I'd like to make a GPS logger. I've got a GPS from Microsoft Streets and Trips. I read that it communicates at 4800 baud over RS232 at 3.3 or 5v. I've got an MSP430G2231 from the launchpad kit and I'm a bit fuzzy on how to talk RS232 to this thing. I also want to write to an SD card, preferably to a file so I can pull the data off with a computer. The raw NMEA strings are fine, I can parse those on the computer. The more detail the better. Thanks.
The MSP430G2231 doesn't have a hardware UART. The best option is to use a timer to clock your bits in and out.
Here's a good example of how to do this: http://www.msp430launchpad.com/2010/08/half-duplex-software-uart-on-launchpad.html
Wire your GPS to TX, RX and GND on your Launchpad board.
Writing to an SD card is more tricky. SD cards talk a protocol on top of SPI. I've written a Bus-Pirate-like SPI explorer for the MSP430 which should get you some of the way there:
On top of the SPI code you'll also need an SD card driver and a filesystem driver (likely FAT if you want Windows compatability). You could simplify things by writing raw data to the SD card - though this will make it harder to read at the Windows end. Linux could read it with
I'd choose a different chip, with a UART. A software UART can be implemented on that chip, of course.