An I2C with Codec Problem

Are you using a security (non-copy) protocol?

No Just using normal I2C. In some registers I can write data and then when I read the slave(codec) I find the sent data which is good! but in other registers, the sent data is not the same as that of the reply done by the slave, ie the register is stored with a wrong value. But the value seems to be always the same as if it does not change, but in the datasheet nothing is mentiones :/

What Codec are you using?

Which registers are changing and which are not?

ADAV803

http://www.analog.com/static/imported-files/data_sheets/ADAV803.pdf

It would be helpful if you had access to a logic analyser or at worst a 2 channel CRO. Check your setup timing carefully. They indicate setup times over a uS in some cases. Have you successfully used I2C to talk to other devices or is this the first time on this platform?

Be sure about the proper h/w implementation of the I2C interface. However, this should not be the case, as you succesfully access some of the registers. Are you using the "Block Read & Write" method? Take a look on this issue in the I2C section of the datasheet. Probably, you don't actually access the proper registers (i.e. proper addresses), as you might think so.