read codec(mic) help please....TMS320C6455 board

The Board Support Library from Spectrum Digital that comes with the DSK6455 includes source for all of the library functions, plus some excellent examples. The examples may  not do exactly what you want, but they are very good to use as a starting point to get a known-working example running, then you can modify that to get what you need. It is very helpful to start with the known case.

The default configuration used for most of the examples for the AIC23, as well as the labs we use in the TI Technical Training classes, generally use the Line In rather than the Mic In selection in the AIC23. This is easier for examples and labs since you do not have to be making sounds yourself into a microphone but can simply connect an MP3 player or your computer's headphone output to the Line In and have a continuous audio source for experimentation.

I have said all this because my first suspicion is that you do not have the AIC23 fully configured the way you want to use it. My recommendations may be starting at a point you have already passed, but it could be helpful to start there. You will be able to judge that for your situation.

Start with the "tone" example from the BSP files. On my system, these were installed at C:\CCStudio_v3.3\boards\dsk6455_v2\examples\tone . Tone is a good first project because it only requires a speaker so there are fewer places to have to debug at this point.

The "dsk_app" example is the next one to try. This will be close to what you need for your case, but it will be moving data from the Line In to the Line Out through the AIC23 and the DSP. Once you have this working, you are very close to having your project completed.

By examining the header file for the AIC23 (C:\CCStudio_v3.3\boards\dsk6455_v2\include\dsk6455_aic23.h), you will find constants that may indicate parameters to change to get the Mic In input selected instead of the Line In input. Since we do not have the exact example you want, it will be helpful to pull down the datasheet for the TLV320AIC23 so you can examine in detail the registers and the recommended methods to configure it. It may be worth a try to just change settings based on the example documentation and the header files, or you may want to study the datasheet to be certain what you are changing; and if hacking the example does not give you a solution quickly enough, the datasheet should have the information you need to get there.