaded using this guide
  • Connect to the electronics from within the IDE as follows:
    • From the IDE, select Tools/Board/Sparkfun Apollo 3 boards and choose the "Artemis Thing Plus"
    • Select the COM port on your computer where USB-C cable from the electronics is connected too. From the IDE, select Tools/Port and pick the COM port the USB-C cable going to the electronics is inserted into.
  • From the IDE, select Sketch/Verify to compile the software. If all went well, select Sketch/Upload to send the compiled code to the Artemis Thing Plus.

Test the software

If everything is uploaded correctly, you should see a message on the display to install a sample. Wave your finger or a small piece of paper over the sensor and you should see a number on the display. Now you're ready to install in the case.

Install electronics in 3D printed lid

  • Connect the MAX 30101 sensor and Micro OLED display using the 50mm QWIIC cable.
  • Use M3 x 4mm screws to install the components as shown. Tighten the screws gently.

Install electronics in 3D printed base and attach lid

  • Connect the Micro OLED display to the Artemis Thing Plus using the 100mm QWIIC cable.
  • Use M3 x 4mm screws to install Artemis Thing Plus as shown. Tighten the screws gently.
  • Attach the lid to the base using the M3 x 16mm screws. Tighten the screws gently.
  • If you are not including the battery option, your Roast Meter is now ready for use! Simply connect it to a USB-C cable which is attached to a power source (computer, external battery or wall wart).

NOTE: The cardboard shield's purpose in this photo is to limit light reflection. It is optional and not required.

Internal Battery Option

For convenience, an optional rechargeable battery and power switch can be installed in the Roast Meter. When a USB-C cable attached to a power source is connected, it will both power the Roast Meter and charge the battery. This option requires soldering equipment and skills not discussed here.

  • Check that the polarity of the LiPo battery you purchased matches the JST connector on the Artemis Thing Plus. If it doesn't you need to swap the leads on the battery connector.
    • CAUTION: FAILURE TO DO THIS WILL DAMAGE THE ELECTRONICS.
    • Gently lift the plastic on the battery's JST connector with the Stanley/X-Acto knife just enough to allow you to pull a power lead free. Do this one at a time and be careful because the plastic is easy to break. Swap and insert the leads back into the battery's JST connector until it clicks.
  • Installing the power switch:
    • Cut two strands of wire to 100mm, then strip the ends and tin with solder.
    • Solder one end of each strand into the EN and GND through holes on the Artemis Thing Plus.
    • Solder the other end of each strand to one throw of the switch.
    • Use a multimeter to verify a good circuit, then connect the battery to the Artemis Thing Plus. Verify the switch will power the Roast Meter.
    • Mount the battery into the case using double sided tape or Velcro.
    • Install the switch to the lid using the M2 x 2mm screws, and attach the lid to the base using the M3 x 16mm screws. Tighten the screws gently.

Rev. 1.0 5

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