I/O current constraints for new Arduino ARM boards?

Other Hardware 3rd Party Boards
1

I have just received a couple of Zeros and am looking to hook up a few devices (not shields) to them.

With a current limit of only 7ma on the pins I need to know whether there are any changes necessary before to connecting to other 3.3 volt devices? (specifically Wiznet W5100 ethernet module, RF22B wireless modules, Zigbees and RS232 transceivers)

For SPI, IC2 and 3.3v RS232 chips, is there a general standard where they will not source or sink more than, say, 5 ma at 3.3 volt on their I/O pins? Do I need to put a 510 ohm in series with each connected I/O pin or will this stuff up the signals?

2

lemming:
Do I need to put a 510 ohm in series with each connected I/O pin or will this stuff up the signals?

No, yes.