Sony IR Remote Decoder IC
The Sony IR Decoder IC takes the serial stream of bits from an IR receiver module such as the sharp 58Y or Liteon LTM-97XX series and converts the 12 bit frames of data to straight 8 bit ASCII. The data is converted in a continuous mode, which means the host processor must synchronize with the start bits of the 2400 baud, 8 bit, no parity frames being sent. The Sony IR Decoder is especially suitable for use with controller such as the Basic Stamp and Basic-X microcontroller modules but can also be used with any microcontroller or single board controller with a serial port capability.
A Sony remote control outputs modulated infrared to communicate with a TV set. The IR receiver module demodulates the IR signal and outputs a 12 bit serial word representing the key hit on the remote. The Sony remote control signals have a 2 ms start bit. The Sony Decoder IC watches for the valid start bit and then measures the high time of the each bit of the 12 bit frame. A 700 us wide high portion is a "0" and a 1200us wide high portion is a "1". Holding a remote control button down will cause a continuous stream of the same command word. The Sony Decoder IC will decode each frame and then send the converted byte to the ASCII serial out pin. To avoid false bytes from being output from the decoder, the IC assures that a valid start pulse (2-4 ms low) occurred, that the generated code occurred twice in a row, and that the generated code is found in a look up table in ROM. These checks keep the decoder from outputting bad values and from triggering on noise like sunlight.
The Sony IR Decoder IC will respond to the following keys codes
from a Sony remote control:
|Sony Remote Key||Decoder Output|
|TV - VCR||106|