Interfacing a 3.3 volt device
There are different ways to connect a 3.3 volts device to a 5 volt Arduino:
and many more.
- voltage divider with resistors
- HEF 4050
(Actually, a 245 is much easier to layout than the cheaper 244.)
We go for no. 3, but experiments showed that even an old SN74LS245 does the job, if you happen to have some spare ones.
You have to connect CE(OE) to Gnd to enable the outputs and S/R(DIR) to Vcc to set the direction from A (inputs) to B (outputs).