Still on the journey to complete an “upcoming project”, “ESP32 NTP Temperature Probe Cooking Thermometer With Steinhart-Hart Correction and Temperature Alarm” is an Instructable showing how I add an NTP temperature probe, piezo buzzer and software to my capacitive touch Instructable “ESP32 Capacitive Touch Input Using “Metallic Hole Plugs” for Buttons” to create a simple but accurate cooking thermometer with a programmable temperature alarm.

The three capacitive touch buttons allow the temperature alarm level to be set. Pressing the center button displays the “Set Alarm Temperature” display, enabling the left and right buttons to reduce or increase the alarm temperature respectively. Pressing and releasing the left button will reduce the alarm temperature one degree, while pressing and holding the left button will continuously reduce the alarm temperature until released. Similarly, pressing and releasing the right button will increase the alarm temperature one degree, while pressing and holding the right button will continuously increase the alarm temperature until released. When finished adjusting the alarm temperature, simply touch the center button again to return to the temperature display. At any time the temperature is equal to or higher than the alarm temperature, the piezo buzzer will sound.

And as mentioned, an NTP temperature probe is used in the design along with the Steinhart-Hart equations and coefficients necessary for accurate temperature readings. I’ve included an overly-verbose description of the Steinhart-Hart equation, the Steinhart-Hart coefficients, voltage dividers and algebra in Step 1 (as a bonus, it puts me to sleep every time I read it, so you may wish to skip Step 1 and head straight to Step 2: Assembling the Electronics, unless of course you need a nap).

If you decide to build this cooking thermometer, for customization and 3D printing I’ve included the following files:

Arduino file “AnalogInput.ino” containing the software for the design.
Autodesk Fusion 360 cad files for the case showing how the case was designed.
Cura 3.4.0 STL files “Case, Top.stl” and “Case, Bottom.stl” ready for 3D printing.
You will also need familiarity with the Arduino environment as well as soldering skills and equipment, and in addition may need access to accurate digital ohmmeters, thermometers and temperature sources for calibration.

And as usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes.

The electronics were designed using pencil, paper and a Radio Shack EC-2006a (Cat. No. 65-962a) solar powered calculator.

The software was designed using Arduino 1.8.5.

The case was designed using Autodesk Fusion 360, sliced using Cura 3.4.0, and printed in PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.

And one final note, I receive no compensation in any form, including but not limited to free samples, for any of the components used in this design”

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