Linux device driver for ultrasonic sensor HC-SR04 using device tree
The module works by triggering an ultrasonic pulse, the echo from which then causes an interrupt. Time between the trigger and echo is measured and is used to calculate distance in the following way: uS / 58
Future improvements:
- Trigger and read measurements through a userspace application.
- Another userspace application could be used to regularly trigger measurements and only output when the distance changes from the last reading, resulting in a simple motion sensor.
Raspberry pi pinout can be found here: https://pinout.xyz/
Datasheet for the sensor can be found here: https://www.alldatasheet.com/datasheet-pdf/pdf/1132203/ETC2/HC-SR04.html
TODO: Add diagram
Build using make.
Insert the module with: sudo insmod dt_ultrasonic.ko
Check that the module has been inserted: sudo lsmod | grep dt_ultrasonic
To trigger a measurement use: echo "1" | sudo tee /dev/usnc_device
To read the result of the measurement use: dmesg | grep dt_ultrasonic
To remove the module use: sudo rmmod dt_ultrasonic