This set of 8051 Micro-controller Multiple Choice Questions & Answers (MCQs) focuses on “Sensor Interfacing”.
1. A thermistor is a:
d) micro controller
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
Explanation: LM 34’s output voltage corresponds to the Fahrenheit temperature and LM 35 corresponds to the Celsius temperature.
3. Transducers produce output voltage in the form of?
a) an analog voltage in the form of current
b) an analog voltage in the form of voltage
c) an analog voltage in the form of pressure
d) all of the mentioned
Explanation: Transducers produce output voltage in the form of an analog signal that may be in the form of current, voltage or pressure as the case may be.
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
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 micro controller 8051?
a) make the appropriate connections with the controller, ADC conversion, analyse the results
b) make connections of 8051 with an ADC to convert analog voltage to digital one , send this digital value to the controller, analyse the results
c) interface sensor with the MAX232, send now to micro controller, analyse the results
d) none of the mentioned
Explanation: For interfacing a sensor with 8051 micro controller, firstly it need to be converted into a digital value by connecting it to an ADC converter. Then this digital value is to be send to the micro controller. Now micro controller can examine the results according to the program inbuilt in it.
6. LM35 has how many pins?
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
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 – Micro-controllers.