Interfacing relay to microcontroller dna technology. A relay should not be directly connected to a microcontroller, it needs a driving circuit due to the following reasons. This is a general purpose relay board accepting 8 inputs to drive 8 relays providing control requirement in your project. Relay for interfacing with 8051 microcontroller datasheet. Relays are used where it is necessary to control an electronic circuit by a lowpower signal or where several circuits must be controlled by one signal. The maximum current that a pic microcontroller can source or sink is 25ma while a relay needs about 50100ma current. The overflow blog open source has a funding problem. 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. In the proposed system, the voltage differential relay is only interested in fault voltage levels on the protected line. You can also add for loop so that relay makes a transition continuously many a times.
Often a need arise to interface output of the microcontroller with an electromagnetic relay emr. A relay can be easily interfaced with microcontroller using a transistor as shown below. The relay youve chosen looks about right, and as long as your not switching a huge load it will be fine. In addition, can also use 4 inputs, which are isolated by optocouplers, are queried and monitored. Define function for sending command to the lcd using 8051 a.
Interfacing electromechanical relay with microcontroller. When the pin rb7 of the pic microcontroller goes high, the transistor bc547 turns on and current flows through the relay. Electromechanical relays a relay is an electrically controllable switch widely used in industrial controls, automobiles, and appliances. Mar 02, 20 a relay is activated by energizing its coil. A microcontroller will not able to supply current required for the proper working of a relay. Once the system is set, it controls the input data and observes the resulting effects on the output that relate to the input. This may also damage the device connected to relay so as to avoid. Electromechanical relays interfacing circuits with. Working of relay and its interfacing with 8051 microcontroller. Microcontroller ports provide low source or sink current for more information, refer to microcontroller s datasheet. Interfacing adc 0804 with 8051 microcontroller aticleworld. Interfacing a relay with pic microcontroller mikroc. Pdf implementation of microcontroller based distance relay.
There has to be an interface between industrial electrical devices and a controller, the personal computer pc in this case. Relay concept in 8051 microcontroller and its interfacing by ankur bhardwaj 7. Programming in powerpoint can teach you a few things. Interfacing relay with 8051 using keil c at89c51 electrosome. Applications of interfacing devices with microcontroller. Relay module interfacing with pic16f877a microcontroller ac. A relay is an electrically operated switch or an electromechanical switch.
Robust design using npn transistor to drive each relay. Interface relay with lpc2148 arm7in this tutorial we explain how to interface arm7 lpc2148. Interfacing relay with pic microcontroller using transistor. We use both assembly and c language programs to demonstrate their control. Relay interfacing with pic microcontroller pic16f877a. Aug 12, 2014 sensors and microcontroller interfacing 1. Using switches and relays for automatic or manual modes. The interface used in this work is the computer port interface 2. May 10, 20 a relay should not be directly connected to a microcontroller, it needs a driving circuit due to the following reasons.
Design and construction of a microcontrollerbased mains. The pic16f690 controls all operations that the device does. This section will help to enable those with limited electronics experience to successfully complete these interfacing tasks. Delay using 8051 timers time delay relay electronics hub. Sample program to interface relay with 8051 microcontrollers. Sep 27, 2015 the receiver circuit is similar to the transmitter circuit design and consists of four ics atmel89c51, decoder ht12d, ir receiver tsop1738 and relay driver uln2004. Pic microcontroller pdf downloadable pic18f4550 microcontroller based projects list. Proteus based pic microcontroller projects pdf pic. Relays are devices which allow low power circuits to switch a relatively high currentvoltage onoff. A relay and a contactor have been used as the switching gears to isolate the transformer from the power system in case a fault. This board can also be used as an addon card for the various development board that we provide.
Relay is very important component to interface the heavy appliances with the help of. The relay must work efficiently to trip the circuit breakers if there are faults present. Relay provides isolation between two voltage levels and it is generally use to control ac appliances. Interfacing of relay with microcontroller aticleworld. The purpose of this discussion is to ease the task of designing an interface between the inputs of a microcontroller and a hostile industrial or. Here is a simple microcontrollerrelay interface circuit with perfect galvanic isolation. Digital output interface digital outputs are solenoids, solenoid actuator, relays and indicators. Mar 21, 2019 in this project we will interface a relay with pic microcontroller pic16f877a. The input is taken from the microcontroller pins and the output corresponding to each input is given to the 5 relays. Proteus based pic microcontroller projects pdf list includes projects related to pic microcontroller. To interface relay with microcontroller we need a driver circuit to drive the power to relay. Basic code examples are provided for users of the basic. Get an idea about how to interface dc motor with 8051 microcontroller.
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. Relay contacts in parallel with the original up and down buttons simulate button press. Now, just write the program to make it onoff with delay. Here i used diode d11n4148ws, resistor r1 1k, transistor t1 bc547, 12 v power supply and 6v relay. Then we describe how to interface them to the pic18. Fortunately this is very easy to generate from the microcontroller by using the basic. But, for this purpose the circuit requires relays, acting as controlled switches for different circuits different types of relays are used. From the above equation the value of r3 comes out to be 5. Relays which come in various sizes, ratings, and applications, are used as remote control switches. How to interface relay module with pic16f877a microcontroller.
To control our high voltage device like home appliance by pic microcontroller, we have to have clear idea on interfacing relay with pic microcontroller. So we need to operate relay via transistors switch method. Jun 07, 2011 interfacing relay with 8051 slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. 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. A relays is an electrical switch that opens and closes under control of another electrical circuit.
