**ENERGY MANAGMENT SYSTEM USING SIM800L WITH MICROPROCESSOR 8051 FAMILY** ------------------------------------------------------------------------ *Project Components:* at89c51 controller ULN2003A relay driver LM2596 DC-DC converter x2 ![sample][1] 5V DC battery or adaptor 16*2 LCD sim 800l module ![sample][2] Pot 10k 12 MHz crystal Electrolytic capacitors – 1uF (4), 10u Ceramic capacitors – 33pF (2) Resistor – 10k,1k Diode - Led1, 4xNPN diodes. **PROJECT DESCRIPTION** ----------------------- The project aims at a system allowing user to control home based appliances through Sms along with acknowledgements. Here user need not switch home appliances on and off manually. The system allows user to operate these devices through sms, also the status whether the device is switched on or not is sent to user via a return sms. This can be used by domestic users and company users to operate as well as check status of home and company appliances from anywhere in the world. It is a very convenient system for users since it allows them to easily control and monitor these appliances from anywhere. An example is that a person may switch on his House or office AC 15 minutes before he arrives so that he gets a cool environment as soon as he reaches there. The system works in the following manner, the sms sent by user is received by the Gsm receiver and then sent to an 8051 microcontroller in order to process it. The microcontroller then activates the appropriate relay for that appliance and controls it. User may also send an query sms in order to just get the status of an appliance. The query sms is returned to user with the status of that particular appliance. Also user may see all appliance status on an LCD display. **CIRCUIT DESIGN** ------------------ *POWER* In the above circuit, regulated 5Vdc will be fed to the cicuit through PowerPin **J2**. LED **D1** will confirm the status of the cicuit by lighting if the circuit is switched on.The 5V will power the **LCD,MICROCONTOLLER-U1 & LED 1**. By using the **LM2596 DC-DC converter**, the SIM800L module will be supplied **3.8V** through JST connectors **CN1** which will draw 5V from the circuit and the supply 3,8V to **CN2** which is then conneccted to **JP1** in which the SIM800l module will be connected. The second LM2596 DC-DC converter will be to connect to the relays. from CN3 port which draws 5v from the circuit to the dc-dc converter to output **~12V** to run the relays then connects to the **CN4 port**that supplies ~12V to the relay driver **U6-ULN2003A**. LCD (Liquid crystal display) data pins are connected to PORT2 of the controller and control pins RS, RW and EN are connected to the P1.0, P1.1 and P1.2 respectively. Here pot RV1 is used to adjust the contrast of LCD.The LCD will be manually connected to the cirucuit through the Jpins **(J3&J4)**. The **TX,RX** pins of the SIM800l module connect to the **P3** pins of the microcontroller respectively through **10K** resistors. The **IN(1-7)** pins of the **Relay driver-U6** connect to the **P0** pins of the microcontroller. The relays**(3,4,5)** are connected to the **relay driver-U6** through ports OUT(14,13,12). 3 NPN diodes are used across the relays to decouple high voltages to support any 3 loads that will be connceted to the circuit through the 3 CNC ports(X4,X3,X5) rated between 120v~210v. [1]: /editor/20160511/5733382b97d40.jpg [2]: /editor/20160511/57333867652f8.jpg