Lesson 6

Question 1

Implementing time measurement in embedded systems requires the use of a _____________________ to measure
the time.

Answer 1

Timer or Counter

Question 2

a digital waveform characterized by alternating between two voltage
levels, typically high (logic 1) and low (logic 0).

Answer 2

Square Wave

Question 3

timers that are of low resolution
These are mainly used to generate time in a readable format for humans.
It functions as a digital watch, used to tell the time to the user.

Answer 3

Real-Time Clock (RTC)

Question 4

is an indication that a device needs attention. As long as it needs
attention, the line is asserted.

Answer 4

Level triggered interrupt

Question 5

This kind of timer is a programmable one. It provides an output signal when it starts and ends in a programmable count. The output signal might cause an interrupt to occur.

It is programmed with intervals that are fixed. This interval helps in finding the amount of
time it will take to provide the necessary signal.

Answer 5

Interval Timer

Question 6

the microcontroller completes the execution of the current instruction and
starts the execution of an __________________

Answer 6

ISR (Interrupt Service Routine)

Question 7

a technique used to generate analog-like signals using digital output pins. It involves rapidly switching a signal on and off at a fixed frequency.

is commonly used to control the speed of motors and the brightness of
LEDs by varying the duty cycle of a square wave signal.

Answer 7

Pulse-Width Modulation (PWM)

Question 8

are low level programming concept, extremely important, and irreplaceable.

Answer 8

Interrupts

Question 9

plays the role of time elapsed measurement. It starts it counting from zero and goes
upward in a gradual manner.

Answer 9

Stopwatch

Question 10

caused either by an exceptional condition or a special instruction in the instruction set which causes an interrupt when it is executed by the processor.

Answer 10

Software Interrupts

Question 11

These interrupts are more reliable and accurate, as they are not affected by execution time.

Answer 11

Hardware Interrupts

Question 12

After every clock period, the timer is incremented by 1 (or reset to 0 in case it is at maximum value). Before incrementing, the value of the timer is compared to OCR. This interrupt is called _____________

Answer 12

Compare Match Interrupt

Question 13

Simple method of obtaining analog output of any value between 0 and 5V.

Answer 13

PWM (Pulse Width Modulation) Mode

Question 14

Timer starts at 0 as usual, but instead of resetting after maximum value, it resets after reaching value specified in OCR register.

Answer 14

CTC Mode

Question 15

These can only be used for operating in a single mode (periodic and decrementing).These are then used in multitasking and context switching. It can easily provide time delays.

Answer 15

Systick Timer

Question 16

is an event notification. When some particular thing happens, the
device generates an active edge on the interrupt line.

Answer 16

Edge triggered interrupt

Question 17

A device, which counts the input at regular interval (δT) using clock pulses at its input.

Answer 17

Timer

Question 18

an analog waveform that smoothly varies between positive and negative
voltage levels.

Answer 18

Sine Wave

Question 19

Timer starts at 0, goes to maximum value and then resets itself. OVERFLOW and
COMPARE MATCH interrupts generated as normal.

Answer 19

Normal Mode

Question 20

The table of memory locations set aside to hold the addresses of ISRs

Answer 20

Interrupt Vector Table

Question 21

a high-priority interrupt can interrupt a low-priority interrupt. This is known as ______________

Answer 21

interrupt inside interrupt.

Question 22

the process of measuring the time it takes for a specific event to occur in an
embedded system. Its purpose is to ensure that the system is operating within the required time constraints.

Answer 22

Time measurement

Question 23

a device that is present in the embedded systems. If the system detects
any malfunction while it is operating in its normal manner, the timer immediately works on solving the problem.

can detect errors like program errors, code crashes, the software hang, and even power surges. It can immediately detect system malfunctions.

Answer 23

Watchdog Timer

Question 24

The process of generating analog signals in an embedded system. The purpose of this is to produce a specific signal that meets the requirements of the
device being controlled.

Answer 24

Waveform Generation

Question 25

In response to the interrupt, a routine or program (called _____________), which is running presently interrupts and an interrupt service routine (ISR)
executes.

Answer 25

foreground program

Question 26

The microcontroller keeps checking the status
of other devices; and while doing so, it does no other operation and consumes all its processing time for monitoring.

Answer 26

Polling

Question 27

register is responsible for enabling and disabling the interrupt.

Answer 27

IE (interrupt enable)

Question 28

A device, which counts the input due to the events at irregular or regular intervals.

Answer 28

Counter

Question 29

When an interrupt gets active, the microcontroller goes through the following steps.

Answer 29

1. The microcontroller closes the currently executing instruction and saves the address of the next instruction (PC) on the stack.
2. It also saves the current status of all the interrupts internally (i.e., not on the stack).
3. It jumps to the memory location of the interrupt vector table that holds the address of the interrupts service routine.
4. The microcontroller gets the address of the ISR from the interrupt vector table and jumps to it. It starts to execute the interrupt service subroutine, which is RETI (return from interrupt).
5. Upon executing the RETI instruction, the microcontroller returns to the location where it was interrupted. First, it gets the program counter (PC) address from the stack by popping the top bytes of the stack into the PC. Then, it start to execute from that address.

Question 30

are signals generated by a timer or a counter that occur at regular intervals. These
interrupts are used to trigger specific actions in an embedded system, such as updating a display or reading
a sensor.

Answer 30

Periodic interrupts

Question 31

involves accurately measuring time intervals, often in
microseconds or nanoseconds, depending on the application’s requirements.

Answer 31

Time Measurement

Question 32

These are basic timers that you can use for various purposes, including starting a device or measuring the time duration.

In the case of robots assembling, this timer is very helpful in getting the work done
successfully.

Answer 32

General Purpose Timer

Question 33

Interrupt means _________

Answer 33

event

Question 34

is generated when a timer tries to exceed its maximum value and resets to 0. The name is derived from the fact that the timer has “overflowed” its limit.

Answer 34

Overflow/Overflow Interrupt