This is pretty much one of those required projects; everyone builds a datalogger in an Altoids can. But each is different and I enjoyed making mine.
- Uses ATmega328P (low power, 32K flash for lots of program space)
- Uses Maxim/Dallas DS1337 Real Time Clock (uses I2C)
- Logs data to microSD flash card, readable on PC (uses FAT32)
- Runs on two AAA alkaline batteries
- Low power draw (exact consumption varies based on SD card used)
- Supports RS-232 for entering commands
- Uses CR2032 lithium coin cell for RTC backup
- Uses Analog Devices TMP36 for temperature sensor (not shown, it gets wired to the green four-position terminal shown below)
- Uses SparkFun 3.3VDC boost converter to provide stable voltage even as batteries die
- ‘ve updated the photo (20 Oct 09) to show the datalogger after extensive updates. The red PCB in the center is a 3.3VDC boost converter from SparkFun that should give me lots of extra life from the two alkaline batteries; check out their NCP1400-3.3 board. The transistor just above the red PCB is the 2N3906, used to control power to the microSD card.
For more detail: Datalogger in an Altoids can