But in the manual it says that we never use constants for the I2C command.



What i have realised is that you refer to the

Code:
reg var byte
everytime you need to asign a constant value to it. Is that right? with that way we alter the restriction of using constants. (or am i wrong?)

in pbp constants are 16 bit, they are fine in i2c when a 16 bit value is appropriate and the endianness matches
if you use a var there is never any doubt, you get what you asked for but the endianness must match



im confused here. When do we use the write address and when do we use the read address!!!
there is no such thing as write address or read address in pbp there is only the address