Browse Prior Art Database

Asynchronous Communication Link for Infrared Transmission

IP.com Disclosure Number: IPCOM000060018D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Connors, BJ: AUTHOR [+2]

Abstract

This article describes an asynchronous communication protocol used relative to an infrared (IR) link which conserves touchpad battery power. The technique described herein is a unique method of transmitting analog data from a remote analog resistive type membrane to a personal computer (PC). Fig. 1 illustrates in block diagram the remote mode. Data is transmitted as asynchronous modulated data. The touchpad transmits with a pulse burst of 40 Khz for 62.5 microseconds inside a bit cell window of 240 microseconds. Presence of the pulse inside the 240-microsecond window determines a mark, while the absence determines a space. The touchpad transmits with odd parity. A microcomputer inside the touchpad does the asynchronous encoding with a bit cell of 240 microseconds.

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Asynchronous Communication Link for Infrared Transmission

This article describes an asynchronous communication protocol used relative to an infrared (IR) link which conserves touchpad battery power. The technique described herein is a unique method of transmitting analog data from a remote analog resistive type membrane to a personal computer (PC). Fig. 1 illustrates in block diagram the remote mode. Data is transmitted as asynchronous modulated data. The touchpad transmits with a pulse burst of 40 Khz for 62.5 microseconds inside a bit cell window of 240 microseconds. Presence of the pulse inside the 240-microsecond window determines a mark, while the absence determines a space. The touchpad transmits with odd parity. A microcomputer inside the touchpad does the asynchronous encoding with a bit cell of 240 microseconds. A logically encoded "1" is transmitted "low" (cable mode) and "IR transmission" (remote mode). A logically encoded "0" is transmitted "high" (cable mode) and "no IR transmission" (remote mode). Fig. 2 illustrates in block diagram the cable mode. Data is transmitted as asynchronous data over the cable. The touchpad transmits a low pulse for 240 microseconds to represent a logical "1", and it transmits a high pulse for 240 microseconds to represent a logical "0". The signal levels on the cable in cable mode are identical to the signal levels on the cable when in remote mode. Therefore, the personal computer does not care if the user is in remote mo...