This versatile data logger is built around the AVR Butterfly. It is a cost effective solution that monitors light, temperature, battery voltage and external sensors. The external sensors can be digital signals, analogue voltages or a frequency. There is provision for up to four external analogue sensors in addition to those shipped on the butterfly for temp, light and battery voltage. Although the digital sensor interface is currently designed to use Phillips I2C it could easily be expanded to include a Dallas 1-wire bus as well. Simple wake-up circuitry was implemented to wake the device from sleep when a serial connection was made by emulating a click on the joystick on a rising edge from the DTR signal.
A major feature of Butterfly data logger is customization. The goal was to develop a code base for the development of low cost data logging devices that could be quickly developed to suit specific needs. In developing this project I explored two options. The first is a low data rate, long life, weather station. The second is a short-term, high data rate, acceleration logging device. The code is easily customized as channels and sensors can quickly be removed by editing pre-processor definitions in main.h and other header files. Butterfly Data Logger project is designed by Nick Lott.