The Simplest Thermometer

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The simplest digital thermometer possible.

Fig.1: The device still lacks some enclosure...

What's this all about?

Just for fun, I decided to build some simple thermometer that would run of batteries.

What is it exactly?

Just an AVR microcontroller (tiny13v) combined with DS18B20 onewire temperature sensor and a cheap LED display.

The device

It is very simple, even for my level. The schematic below shows it all - just a handfull of elements.

The device boots up, makes measurement via onewire bus. Then the result is displayed for about 10 seconds. After that time, the display is blanked out and device goes to power down mode. The only button is to reset the device - the routine is then repeated.

Device uses up below 45mA (consumed mostly by the display) while working and below 4uA when powered down. This allows 16000 measurement cycles (assuming 2000mAh batteries initial capacity). Idle time? Batteries will self-deplete long before theoretical last day of work comes.

There is not even a programming connector, I downloaded the code with my AVR_Programmer_Pogo_Adapter.

The gallery

Few pics to show sup:

Is it good?

Seems to work ok. Have to fix some enclosure for it.



pit, 2016-11-05