Home and industrial automation systems abound. IR remote control, Bluetooth home automation, DTMF home automation, Wi-Fi home automation, RF home automation, and voice-controlled home automation. Here's a cheap automation system. It can turn devices on and off at home or in industry. Fig. 1: Block diagram IR remote controllers and receivers use conventional data standards. NEC, PHILIPS RC5, JVC, and SIRC are standard protocols (Sony infrared remote control). This project uses NEC protocol. After understanding IR remote frame format, we'll interface IR receiver TSOP1738 with PIC16F676 to decode NEC remote key presses. Fig. 2 shows how each bit

is sent using pulse distance. Logical '0' is a 562.5s pulse burst followed by a 562.5s gap, taking 1.125ms to broadcast. Logical "1" is a 562.5s pulse burst followed by a 1.6875ms gap, for a total of 2.25ms. When a remote button is pressed, the following message is sent: 1. 9ms pulse lead (16 times the pulse burst length used for a logical data bit) 2. 4.5ms space 3. Receiver's 8-bit address 4. 8-bit address logical inverse 5. Command 8-bit 6. Command's 8-bit logical inverse 7. A 562.5-s pulse burst to cease message transmission. Each byte's least significant bit is supplied first. Fig. 3 shows a NEC IR transmission frame for address 00h (00000000b) and instruction ADh (10101101b). Frame transmission takes 67.5ms. It takes 27ms to send 16 bits of address and command. Controller PIC16F676 Fig. 2: Pin diagram of PIC16F676 Microchip's PIC16F676 is an 8-bit CMOS flash microcontroller. Its 14-pin size and high-performance RISC CPU make it suited for embedded or

industrial automation applications. This little chip includes everything

The PIC16F676's flash memory increases the microcontroller's processing speed. It's available in 14-pin PDIP, SOIC, and TSOP. PIC16F676 has 1.7kB of program memory, 64 bytes of RAM, and 128 bytes of EEPROM. The device's 10-bit ADC has eight analog channels. This module converts analogue sensor values to digital. Device features include power-on reset, comparator, in-circuit serial programming, and master clear reset. These allow it outperform other onboard chips and eliminate the need for external components. Fig. 2 shows PIC16F676 pinout. Working circuit The project uses a PIC16F676 microcontroller and a NEC IR remote to control any AC load, including lights and fans. The microcontroller receives the remote's IR signals for the lights and fans and controls the relays with a relay driver circuit. Relays control lights and fans. In this project, digital IO pins RC0, RC1, and RC2 of Port C of PIC16F676 microcontroller control relays to switch appliances on/off. Programmatically, these pins are outputs. The IR receiver is attached to PIC16F676 input pin RC4. PIC16F676 runs on +5V. The 230V AC mains supply is stepped down with a transformer and rectified with a full-wave rectifier. IC 7805 regulates rectified voltage to +5V. This project is straightforward. When an IR remote button is pressed, it sends 38kHz modulated coded pulses. Microcontroller reads pulses from TSOP 1738 sensor. The microcontroller decodes the

pulse train into hex and compares it to the program's predetermined values. When a key is pressed on an IR remote, the program decodes the delivered IR signal. This project decodes a 32-bit string (4 NEC protocol bytes). The lights/fans software compares the third byte of this 32-bit string. If a match occurs, the controller triggers the respective relay using transistor BC547 and an LED indicates the outcome. The circuit's three LEDs display relay status. IR remote buttons 2, 4, and 6 control three relays. Key 2 toggles RL1, 4 toggles RL2, and 6 toggles RL3. Software The circuit uses PIC16F676's native software. The software is compiled with Mikro C PRO 7.2.0 for PIC and uploaded to PIC16F676. The embedded C language in main.c enables for short coding. PIC K150 programmer board burns hex code onto MCU chip. IR signal is detected without a header, interrupt, or capture and compare mode. RC4 reads data like a push button. When a signal goes high or low, debouncing and the timer start. Time values are recorded in an array whenever the pin changes state. IR remote sends logic 0 as 562.5s and logic 1 as 2250s. The software assumes 562.5's pulse is 0 and 2250's pulse is 1. It's then converted to hex. 32-bit remote signal (4 bytes). Program stores all array bytes and decodes the third to compare. The simple programming statement ‘switch' controls home appliances. Before programming PIC16F676 with PIC K150, set fuse bits. Without fuses, the program won't work.