I roasted four batches of coffee in my Bullet today and then loaded the BlueTooth version of code on my Roast Meter and included the ArduinoBLE.h code in Arduion to try it out. I directed my phone to https://roast-meter-app.hh.coffee/ and connected to the roast-meter to try the display and settings. It works pretty good and allows you to change and store the LED brightness, Intersection Point, and Deviation settings in EEPROM. I don't really know what the Intersection Point and Deviation settings do yet.

I pulled some samples at first crack but got some high readings ~118 where I'd expect something around 95 for the Gourmet Agtron scale and based on the Sweet Marias roast color cards I picked up but I didn't have the time to get into looking at how I could adjust things to expected readings beyond just the basic calibration of baking soda with the LED Brightness.

Brewzologist wrote:As promised, a couple photos of the completed build with battery and switch. You can just use USB-C to power the RM if you won't want to mess with soldering.

This quote is from post #24. If a person didn't want to solder to the Artemis board, couldn't they put the switch in line with one wire of the battery lead? When the switch is turned on or off, the meter is on/off as normal... To charge the battery, the switch would need to be in the on position and the USB-C connected. Any thoughts or input?

Seems like it would work, but if you plugged in the USB with the switch off the roast-meter would be powered on and the battery wouldn't be charging, but as long as you don't have the USB plugged in, you could use the switch to interrupt the power from the battery and turn the board on and off.

yakster wrote:Seems like it would work

Thanks. I'll try it in a couple of days when my battery arrives and report back. I prefer not to solder to the main board.

Transparent Roaster wrote: This quote is from post #24. If a person didn't want to solder to the Artemis board, couldn't they put the switch in line with one wire of the battery lead? When the switch is turned on or off, the meter is on/off as normal... To charge the battery, the switch would need to be in the on position and the USB-C connected. Any thoughts or input?

Shorting the EN and GND pins on the Artemis Thing Plus causes the board to turn off while still allowing it to charge the battery when connected to a USB-C power source.

If you just splice a switch into the battery lead it may work but you'll have to turn on the switch to charge the battery. If you go that route I'd splice both battery wires and use a DPDT switch too to avoid any issues with the charging circuit on the Artemis. And those battery wires are tiny too.

All that said, I think you'll have to solder anyway, so not sure that approach saves you anything.

Brewzologist wrote:If you just splice a switch into the battery lead it may work but you'll have to turn on the switch to charge the battery. If you go that route I'd splice both battery wires and use a DPDT switch too to avoid any issues with the charging circuit on the Artemis.

Thanks for the added information. That's what I was wondering, whether or not a switch might affect the charging circuit (or ability to charge) when inline. I was planning on using either a toggle switch SPST for a single lead (https://www.amazon.ca/dp/B07S1MV462?psc ... ct_details), or a latching LED push button switch with leads for both positive and negative. My battery has a larger size and mah rating than the original specs (https://www.amazon.ca/dp/B082152887?psc ... ct_details) and shouldn't need charging often for my limited home roasting usage.

Brewzologist wrote:If you just splice a switch into the battery lead it may work but you'll have to turn on the switch to charge the battery. If you go that route I'd splice both battery wires and use a DPDT switch too to avoid any issues with the charging circuit on the Artemis. And those battery wires are tiny too.

Why would that be better than a single switch on one lead?

Brewzologist wrote:All that said, I think you'll have to solder anyway, so not sure that approach saves you anything.

It saves him from soldering to the board. I'm not sure why that's an issue. Maybe he's borrowing it and needs to return it? Who knows.

An update... the color meter works great. All the components have been installed in a new custom-designed case that provides a better user experience IMHO. It has a rocker switch inline on the positive battery lead that allows for cable-free operation. When it's plugged in using the USB-C cable the operation is normal. When you flip the switch "on", the board's charger circuit activates to replenish the battery while connected to the USB-C. Unplug the cable and enjoy wireless operation anywhere. I'm quite happy with the results.
I'd like to thank all involved who offered the open-source programming on GitHub.

Transparent Roaster wrote:...a new custom-designed case that provides a better user experience IMHO.

What's different about it?

As far as I can see, the color meters that are on the market typically take a top-down scan versus a bottom upwards scan. Devices are placed over a sample, and not vice versa.

I designed a new case with that in mind. With this approach, no coffee or residues will ever cloud the sensor window. Another detail is that it seemed the original roast vision calibration could vary depending on how much pressure was applied to the calibration material placed over the scan glass. That is less of an issue with this design, and the readings are stable on its calibration pad.

This design can be placed on a single sample and multiple readings taken for an easy average of the color... on the original, you'd have to dump the sample multiple times and measure again. Overall, the user experience is faster and cleaner. I use the meter on my espresso grind just before pulling the shot. I'm now taking a reading beforehand to better understand my roasts.