8051 Microcontroller Questions and Answers – Sensor Interfacing

This set of 8051 Micro-controller Multiple Choice Questions & Answers (MCQs) focuses on “Sensor Interfacing”.

1. A thermistor is a __________
a) sensor
b) adc
c) transducer
d) micro controller
View Answer

Answer: c
Explanation: A thermistor is a device which is used to convert the temperature into electrical signals, so it acts as a transducer.

2. What is the difference between LM 34 and LM 35 sensors?
a) one is a sensor and the other is a transducer
b) one’s output voltage corresponds to the Fahrenheit temperature and the other corresponds to the Celsius temperature
c) one is of low precision and the other is of higher precision
d) one requires external calibration and the other doesn’t require it
View Answer

Answer: b
Explanation: LM 34’s output voltage corresponds to the Fahrenheit temperature and LM 35 corresponds to the Celsius temperature.

3. An electronic device which converts physical quantity or energy from one form to another is called ______
a) Sensor
b) Transistor
c) Transducer
d) Thyristor
View Answer

Answer: c
Explanation: An electronic device that converts physical quantity or energy from one form to another is called Transducer. Examples: Sensor, Speaker, Microphone, etc.

4. What is signal conditioning?
a) to analyse any signal
b) conversion or modification is referred to as conditioning
c) conversion from analog to digital is signal conditioning
d) conversion from digital to analog is signal conditioning
View Answer

Answer: b
Explanation: Signal Conditioning is referred to as the conversion of a signal from one form to other, now this may be from analog to digital conditioning or digital to analog conditioning.

5. What steps have to be followed for interfacing a sensor to a microcontroller 8051?
a) make the appropriate connections with the controller, ADC conversion, analyse the results
b) interface sensor with ADC and ADC with 8051
c) interface sensor with the MAX232, send now to microcontroller, analyse the results
d) none of the mentioned
View Answer

Answer: b
Explanation: For interfacing a sensor with an 8051 microcontroller, we need ADC in between because output of sensor is analog and microcontroller works on digital signals only. So whatever signal generated by the sensor is converted into its digital equivalent using ADC and equivalent digital signal is given to the microcontroller for processing.
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6. LM35 has how many pins?
a) 2
b) 1
c) 3
d) 4
View Answer

Answer: c
Explanation: LM35 has 3 pins.
1.Power( +5 Volts )
2.Output analog voltage
3.Ground( 0 Volts )

7. Why Vref is set of ADC0848 to 2.56 V if analog input is connected to the LM35?
a) to set the step size of the sampled input
b) to set the ground for the chip
c) to provide supply to the chip
d) all of the mentioned
View Answer

Answer: a
Explanation: Vref is used to set the step size of the ADC conversion, if it is selected to 2.56 then the step size will be selected to 10mV, so for every step increase of the analog voltage an increase of 10 mV will be there.

Sanfoundry Global Education & Learning Series – Microcontroller.

To practice all areas of Microcontroller, here is complete set of 1000+ Multiple Choice Questions and Answers.


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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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