March 7, 2010
about 5 years ago
The issue is with the communication between the Arduino (5v logic) and the sd card (3v3 logic). There are a couple of options for level shifting - you can use simple resistor-based voltage dividers for the connections that need to be shifted, or better yet a level shifter IC. I’ve read that the resistor-based approach can cause timing issues for newer SD cards, but I’ve used that method with no problems so far. Maybe I’m just lucky.
You can find a schematic for a resistor-based level shifting SD card interface here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1206874649/0
There’s also excellent info on Arduino->SD card communication in the SdFat lib documentation: http://code.google.com/p/sdfatlib/
If this shield had an integrated level shifter, I’d buy a few of ‘em.
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