I'm hunting for guidelines on which families of chips I can use with 3.3v and/or 5v arduino cpus, like the AVR 328s on the Sparkfun Pro cpus. I would think the 5volt arduino cpu would work with all TTL and many CMOS chips. A helpful person on another topic summarized the 5volt compatible families as "The most common "modern" logic families compatible with arduino (ie 5V power supply) are 74hc, 74hct, 74ac, and 74act". That part's great. But which of those would (also) be happy with the 3.3volt arduinos?
Any particular types of CMOS chips I should look for?
When needed, what are people using as "level shifters"?
With your permission, I'll offer a summary of the answers here to Sparkfun and maybe even www.arduino.cc; I was surprised this information wasn't easily obtainable.
thanks in advance.
I never think too much about what families work, I just look at a particular chip I plan to use. That said
TTL/LSTTL etc -- nobody would uses any TTL family thses days I think.
Old CMOS -- works from 3v to 15v but once again few people would use it these days. I think some are plugged as level converters (4069?) though.
74HC/HCT etc etc. -- Probably all work at both voltages but as I said I only look at specific chips I plan to use.
Most of the modern CMOS (74HC..) will not like inputs > VCC, it's possible the old CMOS (4000 series) didn't have the protection diodes.
Some chips like the 74HC4050 (really just a 4050) can be used to down convert because the VCC diodes are designed to allow it.
When needed, what are people using as "level shifters"?
I like the TXB chips, TXB0101/04/06/08 from TI for bi-directional conversions. For large numbers of 5v -> 3v3 (say as inputs to a 3v3 board) chips like the 74LVC16245 seem petty good.
Rob