This project shows you how to store data into microSD card in files with FAT32 format using microcontroller AVR ATmega32. The MCU receives sensor’s data through internal ADC. You can connect up to 8 different sensors to the system.
In this project, Dharmani uses one channel to read temperature value from LM35 sensor and remain channels are used for simply reading voltages and storing them. The data is stored in CSV (comma separated values) format, which can be read using a PC/Laptop with Microsoft Excel or other compatible software.
For more detail: AVR Data Logger with MicroSD using ATmega32 microcontroller