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GPS to SD-Card Data Logger
This project combines a GPS receiver module, a Microchip PIC microcontroller and a Secure Digital memory card to make a GPS data logger.
The data from the GPS is logged every second with the raw NMEA sentences being written to the SD card.
The total active power consumption is about 40mA to 45mA when active which in theory should give 48 hours on rechargeable batteries with 2000mAh capacity.
The data is written to the SD card in blocks of 512 bytes (the native SD card block size). One block is written each second and padded to 512 bytes with zero bytes. Starting and stopping is recorded by a blank block in the SD card. There is no file system on the SD card so it needs to be read byte by byte (easy in Linux using a USB adapter and reading the raw device). 512MB SD card allows to store of 1 million data points. Any capacity card up to 2GB could be used without a change to the software.