Stand alone data loggers are compact, reusable and portable. Here we have used 2GB SanDisk Micro SD card to act as an external memory device to store environmental data. Micro SD card supports SPI and so it is interfaced with MicroController Atmega 32. The data is transferred between the memory card and the host controller as data blocks in unit of 512 bytes. data is stored using FAT32 library by elm-chan. Various sensors like temperature sensor (LM35) Pressure Sensor (MPX4115), height sensor (GP2D12) etc are interfaced to MCU using ADC port. To give data according to real time we have used Real Time Clock (RTC) DS1307 . It is interfaced with MCU using I2C protocol. Data received by sensors are directed to MCU where it is processed and directed to micro SD Card with real date and time. Data is stored in CSV format so that we can read the date in Microsoft Excel.