AVR-Chat

Anybody know what the best way is to interface a 5V output on my
Mega64 to a 3V input on a Nordic RF IC ? The Nordic datasheet
specifies a max input voltage of VDD + 0.3V (3.3V)

BTDT.



> Best way I could come up with was a voltage divider on each line, but
> theres six lines, so thats 12 extra resistors !


Resistors are cheap..

You can also use a Szaiklai pair, to convert the 3V outputs to 5V rails



> I need to run the Mega at 5V because of interfacing to other 5V
> components, so running it @ 3V is not an option unfortunately.


Realize that a high output on a 3V processor is a high input on a 5V CMOS or
TTL input.
Lows on both families are compatible.



> I assume that outputs from the Nordic IC to input pins on the Mega
> will be no problem for straight connection due to the high input
> impedance of the Mega and I would not need to use the pullsups on the
> Mega because the RF IC drives the line both low and high. It looks
> like anything above 1V on the Mega is seen as a 1.


It's not as hard as you think.


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