There are some example projects using the ADC. In Creator Start Page use "Find Example Project" flll in PSoC5 family and look at the ADC projects. When having any further problems, consider posting your complete project, so that we all can have a look at all of your settings. To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file.
thanks for the response Bob.
I have gone through the examples. but could not succeed. i want to measure the voltage from 2V to 18 V. but it is not giving me the correct output.
Do not fry your PSoC!!! Input voltages are limited to VDDA which may not be higher than 5V. You will need a resistor ladder to reduce your input voltage to a maximum of your selected VRef of your ADC.