For signals from the flash IC to the Arduino just connect directly (or add a series 1k resistor to protect the flash chip
should you accidentally configure that Arduino pin as an output).
I remember reading about interfacing like this because of the low TTL high threshold. I should have thought, many thanks!
However, re the series resistor? Whilst this'll limit current, obviously, how does this protect the 3.3v device from a 5v over voltage? 5v is still going to flow through the 1K?
oric_dan(333):
If you take slightly larger values for the v.div, namely 2.4K and 4.7K, and a largish 40pF
estimate for gate capacitance, then the time-constant is R*C= 1.6K * 40pF = 64 nsec.
That's still pretty fast. It would probably work, except at very fast SPI clock frequencies.
When you say "very fast", faster than the frequency used in the standard Arduino SPI library?
Also, where does the 1.6k come from in the calculation? 4k7 - 2k4 = 2k3... Not from there.