AVR-Chat

Jim White wrote:
> We are working up a Mega128 based board that will have both 5V and 3V 
> parts. The 128 will run at 5V.  Anyone have suggestions for converting the 
> 5V logic levels to/from the 128 to the 3V levels needed for some of the 
> other components.  Space is at a premium.
> 
> Jim

For 5V_cpu->3.3V_ttl use a series resistor (less resistance for more speed).
for 3.3V_ttl->5V_cpu use pullup resistors to 3.3 or 5V.

For more speed and less power consumption, use a 5/3.3V interface chip.