Abstract
In many areas of science, Arduino based data loggers have become common enabling instruments because of their low cost and ease of use. However, battery life is commonly the limiting factor - particularly in respect of writing data to embedded SD cards. In this paper, various methods by which to optimise an SD card based data logger using an Arduino UNO, Atmega328P at 5 V at 16 MHz and the Atmega328P at 3.3 V at 8 MHz is explored. With the bare Atmega328P chip in sleep mode, the lifetime of a 2400 mAH battery can theoretically exceed 10 years, although this is reduced to only 3 months following the introduction of an SD card. The exact power consumption of an Arduino/SD card during saving events is analysed for the first time and is found to take up to 200 ms with current spikes up to 80 mA for every initialisation and saving event dramatically increasing the average current consumption of fast data loggers. Through the use of a power control MOSFET with proper initialisation and timing of SD saving events, it is found that the Atmega328P can be set up to measure data once every two seconds whilst also ensuring a battery lifetime of one year. With the novel techniques presented here, a new method for maximising the lifetime of Atmega328P microcontroller circuits for environmental data logging applications has been achieved; allowing researchers to record data using a cheap and reproducible system.
Highlights
A S research progresses, the standard method for monitoring the characteristics of environments has become the use of sensors connected to battery powered microcontroller based data loggers [1]–[3]
When considering which microcontroller to use for such applications, researchers are spoilt for choice with many cheap and programmable controllers available
In terms of memory size, all of the microcontrollers listed are capable of supporting SPI interface with an secure digital (SD) card it can be seen that the LPC1768FBD and the ATSAMD21G18 provided the greatest flash and static random access memory (SRAM) sizes which could be needed for larger datalogging applications
Summary
A S research progresses, the standard method for monitoring the characteristics of environments has become the use of sensors connected to battery powered microcontroller based data loggers [1]–[3]. In order to maximise the lifetime of battery powered data logging projects, the power consumption of an SD card and the various methods by which to reduce the overall power consumption of the data logger circuit are compared. By analysing the transient waveforms of each topology, a significant increase in the average current consumption can be seen following the introduction of an SD card It is shown how the power consumption of the data logging project can be reduced significantly using a power control MOSFET and a threshold string-length method, reducing the original power consumption by over an order of magnitude, and greatly increasing the maximum achievable lifetime of the data logging circuit
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call