When the coil is energized, the switch closes, connecting the two contacts together. You could try replacing the relay coil with a 200 ohm resistor to simulate the relay coil to see if the transistor will drive the current. When the microcontroller s output is on, the relay turns on too. This section will help to enable those with limited electronics experience to successfully complete these interfacing tasks. Circuit diagram for relay module interfacing with pic16f877a microcontroller is shown below. If possible, the relay should be powered by a separate power supply to enable a connection of relays requiring a different voltage like for example a 12v relay which is different form the 5v supplied to the microcontroller. If desired, the relay can be powered by a separate power supply, so, for. Dec 10, 2009 i have block diagram of microcontroller with pwm interfacing with relay through relay driver circuit.
Jun 07, 2011 interfacing relay with 8051 slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Relay interfacing with microcontroller using uln2003a the. Microcontroller interfacing with different elements udemy. From mechanical to solid state relays, there are various type of relays are available in. If you continue browsing the site, you agree to the use of cookies on this website. Relay is used in all the home automation projects to control the ac home appliances circuit diagram.
This microcontroller controlled the relay with so efficiently and intelligently. Relay provides isolation between two voltage levels and it is generally use to control ac appliances. Basic code examples are provided for users of the basic stamp or picaxe systems. So by using relay switch we easily turn on or off any high voltage device by microcontroller. The zigbee is a transceiver module constructed with transmitter and receiver. Figure 3 shows how to connect a relay to microcontroller using uln 2003uln 2803. As it can be seen from the above circuit diagram, a uln2003 is connected between the microcontroller and relays in order to drive multiple relays. Relay interfacing with microcontroller 8051 microcontroller. Microcontroller interfacing to relays using uln2003 relay. Nov 23, 2014 interfacing hcsr04 ultrasonic rangefinder with pic 16f877a microcontroller dht11 humidity sensor interface with pic16f877a p10 rg led display interface with stm32f030f4 32bit mcu.
A relay is an electromagnetic switch which is used to switch high voltagecurrent using low power circuits. This attempted to provide a comprehensive introduction to the subject via a single type of microcontroller, which is essentially a complete computer on a chip. Relay is a mechanical device to control high voltage, high current appliances on or off from lower voltage levels. A relay is a switch which is used to switch high voltage or current using low power circuits. When the relay needs to be shut down, microcontroller s output is off.
To interface relay with microcontroller we need a driver circuit to drive the power to relay. Uln2803 is used as a driver for port io lines, drivers output connected to relay modules. Relay module interfacing with pic16f877a microcontroller ac load. Adc interfacing with 8051 microcontroller block diagram by. Oct 21, 2014 when microcontroller makes the output line high binary 1, the transistor is switched on. This circuit is an example of interfacing a relay with a microcontroller using a transistor. Microcontroller may stop working by the negative voltages produced in the relay due to its back emf. A normal bipolar transistor used in switch mode like the bc108 or a darlington pair like the bcx38 can do the job. Transistor is wired as a switch which carries the current required for operation of the relay. This current switches on the relay which in turn switches on the ac load the bulb the diode d1 1n4007 is used as a flyback diode. Relay interfacing with pic microcontroller pic16f877a. Please note that when there is no load, the relay command fully works, without resetting the microcontroller. Relay module interfacing with pic16f877a microcontroller.
Pic microcontrollers can be used as the brain to control a large variety of products. Current flows from the 12v input to the relay and then to the ground via the transistors collector pin. The pic was the first widely available device to use. Microcontroller interfacing techniques document revision. See the block diagram below to how we turn on or off a 230 volt ac bulb by micro controller. In this tutorial im connecting one relay in port b. Interfacing devices with pic microcontroller studentcompanion.
This book is a sequel to my first effort pic microcontrollers, an introduction to microelectronics. Many microcontroller designs typically mix multiple interfacing methods. In both the above circuits, the vdd pin of microcontroller should. It is therefore connected to ouput pins of the microcontroller and used to turn onoff highpower devices such as motors, transformers, heaters, bulbs, antenna systems etc. How to turn on and turn off relay with pic microcontroller by using digital output ports of pic16f877a microcontroller.
Feb 05, 2014 to control our high voltage device like home appliance by pic microcontroller, we have to have clear idea on interfacing relay with pic microcontroller. The zigbee module can be directly interfaced to the microcontroller of rx and tx pins and doesnt require any external middle ware devices. The whole setup is shown in the block daigram of attached file. How to interface relay with pic16f877a pic development board. Explanations of basic commands are provided in the commands section available separately. Interfacing a relay with microcontroller electronics forum. Introduction to the arduino microcontroller handson research in complex systems shanghai jiao tong university june 17 29, 2012 instructor. See the block diagram of driver circuit which i used in my project. In order to control devices, it is necessary to interface or connect them to the pic microcontroller. Relay i am using here is of 12v, i am using this one because its mostly used in projects. Complete circuit for connecting relay with pic microcontroller is given below in the above schematic pic16f877a is used, where on the port b the led and transistor is connected, which is further controlled using the tac switch at rbo. A relay can be easily interfaced with microcontroller using a transistor as shown below.
