Engineering Questions with Answers - Multiple Choice Questions

# MCQs on Timer Programming

1 - Question

What is the clock source for the timers?
a) some external crystal applied to the micro-controller for executing the timer
b) from the crystal applied to the micro-controller
c) through the software
d) through programming

View Answer

Answer: b
Explanation: Timer’s clock source is the crystal that is applied to the controller.

2 - Question

What is the frequency of the clock that is being used as the clock source for the timer?
a) some externally applied frequency f’
b) controller’s crystal frequency f
c) controller’s crystal frequency /12
d) externally applied frequency/12

View Answer

Answer: c
Explanation: The frequency of the clock source for the timer is equal to f/12(where f is the frequency of the crystal).

3 - Question

What is the function of the TMOD register?
a) TMOD register is used to set various operation modes of timer/counter
b) TMOD register is used to load the count of the timer
c) Is the destination or the final register where the result is obtained after the operation of the timer
d) Is used to interrupt the timer

View Answer

Answer: a
Explanation: TMOD is used to set various operation modes of timer/counter by the programmer.

4 - Question

What is the maximum delay that can be generated with the crystal frequency of 22MHz?
a) 2978.9 sec
b) 0.011 msec
c) 11.63 sec
d) 2.97 msec

View Answer

Answer: d
Explanation: For generating the maximum delay we have to multiply the maximum number of counts with the time period required to execute one machine cycle( 65536*1/22MHz).

5 - Question

Auto reload mode is allowed in which mode of the timer?
a) Mode 0
b) Mode 1
c) Mode 2
d) Mode 3

View Answer

Answer: c
Explanation: Auto reload is allowed in the Mode 2 of the timer because here in this mode, we don’t need to load the count again and again in the register.

6 - Question

Find out the roll over value for the timer in Mode 0, Mode 1 and Mode 2?
a) 00FFH,0FFFH,FFFFH
b) 1FFFH,0FFFH,FFFFH
c) 1FFFH,FFFFH,00FFH
d) 1FFFH,00FFH,FFFFH

View Answer

Answer: c
Explanation: For Mode 0 13 bit value is used so 1FFFH is chosen to be the roll over value. Similarly for Mode 1 FFFFH and for Mode 2 FFH is the roll over value for the timers and counter.

7 - Question

What steps are followed when we need to turn on any timer?
a) load the count, start the timer, keep monitoring it, stop the timer
b) load the TMOD register, load the count, start the timer, keep monitoring it, stop the timer
c) load the TMOD register, start the timer, load the count, keep monitoring it, stop the timer
d) none of the mentioned

View Answer

Answer: b
Explanation: When any timer is to turn on, then firstly we have to load the TMOD register and the count. Then the timer is to get started. After then, we need to monitor the timer properly and then when the roll over condition arises then the timer is to be stopped.

8 - Question

If Timer 0 is to be used as a counter, then at what particular pin clock pulse need to be applied?
a) P3.3
b) P3.4
c) P3.5
d) P3.6

View Answer

Answer: b
Explanation: If Timer 0 is to be used as a counter, then a pulse has to be applied at P3.4 and if it is for Timer 1 then the clock pulse has to be applied at the pin P3.5.

9 - Question

In the instruction “MOV TH1,#-3”, what is the value that is being loaded in the TH1 register?
a) 0xFCH
b) 0xFBH
c) 0xFDH
d) 0xFEH

View Answer

Answer: c
Explanation: Negative value is loaded in 2’s complement form. -3 represented in 2’s complement form as FDH.
Steps to convert into 2’s complement:

```3 → 0000 0011       	Binary Equivalent of ‘3’
→  1111 1100          1’s Complement of decimal ‘-3’
→  1111 1101       	2’s Complement of decimal ‘-3’
F     D           Hex Equivalent of ‘-3’```

10 - Question

TF1, TR1, TF0, TR0 bits are of which register?
a) TMOD
b) SCON
c) TCON
d) SMOD

View Answer
Answer: c
Explanation: All of these bits are part of TCON (Timer Control) register. TF0 and TF1 are used to check overflow of timer 0 and timer 1 respectively. TR0 and TR1 are timer control bits used to start and stop of timer 0 and timer 1 respectively.