The objective of this post is to describe a cheap rain sensor that can be used to detect rain with microcontrollers such as the Arduino or the ESP8266. Introduction The objective of this post is to describe a cheap rain sensor that can be used to detect rain with microcontrollers such as the Arduino or …
ESP8266: Controlling a LED matrix with the 74HC595 ICs
The objective of this post is to explain how to control the LEDs of a LED matrix using 2 74HC595 ICs and a ESP8266 microcontroller. Introduction The objective of this post is to explain how we can control a LED matrix using 2 74HC595 ICs and a ESP8266. With this method, we will only …
Continue reading "ESP8266: Controlling a LED matrix with the 74HC595 ICs"
ESP8266: Controlling a motor with the ULN2803A
The objective of this post is to explain how to control a motor, including its speed, using an ESP8266 and an ULN2803A integrated circuit. Hardware Since the digital pins of a microcontroller can only source a limited amount of current (in the case of the ESP8266, 12 mA maximum [1]), we can't directly use them …
Continue reading "ESP8266: Controlling a motor with the ULN2803A"
ESP8266: Controlling chained SN74HC595 ICs
The objective of this post is to illustrate how to chain two SN74HC595 ICs and controlling them, using SPI, with the ESP8266. Introduction The objective of this post is to illustrate how to chain two SN74HC595 ICs and controlling them, using SPI, with the ESP8266. Naturally, the working principle is the same for using the shiftOut …
Continue reading "ESP8266: Controlling chained SN74HC595 ICs"
ESP8266: Connection to SN74HC595 via SPI
The objective of this post is to explain how to transfer data between the ESP8266 and the SN74HC595 using the SPI interface. Introduction The objective of this post is to explain how to transfer data between the ESP8266 and the SN74HC595 using the SPI interface. An explanation on how to control some LEDs using this …
ESP8266: Connection to SN74HC595
The objective of this post is to explain how to connect the SN74HC595 8-bit shift register to an ESP8266 to control some LEDs. Introduction The objective of this post is to explain how to connect the SN74HC595 8-bit shift register to an ESP8266 to control some LEDs. The code to interface with the device is …
Buying cheap electronics at Ebay: Part 1
Introduction The objective of this series of posts is to list some electronic components and devices useful for makers and hobbyists that can be bought by very low prices at eBay. Many times, we can find those devices at a much lower price than in many specialized stores, making them affordable to more people. In this particular …
Laws of electronics: KCL
This post describes one of the basic laws of circuit analysis, more precisely KCL (Kirchhoff’s Current Law), which states that the the sum of the currents leaving and entering a node is zero. KCL Kirchhoff's Current Law states that the the sum of the currents leaving and entering a node is zero. We need to take into …
Shorting a voltage source conceptual error
This post describes some conceptual errors with voltage sources, that arise from the definition of voltage source and short circuit. Voltage sources and short circuits As explained in this post, a voltage source imposes a voltage difference across two points, as shown in figure 1. This means that, between points A and B, there is …
Continue reading "Shorting a voltage source conceptual error"
Toggling a LED with Arduino and HC-06
Following the previous post describing the HC-06 module, this one shows how to use it to build a simple program to toggle the debugging LED of an Arduino board, using Bluetooth. This tutorial assumes the use of the HC-06 integrated in the baseboard described in the previous post. Connecting HC-06 to the Arduino Board Using the previously …
techtutorialsx 