buffer to make shifting for the outputs to be exactly 5 volts also to cobble the serial eeprom from the ENC so the ENC can send data and the SEEPROM will ever harm the output and also the ENC cant affect the SEEPROM ,why? This will be shown later. PIC16F877A: powerful controller with (code memory) 64k Flash, 4k ram, 1k eeprom at 5 volts power supply these capabilities serve the ability of processing the TCP/IP stack and also it has 5 I/O ports 12bit ADC with 7 channels we used that controller with a 16Mhz crystal. This IC works on 25 MHz with two power supplies one is the usual one the other on is used as an temporary source when the first supplier is disconnected this IC store the date as a BCD data inside it so when writing or reading to/from it we have to convert the data from BCD to know how to deal with it. 2.2 Wireless connectivity ZigBee (IEEE 802.15.4) is a new global standard for wireless communications providing short-range cost effective networking capabilities that are suitable for applications in the industrial and home automation markets. Such applications require multi-month to multiyear battery life, lower data rates and less complexity than available from existing wireless standards. While there are many technologies and standards previously used in other projects/products, Zigbee is the cutting–edge technology for wireless sensing for at least for the next 10 years. It is the ideal standard to be used for Wireless Home Automation for its power-saving and simplicity characteristics.
7. 2.3 Sensor Network Throughout this project, we have been establishing a Home Automation System using a RF Wireless Sensor Network (WSN). The system has a centralized architecture: Locally, a centralized controller receives information from multiple sensors and, once processed generates the opportune orders for the actuators. User control and monitoring system is established through a web interface that exchanges information with the local controller using the appropriate protocols.