Method and apparatus for improving serial infrared asynchronous communication performance

• US 5,912,752 A
• Filed: 06/26/1996
• Issued: 06/15/1999
• Est. Priority Date: 06/26/1996
• Status: Expired due to Term

• Current Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: Seo, Toshio, Mollett, Victor Linn, Waldeck, Jason Eric
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US08/670,972
• Time in Patent Office: 1,084 Days
• Field of Search: 359/137, 359/154, 359/152, 359/143, 359/145, 359/110, 359/113, 359/167, 359/174, 359/138, 359/163, 340/825.57, 341/178
• US Class Current: 398/118
• CPC Class Codes: H04B 10/1143 Bidirectional transmission

Abstract

Disclosed is an improved hardware approach for increasing the efficiency of infrared asynchrounous communication performance. By utilizing the Infrared Data Association'"'"'s Serial Infrared Link Access Protocol (IRLAP) along with hardware assist, and DMA associated with most microprocessors, e.g. conventional PC'"'"'s, the processor is free to carry out other functions without having to process the IR communications for both transmit and receive.

Claims

1. Infrared Communication apparatus for machines incorporating at least microprocessor control and including direct memory access means, said machines including a UART and an infrared transmitter and receiver for communicating with other like equipped machines;

said apparatus comprising, in combination;

an IRLAP receive machine for receiving data from said UART and translating said UART received data into data useable by said microprocessor;

said IRLAP receive machine including means for stripping beginning of frame indications from frames after receipt of indications of beginning of frame;

an IRLAP send machine for converting data from said microprocessor into IRLAP data for conveyance to said UART, said IRLAP send machine including means for inserting beginning of frame indications in the frame being transmitted;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction.

2. Infrared Communication apparatus for machines incorporating at least microprocessor control and including direct memory access means, said machines including a UART and an infrared transmitter and receiver for communicating with other like equipped machines;

said apparatus comprising, in combination;

an IRLAP receive machine for receiving data from said UART and translating said UART received data into data useable by said microprocessor;

an IRLAP send machine for converting data from said microprocessor into IRLAP data for conveyance to said UART, said IRLAP send machine including means for inserting beginning of frame indications in the frame being transmitted and said IRLAP including means in said IRLAP send machine providing for a transparency mode to ensure that data values are not confused with flag or control bytes contained in said data elsewhere than where said control of flag bytes are expected in each frame;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction.

3. Infrared Communication apparatus in accordance with claim 2 wherein said flag and control bytes are defined as special reserved bytes, including means in said transparency mode for encoding the occurance of said bytes in other than their expected position in each frame.

4. Infrared Communication apparatus in accordance with claim 3 including means in said IRLAP receive machine for decoding said encoded special reserve bytes to convert the same to data.

5. Infrared Communication apparatus for machines incorporating at least microprocessor control and including direct memory access means, said machines including a UART and an infrared transmitter and receiver for communicating with other like equipped machines;

said apparatus comprising, in combination;

an IRLAP receive machine for receiving data from said UART and translating said UART received data into data useable by said microprocessor;

an IRLAP send machine for converting data from said microprocessor into IRLAP data for conveyance to said UART, said IRLAP send machine including means for inserting end of frame indications in the frame being transmitted;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction;

said apparatus including means for inserting a frame cyclic redundancy checksum prior to sending an end of frame flag.

6. Infrared Communication apparatus for machines incorporating at least microprocessor control and including direct memory access means, said machines including a UART and an infrared transmitter and receiver for communicating with other like equipped machines;

said apparatus comprising, in combination;

an IRLAP receive machine for receiving data from said UART and translating said UART received data into data useable by said microprocessor;

an IRLAP send machine for converting data from said microprocessor into IRLAP data for conveyance to said UART;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction;

wherein said IRLAP frame comprises, in the following order, at least a beginning of frame flag byte;

an address byte;

a command byte;

an information or data byte;

a frame checksum and an end of frame flag byte; and

wherein said flag and control bytes are defined as special reserved bytes, and means, in said send machine, for creating a transparency mode for encoding the occurrence of said special reserved bytes in other than their expected order in each frame.

7. Infrared Communication apparatus in accordance with claim 6 including means in said IRLAP receive machine for decoding said encoded special reserve bytes to convert the same to data.

8. In a personal computer and at least one peripheral device for communicative connection thereto, said personal computer and said peripheral device each including a processor, memory, and direct memory access control, and a UART connected to the processor through a bus and to an infrared transmitter/receiver designed for light path communication between said personal computer and said peripheral device;

wherein said personal computer contains communication hardware assist apparatus for relieving the processor of selected communication tasks externally of said personal computer, to and from said peripheral device, said communication hardware assist apparatus intermediate said processor and said UART and comprising; and

wherein said peripheral device contains communication hardware assist apparatus for relieving the processor of selected communication tasks externally of said peripheral device, to and from said personal computer, said communication hardware assist apparatus intermediate the peripheral processor and the peripheral UART;

an IRLAP receive machine for receiving data sent by infrared from said peripheral to said UART and translating said UART received data into data useable by said processor;

an IRLAP send machine for converting data from said processor into IRLAP data for conveyance to said UART;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction.

