A Mini Pearl Logger is also available in two kits which require soldering: a basic kit and a Pro kit with TPL5110 timer and minimal accessories.

This kit can be assembled in 15 minutes into a data logger which can record data every few minutes for many months on power from a few small batteries. The logger is based on an Arduino Pro Mini microcontroller and a separate timer which turns the Arduino on and off so it logs data at a selected interval. Connections among the Pro Mini and four other electronic modules are made with DuPont wires and require no soldering.

One of the components of this logger is a low power timer which turns the other components on only for the few seconds needed to collect data and save it to the microSD card. The timer can be set with a small screwdriver to an interval between less than a second and two hours. The timer itself uses power continuously, but it would take a couple of years to run down three AA alkaline batteries. At the selected interval, the timer turns on the other components so sensor data can be written to microSD card. This takes only a few seconds so little additional power is used. When the logging event is finished, the Arduino sketch sends a signal to the timer to cut the power until the next event.

With a 10 or 15 minute interval between logging events, the estimated longevity of three AA or AAA alkaline batteries is several months to a year. Because the timer controls the Arduino, the sketch running on the Arduino can be very simple and easy to understand and modify. The included Arduino has a sketch installed which will write temperature and barometric pressure data to the microSD card at an interval determined by the timer. You can set any interval with a small screwdriver. To modify the sketch, the free Arduino IDE program or WEB Editor is required. 

This is similar to the Mini Pearl Logger Kit but the Mini Pearl Snap also includes the TPL5110 timer, a UART adapter cable, and a sensor.

The included 3.3 volt Arduino Pro Mini supports sensors which can operate on 3.3 volts. Many of the sensors available here can be used. The TPL5110 timer must be powered with batteries which supply between about 3.5 volts and 5 volts. Do not connect more than 5.5 volts to the timer. 

An assembly and user guide is available at the Guides page. There are some research notes about the Mini Pearl Logger at Public Lab.

Parts List:

• Arduino Pro Mini compatible microcontroller (3.3v)
• Adafruit TPL5110 Low Power Timer
• MicroSD card board (3.3v)
• 1 GB microSD card
• Real time clock (DS3231) board (3.3v or 5v)
• CR2032 coin cell battery for RTC
• BMP280 sensor for barometric pressure and temperature
• Case for three AA or AAA batteries (has switch and leads)
• Custom 3D printed mounting plate
• UART adapter to connect logger to a computer
• USB cable
• 23 DuPont wires

You must supply:

• three AA or AAA batteries (alkaline or rechargeable)
• small screwdriver (to adjust trimpot on timer to set logging interval)
• additional sensor (optional)
• microSD card reader
• weatherproof enclosure for field use
• Arduino IDE for modifying the sketch (program)
• modified sketch for additional sensor