[quote author=Nick Gammon link=topic=138209.msg1038669#msg1038669 date=1355964075]
strykeroz:
... and the lowest value where the pin is guaranteed to be read as high is 0.6V. (this is from Page 313, section "28.2 DC Characteristics").
No. It is 0.6 * Vcc. So in the case of Vcc=5V that would be 3V.
[/quote]Thanks Nick - I re-read the datasheet and can see the hole I fell down. It really does say 0.6VCC and 0.3VCC so it looks to all the world like a voltage rather than a multiplier. Thanks for the correction.
Geoff