Fri Feb 4 13:16:18 EST 2011
Interfacing 3V3 and 5V applications.
From : "There are many ICs available on the market that are
specifically designed to translate between logic levels. We've never
used any of them!"
The basic ideas are:
* 5V -> 3V: use a current limiting resistor. This requires the 3V3
input to be protected with clamping diode the 3V power supply!
* 3V -> 5V: no resistor necessary, inputs are compatible. I guess
it doesn't hurt to place one anyway in case master/slave roles are
SPI bus with the 5V device as master, as seen in the example in :
* MISO: master input slave output (3V)
* MOSI: master output slave input (5V)
* SCK: master clock (5V)