AVR Microcontroller Questions and Answers for Freshers on “ADC, DAC Interfacing”.
1. Which of the following is correct about the word resolution in ADC DAC converters in AVR’s?
a) it is the smallest change that can be described by an ADC
b) it is equal to Vref/2n (where n represents the number of bits)
c) it is 0.076mV or 76uV for n=16 and Vref=5V
d) all of the mentioned
Answer: d
Clarification: Resolution is defined as the smallest change in the step size that is described by an ADC, it is equal to Vref/2n.
2. In an ADC, we can calculate the output voltage from the formula
a) Step size / Vin
b) Step size * Vin
c) Vin / step size
d) Vref / step size
Answer: c
Clarification: The output voltage can be calculated by using the formula Vin / step size.
3. ADC0848 is a ____________ bit converter?
a) 16
b) 4
c) 8
d) 48
Answer: c
Clarification: ADC0848 is a 8 bit converter.
4. Which of the following factors can affect the step size calculation?
a) number of bits
b) input current
c) output current
d) all of the mentioned
Answer: a
Clarification: There are mainly two factors that can affect the step size calculation of an ADC converter, they are the number of bits and the Vref voltage.
5. MAX1112 is a _________ type of ADC converter?
a) parallel
b) 12 bit
c) serial
d) all of the mentioned
Answer: c
Clarification: MAX1112 is a serial ADC converter, as it has only one pin for the data output.
6. Why do we connect a capacitor between the Vref and the Gnd pin?
a) to remove the leakage
b) to ensure more current at that place
c) to make more Vref
d) to make Vref stable and also to increase the precision of the ADC
Answer: d
Clarification: A capacitor is connected between the Vref and the Gnd pin in order to stabilize the Vref value and also to increase the precision of the ADc converter.
7. Which of the following are the registers that are used for controlling the ADC conversion in the AVR?
a) ADCSRA
b) ADMUX
c) SPIOR
d) All of the mentioned
Answer: d
Clarification: For programming the ADC conversion in an AVR, we require the following registers. They are ADCSRA, ADMUX, SPIOR. There are two more registers used for handling the output data, they are ADCH and ADCL registers.
8. What is the internal Vref of an Atmega32 series?
a) 5V
b) 3.3V
c) 2.56V
d) all of the mentioned
Answer: c
Clarification: 2.56V is the internal Vref selected for an Atmega32 series based microcontrollers.
9. The output of a DAC0808 is in the form of ____________
a) electrical pulse
b) current
c) voltage
d) all of the mentioned
Answer: b
Clarification: The output of a DAC0808 is in the form of a current.
10. In a DAC the input is ______ and the output is ______
a) analog, digital
b) current, voltage
c) digital, analog
d) analog, current
Answer: c
Clarification: In a DAC, the input is digital and the output is analog in nature.