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SOFTWARE DECODER ALGORITHM FOR INFRARED REMOTE (IR) CONTROL PROTOCOL

IP.com Disclosure Number: IPCOM000033053D
Publication Date: 2004-Nov-23
Document File: 7 page(s) / 24K

Publishing Venue

The IP.com Prior Art Database

Abstract

In an embodiment, a software algorithm for an IR remote control protocol is provided. The output of an IR sensor is set compliment of the input. Hence when IR signal is not present, the output of the IR sensor is Logic High. Whenever the IR sensor receives the first start bit, the output goes low after half bit period. This transition triggers an Interrupt of a Micro controller. An interrupt routine samples the signal at the ¼ th of the bit period. The routine also initiates another timer interrupt that samples the signal on every subsequent half-bit period. Both the samples of every bit are checked whether they are complimentary to each other. Once all the bits are sampled, last 11 bits are decoded for one of 2048 possible keys and the function corresponding to that routine is executed.

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SOFTWARE DECODER ALGORITHM FOR INFRARED REMOTE (IR) CONTROL PROTOCOL

FIELD OF THE INVENTION

[0001]   This invention relates generally to decoder algorithms, and more particularly, to software decoder algorithms for Infrared Remote (IR) control protocol.

BACKGROUND OF THE INVENTION

[0002]    Generally, RC – 5 IR control protocol specifies a free slot that can be used for operating medical devices.  However, conventionally, consumer applications e.g. TV remote controls are not configured for operating medical devices.

[0003]   Thus, there exists a need to configure controls such as, for example, TV and Audio remote controls, for operating medical devices such as an X-ray apparatus.

BRIEF DESCRIPTION OF THE INVENTION

[0004]   In an embodiment, a software algorithm for an IR remote control protocol is provided.  The output of an IR sensor is set compliment of the input. Hence when IR signal is not present, the output of the IR sensor is Logic High.  Whenever the IR sensor receives the first start bit, the output goes low after half bit period.  This transition triggers an Interrupt of a Micro controller.  An interrupt routine samples the signal at the ¼ th of the bit period.  The routine also initiates another timer interrupt that samples the signal on every subsequent half-bit period.  Both the samples of every bit are checked whether they are complimentary to each other. Once all the bits are sampled, last 11 bits are decoded for one of 2048 possible keys and the function corresponding to that routine is executed. 

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]    FIG.1 shows a block diagram of the Infrared (IR) remote control system according to one embodiment of the present invention.

[0006]    FIG. 2 shows a schematic diagram of the bit pattern according to one embodiment of this invention.

[0007]    FIG. 3 shows a flow chart of the software decoder algorithm according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0008]    Various embodiments of this invention describe a software decoder algorithm for an Infrared (IR) remote control protocol. 

[0009]    FIG. 1 shows a block diagram of a remote control system, wherein the system comprises a Remote Control, an Infrared sensor and a Micro controller.  The Infrared sensor receives the incoming Infrared (IR) coded signal from the Remote Control.  The purpose of the Infrared sensor is two fold.  Firstly the sensor senses the incoming IR signal and secondly, it passes the signal through an in-built Bandpass filter and a Schmitt Trigger.

[0010]   For example, the Bandpass filter center frequency is 38 kHz. Thus the output of the sensor is rectangular TTL signal.

[0011]    In an embodiment, the Remote code is 14 bits long with 2 start bits, 1 status bit, 5 system bits and 6 command bits.  The system bits correspond to the 31 possible slots and 6 command bits corresponds to 64 keys. 

[0012]   FIG. 2 shows a bit pattern according to one embodiment of this invention.

[0013...