how to use in-built adc of avr


Posted on Feb 7, 2014

Microcontroller understands only digital language. However, the inputs available from the environment to the microcontroller are mostly analog in nature, i. e. , they vary continuously with time. In order to understand the inputs by the digital processor, a device called Analog to Digital Converter (ADC) is used. As the name suggests this peripheral gathers the analog information supplied from


how to use in-built adc of avr
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the environment and converts it to the controller understandable digital format, microcontroller then processes the information and provides the desired result at the output end. ADC channels in Atmega16 are multiplexed with PORTA and use the common pins (pin33 to pin40) with PORTA. ADC system of Atmega16 microcontroller consists of following pins: ii. AREF: Pin32 of Atmega16 microcontroller, the voltage on AREF pin acts as the reference voltage for ADC conversion, reference voltage is always less than or equal to the supply voltage, i. e. , Vcc. iii. AVCC: Pin30, this pin is the supply voltage pin for using PORTA and the ADC; AVCC pin must be connected to Vcc (microcontroller supply voltage) to use PORTA and ADC. Connect the circuit as shown in the circuit diagram. A ceramic capacitor 104 is connected in between AVcc (pin 30) and Aref (pin 32). AVcc (pin 30) is connected to external supply +5V.




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