TTT: Temperature based Tea Timer

Winter is coming…well…sort of. The season for hot tea is getting closer every day now. The color does not matter as long as a cup of tea makes the moment more hyggelig. Different teas need to steep for different amounts of time. Usually green teas taste better if they did not steep longer than 2 minutes. Black teas may steep longer, depending on the desired strength. Herbal and fruit teas may steep even longer, and why take the peppermint out of the cup at all?

Tea timers come in handy. So why not create one using an Arduino? But simply counting the time passed is trivial. It appears way more interesting to use the tea temperature to judge whether the tea is ready.


Arduino Pro Mini 5 V
Monochrome OLED display
TMP36 temperature sensor
Piezo Buzzer
Some cables


Arduino Pro Mini OLED Display TMP36 Piezo Buzzer
5 V 5 V 5 V
A0 middle leg
Pin 8 +


The Arduino sketch is pretty straight forward. In the loop the temperature is measured every second. The temperature is displayed along with the seconds passed since startup time on the OLED display. If the desired temperature is reached the display shows a message and the buzzer plays a melody. As a very simple safety measurement the time passed is taken into account as well…
The temperatures were measured with a cup of hot water and are to be considered experimental. The measured temperatures depend on various parameters and will vary in other environments.

The sketch can be uploaded to the Arduino using the Arduino IDE.

As suggested by deloarts the Arduino sketch can be found on github:

The Case

The temperature sensor should be close to the water. An idea which came up while working on this prototype is to create some kind of floating bubble with the display in the upper part and the temperature sensor in the lower half. TBD…

Prototype of the temperature tea timer
Prototype of the temperature tea timer