HCSR04 is a distance sensor which uses ultrasonic sound waves to to detect distance. As you know I used a HCSR04 ultrasonic sensor with my “Height Measure” robot. With one single HCSR04 was enough for that project. But now I’m working on a new project for disabled people which need two HCSR04 sensor. I had a code with heigh measurament robot. I changed it a little and make extra connections to Arduino. I will publish code when my new project is done. So stay tune and please subscribe my blog and Youtube channel.