9. In a personal computer and at least one peripheral device in accordance with claim 8 wherein said peripheral device includes an IRLAP receive machine for receiving data sent by infrared from said personal computer to said UART of said peripheral device and translating said UART received data into data useable by said peripheral processor, and said communication hardware assist apparatus for relieving the processor of the peripheral device of selected communication tasks externally of said peripheral device, comprising a IRLAP receive machine for receiving data sent by infrared from said personal computer to said UART and translating said UART received data into data useable by said processor of said peripheral device;

an IRLAP send machine for converting data from said processor of said peripheral device into IRLAP data for conveyance to said UART;

said receive and send machines being coupled to said direct memory access means for sending and receiving to and from memory, frames of information with limited peripheral device processor interaction.

11. In a personal computer and at least one peripheral device in accordance with claim 9 including means in said IRLAP receive machine for decoding said encoded special reserve bytes to convert the same to data.

10. In a personal computer and at least one peripheral device for communicative connection thereto, said personal computer including a processor, memory, and direct memory access control, and a UART connected to the processor through a bus and to an infrared transmitter/receiver designed for light path communication with said peripheral device;

and communication hardware assist apparatus for relieving the processor of selected communication tasks externally of said personal computer, to and from said peripheral device, said communication hardware assist apparatus intermediate said processor and said UART and comprising;

an IRLAP receive machine for receiving data sent by infrared from said peripheral to said UART and translating said UART received data into data useable by said processor;

an IRLAP send machine for converting data from said processor into IRLAP data for conveyance to said UART;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction;

wherein an IRLAP frame comprises, in the following order, at least a beginning of frame flag byte;

an address byte;

a command byte;

an information or data byte;

a frame checksum and an end of frame flag byte; and

wherein said flag and control bytes are defined as special reserved bytes, and means, in said machine, for creating a transparency mode for encoding the occurrence of said special reserved bytes in other than their expected order in each frame.

12. In a personal computer and at least one peripheral device in accordance with claim 10 wherein said IRLAP send machine includes means for inserting beginning of frame indications and end of frame indications in the frame being transmitted.

13. In a personal computer and at least one peripheral device for communicative connection thereto, said personal computer including a processor, memory, and direct memory access control, and a UART connected to the processor through a bus and to an infrared transmitter/receiver designed for light path communication with said peripheral device;

and communication hardware assist apparatus for relieving the processor of selected communication tasks externally of said personal computer, to and from said peripheral device, said communication hardware assist apparatus intermediate said processor and said UART and comprising;

an IRLAP receive machine for receiving data sent by infrared from said peripheral to said UART and translating said UART received data into data useable by said processor;

an IRLAP send machine for converting data from said processor into IRLAP data for conveyance to said UART;

said receive and send machines being coupled to said direct memory access means for sending and receiving therefrom frames of information with limited processor interaction;

wherein an IRLAP frame comprises in the following order, at least a beginning of frame flag byte;

an address byte;

a command byte;

an information or data byte;

a frame checksum and an end of frame flag byte; and

wherein said IRLAP send machine includes means for inserting beginning of frame indications and end of frame indications in the frame being transmitted.

14. A method of communication utilizing serial infrared link access protocol (IRLAP) between devices each containing a processor, memory, direct memory access to said memory, and universal asynchronous receiver/transmitters each connected to an infrared receiver/transmitter for sending informational data in the form of frames between at least two of said devices;

said method comprising the steps of;

preparing frames for transmission from one of said devices to another of said devices by;

taking from memory by said direct memory access, informational data to be transmitted;

adding a beginning of frame flag marking the start of a frame;

defining special reserved bytes that if sent as data could be construed by the receiver to be control or flag bytes;

encoding said special reserved bytes when they appear in other than their expected position in each frame so that when transmitted are transparent to the receiver;

adding a frame checksum at the end of informational data being sent, and;

appending an end of frame indication to said frame.

15. A method of communication utilizing serial infrared link access protocol (IRLAP) between devices in accordance with claim 14 including the following steps;

receiving the frame in one of said devices to which said frame was transmitted;

stripping the beginning of frame indication from said received frame,

decoding said encoded special reserved bytes,

insuring data integrity by comparing said checksum to a calculated checksum.

16. A method of communication utilizing serial infrared link access protocol (IRLAP) between devices in accordance with claim 14 including the step of:

storing said informational data into the memory of said device by said direct memory access.

17. A method of communication utilizing serial infrared link access protocol (IRLAP) between devices in accordance with claim 16, including the step of:

stripping said end of frame indication from said frame prior to storage.