IR Remote Controllers and receivers follow standard protocols for sending and receiving the data. Some of the standard protocols are NEC , JVC , SIRC (Sony Infrared Remote Control) etc. We will be discussing only the NEC protocol. After understanding the frame format of IR Remote, We will be interfacing a IR receiver with 8051 and decode the key pressed.

NEC Protocol

NEC IR protocol encodes the keys using a 32bit frame format as shown below.

NEC Frame Format
Address Complement of Address Command Complement of Command
LSB-MSB(0-7) LSB-MSB(8-15) LSB-MSB(16-23) LSB-MSB(24-31)

Each bit is transmitted using the pulse distance as shown below.
Logical '0': A 562.5µs pulse burst followed by a 562.5µs space, with a total transmit time of 1.125ms
Logical '0': A 562.5µs pulse burst followed by a 1.6875ms space, with a total transmit time of 2.25ms

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Schematic 8051 Interfacing Zigbee.JPG Code and Explanation will be updated soon..