Apr 24, 2018 interfacing pic microcontroller with st7735r spi tft mikroc projects this post shows how to use mikroc library for st7735r tft with pic16f887 microcontroller where hardware spi module of the pic16f887 is used in this example. Applications of interfacing devices with microcontroller. The transistor is driven into saturation turned on when a logic 1 is written on the port pin thus turning on the relay. May 10, 20 a relay is activated by energizing its coil. Interfacing relay with pic microcontroller using transistor. Relay interfacing with pic microcontroller pic16f877a circuit digest. I have connected a push button with pic microcontroller which will be used to turn on and turn off relay module. Here the heaters are represented with lamps for demonstration purpose. When the pin rb7 of the pic microcontroller goes high, the transistor bc547 turns on and current flows through therelay. Interfacing to the pic microcontroller this section explains how to interface many different input and output devices to the pic microcontroller. I have to choose the appropriate components for circuit design using the requirements mentioned. It should not be directly connected to a pic microcontroller. This book is intended for use in collegelevel courses teaching microcontrollers and embedded systems.
A pic microcontroller is a single integrated circuit small enough to fit in the palm of a hand. Mar 02, 20 interfacing relay with pic microcontroller using transistor. Interfacing relay with pic microcontroller youtube. Interfacing relay to microcontroller dna technology. If you want to know more about relay driver circuit uln2003, relay working and relay interfacing with arduino check these articles. A microcontroller c system can be viewed as a system that reads from inputs, performs processing and writes to outputs. These ics are high voltage, high current darlington transistor arrays with open collector outputs and free. Aug 17, 2017 battery bluetooth board camera circuit clock code computer controller converter devices display hardware interface interfacing lcd led meter microchip microcontroller motor output pcb pic pic12f629 pic12f675 pic16f84 pic16f628 pic16f628a pic16f877 pic16f877a pic18f4550 pic microcontoller pic microcontroller processor programmer proteus. Here i used diode d11n4148ws, resistor r1 1k, transistor t1 bc547, 12 v power supply and 6v relay. Microcontroller interfacing with relay rickeys world.
Pic microcontroller and embedded systems download pdf. Electromechanical relays interfacing circuits with. Microcontroller interfacing with different elements 4. Technically, a relay is an electromagnetic switch that is. If the temperature exceeds the preset value, then microcontroller activates relay that will turn off the heaters and an av alarm will be generated if the system fails. Relay is a combination of the mechanical switch and an electromagnet, it prefers when we want to control a device or machine using the low strength signal.
Before interfacing, every one should know about the relay driver which is used to interface the relay to microcontroller. In this project we will interface a relay with pic microcontroller pic16f877a and control a 220v ac lamp using the relay. The microcontroller will switch on the transistor which in turn will switch on the relay, anything connected to the contacts of the relay can thus be switched on or off. The transistor will be in off state when the when the pin p2. The interfacing circuits can also be used with any pic microcontrollers such. Interfacing of relay with microcontroller aticleworld. Interfacing relays and transistors 64 8255 pc interface card applications manual connecting a spdt relay heavy dc or ac loads a spdt relay typically can handle heavy current loads. Microcontroller boardscontrol the relay operations by using pic16f18f slicker board. Nov 14, 2014 interfacing zigbee module to the microcontroller. There are many reasons for this, including the existence of massive support in both software and hardware by microchip technology. Download pic microcontroller and embedded systems pdf. As the pic microcontroller operates at 5v a potential divider formed from resistors must be used to reduce the pic microcontroller output signal to 1.
Microcontroller interfacing to relays using uln2003, in this article, you will learn how to interface microcontroller to relays using uln2003 relay driver circuit. Interfacing relay with pic microcontroller mikroc electrosome. Microcontrollers are useful to the extent that they communicate with other devices, such as sensors, motors, switches, keypads, displays, memory and. If you want to connect more relays to microcontroller then you can use uln 2003 for connecting seven relays or uln 2803 for connecting eight relays. Actually, we just control the coil portion of relay, so we send the signal to the relay coil. In simple words, we attach any pin of the pic with one pin of relay coil and make the other pin to ground. A relays is an electrical switch that opens and closes under control of another electrical circuit.
Jun 12, 2018 in this project we will interface a relay with pic microcontroller pic16f877a. Microcontroller interfacing circuits revolution revolution education ltd. Programming with pic microcontroller research design lab. Interfacing a relay with pic microcontroller mikroc.
May 21, 2016 relay interfacing relay driver in uln2003 with microcontroller. Jan 23, 2020 the pic 18 is a widely used microcontroller. You can turn on a big ac or dc load such as a home appliance running on 120 vac or big dc motor, by energizing the coil in the same manner as the reed relay. The input is taken from the microcontroller pins and the output corresponding to each input is given to the 5 relays on the output. In this tutorial, we will learn about the interfacing of the relay relay connection with microcontroller and learn how to control a device using the relay. When the pin rb7 of the pic microcontroller goes high, the transistor bc547 turns on and current.
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