Timer

Question 1

An RTC crystal or oscillator allows a CPU to

improve the timing of its ISRs

directly drive its main system clock

provide a signal that can be exactly divided into 1 second

connect to peripherals that also have an RTC

Answer 1

provide a signal that can be exactly divided into 1 second

Question 2

Inside a microcontroller, a “timer” is a/an …

counter that can run down or up.

ISR that is triggered by the RTC

software that implements a stopwatch function.

built-in clock unit.

Answer 2

counter that can run down or up

Question 3

‘A’ must be ___ to make a 40% duty-cycle, if ‘B’ is 30ms. (ensure you include the units too

Answer 3

30/0.4=75ms

Question 4

If ‘B’ is 333ms. What is ‘A’ to make a 40% Duty-Cycle.

666ms

667ms

555ms

832.5ms

Answer 4

832.5ms

Question 5

The count-down timer free-running mode means

Counter counts down to 0 then begins counting up

Counter counts down from maximum to 0 and then stops automatically

Counter wraps back around to maximum after counting down to 0

Counter wraps back around to 0 after hitting a maximum value

Answer 5

Counter wraps back around to maximum after counting down to 0

Question 6

CPU can execute other code while the timer is running concurrently.
True
False

Answer 6

True

Question 7

1. Counter wraps around to the maximum value after counting down to zero.
2. Flag/Interrupt set when the counter wraps around 1st clock edge after zero.

Timer_32 is configured to which mode?

Periodic Timer Mode

Free Running Mode

Continuous Mode

One-shot Mode

Answer 7

Free Running Mode

Question 8

A 1Hz clock is

generated using a counter that counts till 215

used by the Real Time Clock

generated using a crystal that emits a signal at 32.768kHz

directly used as the main clock

Answer 8

generated using a counter that counts till 215

used by the Real Time Clock

generated using a crystal that emits a signal at 32.768kHz

Question 9

A _____ count is used to obtain a 1 second timer from a 30MHz clock?

Answer 9

30000000 (Mega is 10^6)