Hello friends, I hope you are doing well. In the previous tutorial, we studied the working principle of a relay . Today, we will connect a 12 V relay to a PIC18F4550 microcontroller through a ULN2003A driver. A relay coil needs more voltage and current than a microcontroller pin should provide. It is also an inductive load, so it produces a voltage transient when switched off. The ULN2003A solves these interface problems by providing seven low-side Darlington drivers and seven internal clamp diodes in one package. The key point is that the ULN2003A does not convert a 5 V logic signal into a 12 V output. The 12 V energy comes from a separate 12 V supply. A logic high merely turns on one internal driver, which connects the low side of the relay coil to ground. We will examine that current pa ...
Hello everyone! I hope you are doing well. In this tutorial, we will study the relay from its basic construction to practical selection and control. A relay allows one electrical circuit to operate contacts in another circuit. This makes it useful when a low-power controller must switch a different voltage, a larger load or an electrically isolated circuit. We will focus first on the common electromechanical relay because its moving contacts make the operating principle easy to understand. We will then compare electromagnetic, reed, solid-state, thermal and hybrid relays, calculate coil current, discuss contact ratings and examine a safe microcontroller driver. A relay is often described as an automatic switch, but that short definition hides several important details. The coil and contact ...
Hello friends, I hope you are doing well. In this tutorial, we will build a simple serial terminal in Visual Basic 2010. The application will detect the COM ports available on a Windows computer, open a selected port, transmit text, receive incoming data and close the connection cleanly. This article keeps Visual Basic 2010 because that is the environment used in the original project and screenshots. According to the official Microsoft lifecycle record , Visual Studio 2010 reached the end of support in July 2020, so you should use a supported Visual Studio and .NET version for a new production application. However, the serial communication principles explained here still apply to maintenance work, laboratory computers and older engineering projects. We will begin with the electrical and pr ...
Hello friends! In this tutorial, we will design an LED blinking project using the PIC16F877A microcontroller. It is a simple project, but it introduces several ideas that appear in almost every embedded system: configuring an I/O port, choosing an oscillator, building a reset circuit, calculating LED resistors, generating a time delay, compiling a program, and loading the resulting HEX file into Proteus. We will connect eight LEDs to PORTB and switch the complete port between logic low and logic high. Once this basic version works, you can change the output patterns and timing to create a running light, binary counter, or status display. The important objective is to understand why every connection and every program statement is present. Figure: The original simulation shows the PORTB LED ...
Hello friends! We have already covered the Introduction to XBee Module and Interfacing of XBee with Computer . In this tutorial, we will connect our configured radios to two Arduino UNO Rev3 boards and use a pushbutton on one board to control the built-in LED on the other. We will build the project in stages. First, we will establish the power and serial connections. Next, we will define the messages sent between the boards. Finally, we will write separate sender and receiver sketches and examine how they handle button bounce, incomplete messages, and a lost wireless connection. The example assumes two compatible radios already configured for transparent serial communication at 9600 baud. The address values carried forward from the previous lesson apply to classic S1 802.15.4 firmware. Rad ...
Hello friends! In the previous lesson, we discussed what an XBee module does and how it transfers serial data between devices. Now we will connect two modules to a computer, configure their addresses, and send messages in both directions. This gives us a working radio link before we introduce Arduino code. We will keep the original tutorial's simple addressing exercise: the first module uses address 1111 , and the second uses 2222 . The detailed command example is for classic XBee S1 modules running 802.15.4 firmware. If your module uses Zigbee or DigiMesh, identify it in XCTU and use that firmware's configuration procedure. Matching the case shape does not make these command settings interchangeable. By the end, you should understand the difference between a computer's serial port and a r ...
Hello friends! In this tutorial, we will learn how an XBee module carries data between electronic devices without a signal cable. We will begin with a simple wireless sensor example, identify the hardware and communication settings involved, and then work through the calculations that help us choose a power supply and estimate data capacity. This is the first lesson in our XBee series. After understanding the module, you can follow Interfacing of XBee with Computer to configure two radios, followed by XBee Arduino Interfacing to exchange commands between microcontrollers. The same basic reasoning applies to PIC, STM32, and other controllers with a compatible serial interface. What Is an XBee Module? XBee is a family of wireless communication modules manufactured by Digi International. A mo ...
