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Controlling Infrared Transmission in Local Area Networks

IP.com Disclosure Number: IPCOM000039399D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 4 page(s) / 72K

Publishing Venue

IBM

Related People

Munoz-Bustamante, C: AUTHOR [+3]

Abstract

A technique is described whereby infrared transmission of information, used in local area networks (LAN), is controlled so as to enable peripheral devices associated with computers, such as printers, file servers, keyboards, repeaters, modems, joysticks, etc., to share the same ether during the infrared transmission of data to and from the device. A controller provides the controls needed to enable high-speed or low- speed transmission through infrared light-emitting diodes (LEDs), when there is a high-speed packet transmitting requirement or when there is a low-speed packet transmitting requirement. The controller is unique in that temperature considerations of the LEDs are considered in the transmission of data to and from the various devices.

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Controlling Infrared Transmission in Local Area Networks

A technique is described whereby infrared transmission of information, used in local area networks (LAN), is controlled so as to enable peripheral devices associated with computers, such as printers, file servers, keyboards, repeaters, modems, joysticks, etc., to share the same ether during the infrared transmission of data to and from the device. A controller provides the controls needed to enable high-speed or low- speed transmission through infrared light-emitting diodes (LEDs), when there is a high-speed packet transmitting requirement or when there is a low-speed packet transmitting requirement. The controller is unique in that temperature considerations of the LEDs are considered in the transmission of data to and from the various devices. The ability to control the transmission of information to peripheral devices of various speed ranges and duty cycle through the same ether in LAN packet operation presents distinct problems due to the fact that peripherals requiring high current will cause the transmitting LEDs to become overheated. When this occurs, the light output of the LED is reduced. The circuit described herein essentially provides a duty cycle "cool down" time to the LEDs to prevent overheating,

(Image Omitted)

which in turn improves the packet transmission of data to the various devices with their varying throughput rates. The concept enables the various devices to use the same microcode, thereby eliminating the need to rewrite code for every peripheral device used in the system. The chart in Fig. 1 shows a typical LAN packet operational usage with the number of LEDs, current and duty cycle of each typical peripheral device. Since the current and duty cycle can vary considerably from one device to another, the controller described herein provides a duty cycle "cool down" and transmit time in accordance with its operational requirements. The controller consists of two basic circuits: a gate array circuit, which executes a state machine as a function of a "Hot" signal, and a hot protection circuit, which produces the "Hot" signal. Gate array circuit 10, as shown in Fig. 2, along with firmware, containing the microcode which resides in read-only memory (ROM) unit 11, and "Hot" protection unit 12 provides cool-down timing and interrupt. The ROM contains the state machine so that the controller may execute the following functions as directed by the gate array: - Idle - Inactive operation.

- Media Access - When a device requests transmission

of data, the state machine changes to media access

state so as to permit access to the ether. When

access is granted, the state machine status

changes to transmit mode.

(Image Omitted)

1

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- Transmit - Controls the transmission of the

packet. Under normal operation, the state machine

will return to idle mode after the end of the

packet. However, if a "Hot" signal becomes

present during a packet transmission, the stat...