3 replies

Human following robot with raspberry pi 4 and H BRIDGE L293D and 2 ultrasound sensors HC-SR05

Hi Devs, I'm building this human following robot with raspberry pi 4 and H BRIDGE L293D and 2 ultrasound sensors HC-SR05
so my colleague asked me put 10k resistor between trig and echo pins for each sensor
My question is.. Why did we implement this resistor, is it for 5v tolerance for raspberry pins or data filtration?? #pcb-and-analog #hardware-design-chat

Solution

Hey putting 10k resistor is not that very necessary here. Raspberry pi gpio operates at 3.3v DC and the Ultrasonic sensor outputs 5v at the ECHO pin that's connected to the Pi. What you need to do is to create a voltage divider circuit here at the ECHO pin so that it will be btw 3v to 3.3v which the Pi can handle. If not there might be damage caused on the gpio of the Pi board.

This also will help you.

https://thepihut.com/blogs/raspberry-pi-tutorials/hc-sr04-ultrasonic-range-sensor-on-the-raspberry-pi

The Pi Hut

HC-SR04 Ultrasonic Range Sensor on the Raspberry Pi

In previous tutorials we've outlined temperature sensing, PIR motion controllers and buttons and switches, all of which can plug directly into the Raspberry Pi's GPIO ports. The HC-SR04 ultrasonic range finder is very simple to use, however the signal it outputs needs to be converted from 5V to 3.3V so as not to damage