MSP430 Microcontroller Multiple Choice Questions on “Watchdog Timer”.
1. The watchdog counts up and resets the MSP430 when it reaches the limit?
a) true
b) false
c) cant be said
d) depends on the conditions
Answer: a
Clarification: The watchdog timer is used for the protection of the device. It keeps a track at the counter so that the code doesn’t reach an infinite unending loop. So it actually resets the counter before this particular condition.
2. Which of the following is correct about WDTCTL?
a) it is a 16 bit register
b) it is guided against accidental writes that require a password
c) a reset will occur if a value with an incorrect password is written to WDTCTL
d) all of the mentioned
Answer: d
Clarification: WDTCTL is a 16 bit register that is used for protecting the microcontroller. It actually resets the value when an incorrect password is written to WDTCTL.
3. WDTNMI is found in the _________
a) higher byte of WDTCTL
b) lower byte of WDTCTL
c) its first four bits
d) its last four bits
Answer: b
Clarification: WDTNMI is the fifth bit of the WDTCTL register.
4. Which of the following bits reads 0 under normal conditions but goes 1 when it wants to initiate some action?
a) WDTNMI
b) WDTHOLD
c) WDTTMSEL
d) WDTCNTCL
Answer: d
Clarification: WDTCNTCL is the bit that reads 0 under normal conditions but goes 1 when it wants to initiate some action like resetting the counter.
5. WDTISx bits control the _________
a) period of the clock
b) act as “Nonmaskable Interrupts”
c) stop the watchdog timer
d) start the watchdog timer
Answer: a
Clarification: WDTISx bits of the WDTCTL register is responsible for controlling the period of the clock.
6. The process of setting the WDTCNTCL bit in WDTCTL is through
a) petting
b) feeding
c) kicking
d) all of the mentioned
Answer: d
Clarification: the process of setting the WDTCNTCL bit in the WDTCTL register is by the processes like petting, feeding and kicking.
7. What is the function of this instruction “WDTCTL = WDTPW | WDTCONFIG”, where **#define WDTCONFIG (WDTCNTCL|WDTSSEL)**
a) it sets the watchdog timer
b) it configures and clears the watchdog timer
c) it stops the watchdog timer
d) it configures and sets the watchdog timer
Answer: b
Clarification: WDTCTL = WDTPW | WDTCONFIG instruction is used to clear and configure the watchdog timer of a microcontroller.
8. Is this instruction correct?
WDTCTL_bit.WDTCNTCL = 1;
a) yes
b) no
c) cant be said
d) depends on the conditions
Answer: b
Clarification: No WDTCTL_bit.WDTCNTCL = 1; is an incorrect way of setting the bits of the WDTCTL register because it violates the password protection.
9. Setting the WDTTMSEL bit of the WDTCTL register makes the watchdog timer act as
a) interrupt
b) communication device
c) converter
d) interval timer
Answer: d
Clarification: The WDTTMSEL bit of the WDTCTL register makes the watchdog timer act as the interval timer.
10. WDTIFG flag gets cleared if
a) if is interrupt had occurred
b) if the interrupt is serviced
c) if there can be no interrupt
d) all of the mentioned
Answer: b
Clarification: WDTIFG flag gets cleared if the interrupt is serviced so that again the interrupt can occur.