The 220Ohm resitor is not necessary for the PCF because its maximum current is somewhere in the range of µA and it cannot be damaged. For a connection directly on the IO-Pins of the Atemga they are necessary.
The 220Ohm resitor is not necessary for the PCF because its maximum current is somewhere in the range of µA and it cannot be damaged. For a connection directly on the IO-Pins of the Atemga they are necessary.