I have a 5V Arduino Mega 1280 board, and I need to use SPI bus to communicate with 64 chips(3.3V not 5V tolerant I/Os) I need to modify my board, I've changed 16MHz crystal with a 8 MHz one. I thought I can supply 3v3 to Vin pin, it worked but when I plugged USB cable(I need UART always), it runs…

Powering Entire Arduino Mega with 3V3

MarkT October 5, 2012, 12:56pm 7

The Seeed Studios guys have a Mega-alike board with 5.0/3.3 switchable Vcc: http://www.seeedstudio.com/depot/seeeduino-mega-p-717.html?cPath=132_133

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