As part of my robot project I need a small microcontroller to do som basic task like measuring distance using a HR-SR04 sensor. I plan to use a raspberry pi as main controller for that robot and as is runs a linux kernel is is not realtime and might be inaccurate for this application. The goal is to have the microcontroller send the measured distance over i2c to the raspberry pi.
The Ultrasonic module works as explained in the following diagram:
Lot’s of different examples regarding the HR-SR04 and microcontrollers can be found on the internet. Unfortunately a lot of them are incomplete or contain bad code. So here is yet another example 🙂
Below you can find a very basic schema with a attiny2313, the HR-SR04, an ISP connector and a led with a resistor.