What exactly is the problem? For reading the ADC data you use the AnalogIn objects, for the samplerates you use Ticker objects, the range you have to solve in hardware. I don't know which switch you mean. To communicate with TeraTerm you use a Serial object. Please define your problem more precisely and provide us with the code you think is right so we can point you in the right direction. The objects you require are described in the handbook. Regarding C/C++ coding there is information on the internet and in many, many books.

thanks for spearing your time to read my request. Am to use the internal ADC of Mbed NXP LPC1768 and display its output on a pc via tera term. the system has two cut off frequencies which is controlled by a switch i.e. for switching between the cut off frequencies of 10KHz and 100Hz. the voltage from the signal generator to the mbed is 4.5volts, which will go through high pass filter and, then switched to 1.20volts to go through a low pass filter. this will be implemented in hardware, then use the ADC of the Mbed and display the result via pc using tera term. the problem am having is the c code for adc conversion (Mbed) for the above frequencies. expecting your reply.. thanks