If desired, the relay can be powered by a separate power supply, so, for. In the circuit provided, the transistor is wired as a switch, which carries the current required for operation of the relay. Suppose we want to operate a relay using microcontroller with the use. Interfacing relay with pic microcontroller youtube. To understand how microcontroller works as a multifunctional relay it is necessary to know about microcontroller working, functions and its applications. Design and implementation of embeddedhuman machine. Generation of time delay is most important concept in embedded systems. Microcontroller based line differential protection for ofc. Interfacing relay with 8051 slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. 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.
You can simulate your programming of microcontroller in proteus 8 simulation software. If you continue browsing the site, you agree to the use of cookies on this website. Pic microcontroller gets the supply from renewable energy and grid. Here the heaters are represented with lamps for demonstration purpose. In order to power specific components of our design, relays will be used to relay. Sensors and microcontroller interfacing slideshare. Relay interfacing using 8051 microcontroller in general, while designing electronics projects the loads are controlled switched on or off using microcontroller block. A current sensor acs712x series has been used in this project as the interfacing instrument between the power transformer and the pic16f690 microcontroller. In this tutorial we will learn relay interfacing with 8051. Oct 21, 2014 so we connect output from our microcontroller pin to the base of transistor. A relay can be easily interfaced with microcontroller using a transistor. The optoisolator led is infrared and will have a forward voltage 1. This current is not enough for driving digital outputs like solenoid, relays and indicators etc.
Interfacing 8051 with relays to drive high power peripherals. In this project we will interface a relay with pic microcontroller pic16f877a and control a 220v ac lamp using the relay. Microcontroller may stop working by the negative voltages produced in the relay due to its back emf. A relay is an electromagnetic switch used to switch high voltage or current using low power circuits and can be interfaced with 8051 using. Interfacing electromechanical relay with microcontroller mcqs with answers 1. Designing the microcontroller interfacing is same as that in the transmitter circuit, specially the reset circuit and oscillator design. This delay using 8051 timers circuit is used in ultrasonic module.
Sensors and microcontroller mohamed albanna all system has an input device, control unit and output device as shown in figure 1. Here we have used 12v relay and connected to the motor. Microcontroller interfacing circuits revolution revolution education ltd. Relay for interfacing with 8051 microcontroller datasheet, cross reference, circuit and application notes in pdf format. Relays are devices which allow low power circuits to switch a relatively high current andor voltage onoff. In this project report description of inputoutput interfacing of microcontroller and the program, which is. So we connect output from our microcontroller pin to the base of transistor. Generally relay coils are designed to operate from a particular voltage often its 5v or 12v. The input is taken from the microcontroller pins and the output corresponding to each input is given to the 5 relays on the output. International journal of engineering trends and technology. Mar 23, 2020 interface of relay with microcontroller. Browse other questions tagged microcontroller relay interface or ask your own question.
Pdf in this project microcontroller 8051 was used for comparisons. For heating feedback an optoisolator is wired in parallel with the original led. Automatic street light control system using microcontroller. Here you can see that output from microcontroller enter transistor via resistor r1 4k7. Pdf design and implementation of electronic control. So if you want to use lm35 temperature sensor to measure temperature with 8051 then you have to interface external adc with 8051 microcontrollers. And we will interface these relays with an 8051 microcontroller.
A relay circuit is typically a smaller switch or device which drives openscloses an electric switch that is capable of carrying much larger current amounts. To interface pic microcontroller with relay, we need to use digital output port of pic 16f877a microcontroller. If you have any questions or droughts feel free to ask here. The avr simulates a usb rs 232 interface and so you can relay card can be easily addressed without problems via a terminal program or other software. The maximum current that a89c51 microcontroller can sink is 15ma while a relay needs about 50 100ma current. In this article, an overcurrent relay is designed based on fuzzy logic control to improve the overall. Adc interfacing with 8051 microcontroller block diagram by. Write the command to the datacommand port of the lcd through our 8051 microcontroller.
Next howto use pwm to generate analog or analogue voltage in digital circuits. As we discussed in above paragraph, voltages are required to turned on the relay module which are normally 5v. Like another microcontroller pic, arduino avr microcontroller etc 8051 microcontroller does not have builtin adc. Pdf design and implementation of electronic control trainer. Interfacing relay to microcontroller relays are devices which allow low power circuits to switch a relatively high currentvoltage onoff. As relays have operating voltages of 6v12v but microcontroller s pin output voltage is 5v so we cant operate relay directly with the microcontroller s pin voltage. Pic was used to monitor the generated power supply and controls relay to provide the supply to load.
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. If desired, the relay can be powered by a separate power supply, so, for instance, 12v solenoids can be controlled by the. Transistor is wired as a switch which carries the current required for operation of the relay. Relay is a mechanical device to control high voltage, high current appliances on or off from lower voltage levels.
Relay interfacing relay driver in uln2003 with microcontroller. When we apply digital high signal to relay, relay becomes on and when we apply digital low signal to relay, relay turns off. This resistor limit the current and only very small current flows from the base to the emitter. Interfacing to the pic microcontroller this section explains how to interface many different input and output devices to the pic microcontroller. To generate 10 khz square wave using 8051 microcontroller. Whenever 8051 microcontroller is turned on initially the controller is in reset state and all the controller pins are high which would result in turning on the relay every time power is turned on or if there is a power fluctuation. Relay interfacing with pic microcontroller pic16f877a circuit digest. See the block diagram of driver circuit which i used in my project. 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 your unsure about the load, then do a simple calculation, for example if your switching a 100w bulb on and off, then 100w divided by 230v about 0. Relay interfacing with microcontroller 8051 microcontroller. By connecting a bulb or led, you can use relay as a switch which turns offon bulb according to the code burnt in microcontroller. Jun 12, 2018 in this project we will interface a relay with pic microcontroller pic16f877a. The steps involved in interfacing an lcd with 8051 1.
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