8 Software TImers

Question 1

What is a software timer?

Answer 1

A softwire timer is a timer that doesn’t use any additional hardware resources, it can be set to one shot or auto-reload. The software timer is implemented int the daemon task.

Question 2

Where is the software timer implemented?

Answer 2

The software task is implemented in the daemon task.

Question 3

When does the software timer use cpu processing time?

Answer 3

The software only uses cpu processing time when the software timer callback function is executing.

Question 4

When will the software callback function execute?

Answer 4

Once the software timer period expires.

Question 5

What is the daemon task?

Answer 5

The daemon task is ran in the kernel on the beginning of the scheduler.

Question 6

How many States does a software timer have?

Answer 6

2, Dormant and Running.

Question 7

Explain the dormant state

Answer 7

Dormant – Software timer exists but isn’t running. State when timer is created (xTimerCreate) or stopped (xTimerStop).

Question 8

Explain the running state

Answer 8

Running – State after starting (xTimerStart), resetting (xTimerReset), or changing timer period (xTimerChangePeriod). Timer callback will execute after the timer period has elapsed.

Question 9

Create a software timer.

Answer 9

xTimerCreate(“OneShot Timer”, pdMS_TO_TICKS(2000), pdFALSE, 0, oneShotTimerCallback)

Question 10

What API calls are there to control a software timer?

Answer 10

xTimerStart() to start the timer.
xTimerStop() to stop the timer.
xTimerReset() to reset the timer.