Hi,
I couldn't find a suitable Arduino library for HD44780 LCD displays with generic Chinese PCF8574 I2C extenders, so I modified 'LiquidCrystal_I2C' ~Mario H.
Here's the result:
https://github.com/vanluynm/LiquidCrystal_I2C
or
http://members.iinet.net.au/~vanluynm/Down/LiquidCrystal_I2C.zip
Enjoy!
I'm not sure where to start.
How hard did you look when you searched for a suitable library? Did you find any real problems with the one written by 'FM' https://bitbucket.org/fmalpartida/new-liquidcrystal/wiki/Home ?
What do you mean by a 'generic' Chinese extender? There's no standard for the connections between the 8574 and the 16 LCD module pins. Does your library provide any means to deal with this?
Can you give us any background on how your library is better that the one you modified?
Don