Lecture 4 - Pulse Width Modulator

Question 1

How many signals can be produced directly and simultaneously by the output compare unit of Timer 1?

Answer 1

Two

OC1A and OC1B

Question 2

On what port are the output compare pins of Timer 1?

Answer 2

Port D
OC1A = D.5
OC1B = D.4

Question 3

What register specifies how output compare pins are changed on a compare match?

Answer 3

TCCR1A

Question 4

How many different operation modes does Timer 1 have?

Answer 4

15

Question 5

What happens in the CTC mode of Timer 1?

Answer 5

Timer 1 is reset to 0 on each compare match, changing output compare pins is possible; timer TOP limit is configurable

Question 6

What happens in the Normal mode of Timer 1?

Answer 6

No compare match event; no change to compare pins; time TOP limit is fixed

Question 7

What registers can be used to specify the TOP limit of Timer 1 in PWM modes?

Answer 7

ICR1 or OCR1A

Question 8

How many output compare interrupts can be triggered by Timer 1?

Answer 8

Two

one by channel A and other by channel B. enabled in register TIMSK

Question 9

If using a prescaler of 1024 how long will it take Timer 1 to increment?

Answer 9

1024us

Question 10

What is the difference between Fast PWM and Phase Correct PWM?

Answer 10

Fast PWM, counter counts to max value then resets to 0.

Phase Correct PWM, counts to max value, then counts back down to zero.

Question 11

What does CTC stand for?

Answer 11

Clear Timer on Compare