PICs and other µCs have UARTs - that's not the same as line drivers or transceivers. Fig. 9 in the WizFi210 manual makes it clear that it has 0-3V levels. The US dealer for WizNet checked the output of the Wiz105SR - it's 0-3V so it will need level conversion which can be as simple as a Schottky diode and pullup resistor (which will also work with a 3.3V supply). See this drawing which shows another (part of a) shield I'm working on that has six such level converters ... Name: max4321e.png Views: 5768 Size: 19.8 KB