ADC of ARM7 ( LPC2148 )


What is ADC ?

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device that converts a continuous physical quantity (usually voltage) to a digital number that represents the quantity’s amplitude.


How ADC work 

Most real world data is in analog form. Whether it be temperature, pressure, voltage, etc, their variation is always analog in we have to convert this analog data into digital format so that computer or microcontroller can understand it and process on it. Sensor gives analog data in form of variation in current and voltage, ADC read this variation and process a digital data according to analog input and send to microcontroller to process it further.

Terms used in ADC

Resolution – The resolution of the converter indicates the number of discrete values it can produce over the range of analog values. A computer is a digital machine that stores a number in binary. If you are storing a digital 2-bit number you can store 4 different values: 00, 01, 10, or 11. Now, you can say ADC have 2-bit resolution and you have a device which converts an analog voltage between 0 and 10 volts into a 2-bit digital value for storage in a computer. This device will give digital values as follows :



2-Bit Digital Representation

0 to 2.5


2.5 to 5


5 to 7.5


7.5 to 10



Higher the resolution smaller the step size
Smaller the step size better accuracy

  • Step size – small amount of change in analog input that can understand
    for example 8-bit ADC, step size=Vref/2^8 = Vref/256
    Vref – used to detect step size
  • Conversion –
    Dout=Vinput/(step size)
    Dout – decimal output digital data
    Vinput – analog input voltage
    For example – for 8 bit ADC, Vref = 2.56 V, calculate digital output for 1.7 V input.
    step size=(2.56 V)/256=10 mV
    Dout=(1.7 V)/(10 mV)=170=10101010


Feature of ADC in ATmega32

  • 10bit ADC inbuilt
  • 8 analog input channel (ADC0 to ADC7 = PORTA)
  • 7 differential channel input
  • 2 different input channel with gain of 10X and 200X
  • 3 option of Vref
    1). internal 2.56 V

    2). AVcc (pin 30)
    3). AREFF (pin 32)




used to read analog input data from sensor in our application.

Click Here : Program point of view understanding of ADC





1. Program Of ADC Of  ARM7 (LPC2148) 

In this program TEMPERATURE data is appeared on the LCD connected to the controller using ADC


PROTEUS File for SIMULATION(Password Of RAR file is

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