Pictured above is a high accuracy (within 0.1°C) low power temperature data logger designed originally for scientific research in sea turtle egg incubation, but which could be put to use in a great many other applications.

This logger measures and logs the temperature once every 10 minutes exactly with sufficient memory space to hold 180 days of data (26,000 records). The logger is powered by a CR2032 coin cell battery which can keep it running unattended for the full 180 days.

When the measurement period is over, the logger can be extracted from its waterproof case and the logged data transmitted over a UART connection via a cable to a PC for subsequent analysis.

The goal of this project was to achieve all of the above at a cost per unit (of a batch of 50 units) of under €5, including the case.

The temperature sensor used is a 16-bit resolution digital MAX30205MTA+. This gives a temperature resolution of 0.00390625°C and 0.1°C accuracy in the range 0-50°C. The microcontroller chosen is the ATMEGA328PB – a slightly more feature rich version of the MCU found on many Arduino boards. The serial flash memory chip used is a 512kbit AT25DN512C from Adesto which has sufficient space to hold the 410-420kbit of data to be logged in six months.

For full details, plans, and discussion of this project, click here: Low Power Cost and Size Temperature Data Logger.