Below i show a newer pcf8574 serial lcd module and circuit, note "do not solder this module to an lcd" ... the wiring on the module is different then others i have seen, use a solderless breadboard and play with the modules wiring and code. also... set A0, A1, A2 address solder points accordingly to your software. (note: an open address solder point is considered a "high" ("closed is low or ground"), there is a 10K resistor on pins 1,2,3 (A0,A1,A2) of the pcf8574, not shown in the drawing, i noticed this later. Note: the circuit does not show back light circuitry...
Good Luck!
Pictures Here...
https://drive.google.com/folderview?id=0B2PvPbdPhghXNFh1ZXVlUzlkU1k&usp=sharing
Good Luck!
Pictures Here...
https://drive.google.com/folderview?id=0B2PvPbdPhghXNFh1ZXVlUzlkU1k&usp=sharing