About

My hc-sr04 driver on Raspberry Pi 3.

I use a timer to send trigger pulse(10us) every 1 second, and an interrupt handler to monitor the status of echo signal.

The default trigger pin is 27 and echo pin is 17, you can change it easily.

Build

Firstly, you have to get linux header or souce code for rpi, I cloned one from https://github.com/raspberrypi/linux.

Make sure your kernel header version is same as your pi's kernel version, and modify KERNELDIR to your own path in Makefile.

Then type

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

Install module

sudo insmod ./hc-sr04.ko

Enable timer to send trigger signal periodically

echo -n 1 | sudo tee /dev/hc-sr04

Read node to get distance

sudo cat /dev/hc-sr04

The result shows the time difference between various echo signal. Divide it by 58 to get in cm unit.