can anyone tell the how to write the code for 3 channel ADC and microcontroller interfacing.plz it's very urgent,
"You pick up all relevant datasheets. You read every single line in the datasheets about the ADC..."
In addition to the datasheets, be sure to check the manufacturer's website for application notes, design hints, examples, etc, etc...
Also check the examples included with your Keil tools - they're also available in the 'Support' section of this website...