7.4. Writing the Ranging Sensor Kernel Module

Try these first

1. 1.

   What does GPIO stand for?

   Hint

   Think about a hardware interface that can change behavior.

2. 2.

   What does a kernel module do?

   Hint

   Recall that it can be loaded and unloaded.

3. 3.

   What is the role of the trigger pin in the ultrasonic sensor?

   • It gets the echo back.
   • It sends out the pulse.
   • It measures distance.

   Hint

   Think about which step comes first in the distance measurement.

4. 4.

   True or False: The distance measured by the ultrasonic sensor can be calculated without considering the time of flight.

   • True
   • False

   Hint

   Recall the formula of distance calculation involving time.

5. 5.

   Write a detailed function that handles measurement of distance, including error checking for timeouts on echo.

   Hint

   Remember to handle time calculation carefully.

6. 6.

   Discuss the implications of not freeing GPIO resources in a kernel module.

   Hint

   Think about resource usage over time and its effects.