HC-SR04 is a commonly used ultrasonic sensor which is capable to detect obstacles in a range of 2-300cm. The sensor looks like a small PCB having two metal cylinders on the front-side and a small circuit on the back-side (see Fig.1).
In this article we will provide a simple demo to use HC-SR04. This requires a preliminary read of the sensor user manual:
HC-SR04 User Manual
The sensor has 4 PIN:
VCC, which must be connected to 5V;
Trig, which is an input PIN to trigger the measurement;
Echo, which is an output PIN which sent out a square wave;
GND, which must be continue reading...
Using Infra-Red for remote control is a technology born in the 70’s and after 40 years it is still used because the good ratio performances-costs and low power consumption. IR remote require a line of sight, because of that latest remote includes bluetooth technology.
Today it is possible to buy a small remote and receiving circuitry spending a few dollars. In Embedded system using IR could be a fast and cheap solution for remote control even if nowadays RF, Bluetooth and WiFi modules are very affordable.
Searching documentation for cheap devices is often not easy at continue reading...
The DHT11 is a basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed).
The communication on data pin occurs according to a non-standard protocol known as One-Wire protocol.
In this article we want to provide a demonstration for DHT11 compatible with ChibiOS/HAL 3.0, but also explain concepts inside that demo. Following that purpose we need for the DHT11 datasheet.
Typical circuit requires a continue reading...