ADC programming

Enable_ADC();
ADC_Start_Conversion();
while(!DataReady);
data = ADC_GetData();

or....read the data sheet for you micro and learn!

Note that they haven't been called "Cygnal" for years now - maybe that's why you're having trouble finding the info?

Try looking under "Silicon Laboratories" or "Si Labs" instead...

It's also not a '251 - it's a '51 derivative.

Firat time i am using 8051 silicon microcontroller. I have assigned one project in that ADC, DAC, Keyboard, LCD everything involved. can you suggest some material that covers all the above thing

For generating sine wave, look up tables they r using. how they selected values in the array.