Interface for coupling audio and video equipment to computer

• US 5,077,552 A
• Filed: 08/10/1989
• Issued: 12/31/1991
• Est. Priority Date: 08/10/1989
• Status: Expired due to Fees

• Current Assignee: Mark P. Abbate
• Original Assignee: Mark P. Abbate
• Inventors: Abbate, Mark P.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Magistre, Dervis
• Application Number:
  US07/392,085
• Time in Patent Office: 873 Days
• Field of Search: 340/825.25, 340/825.24, 340/825.22, 340/825.06, 341/55, 341/82, 341/83, 341/95, 379/90, 375/8, 375/9, 375/10, 370/62, 370/15, 455/343
• US Class Current: 341/55
• CPC Class Codes: H04B 1/202 by remote control
• CPC Class Codes: H04L 25/40 Transmitting circuits; Receiving circuits repeater circuits, relay circuits H04L25/20

Abstract

A method and apparatus for encoding data to be transmitted through a RS-422 standard serial interface such that the encoded data approximates one of the Control-L, Control-S wired or Control-S infrared protocols used in some audio and video equipment. Each bit of a data byte to be transmitted to the audio/video equipment is converted into one or more expansion bytes and transmitted at a baud rate such that the encoded bits approximate the shape and size of a bit in the data format of the selected protocol. In the case of Control-L protocol, the receiving port of the RS-422 is coupled directly to the serial interface port of the controlled device while the transmitting port is coupled through a diode to the serial interface port of the controlled device. For Control-S wired protocol, the transmit port of the RS-422 is coupled by an uninterrupted wire to the serial interface port of the controlled device. In Control-S infrared protocol, the transmit port of the RS-422 is coupled to an infrared light emitting diode which translates the data output from the RS-422 into infrared signals which are picked up by an infrared receiver at the controlled device.

Claims

1. A method of encoding digital data bytes from a controlling device for serial transmission through a serial interface port, which serial interface port uses a first protocol, to a controlled device which uses a second protocol, said method comprising the steps of:

encoding each bit of said digital bytes at said controlling device into an expansion byte, each said expansion byte comprising a bit pattern in said first protocol which, when transmitted by said serial interface, emulates the shape of a bit in said second protocol,

transmitting said expansion bytes through said serial interface port in a specified order consistent with said second protocol and at a baud rate at which each expansion byte has a duration equivalent to the duration of a bit in said second protocol.

2. A method as set forth in claim 1 wherein said serial interface port is an RS-422 standard serial interface.

3. A method as set forth in claim 2 wherein each bit of said data bytes that is a logic 1 is converted into an expansion byte comprising consecutive bits of a first logic value and wherein each bit of said data bytes that is a logic 0 is converted into an expansion byte comprising consecutive bits of a second logic value.

4. A method as set forth in claim 3 wherein said controlled device uses Control-L protocol and said expansion bytes comprise eight bits.

5. A method as set forth in claim 4 wherein said controlled device has a baud rate of 9600 and said transmission baud rate is 96,000.

6. A method as set forth in claim 2 wherein said controlled device uses Control-S wired protocol and wherein each bit of said data bytes that is a logic 0 is converted into two bytes of FFH and 00H, respectively, and each bit of said data bytes that is a logic 1 is converted into three bytes of FFH, 00H and 00H, respectively.

7. A method as set forth in claim 6 wherein said baud rate is 16,600.

8. A method as set forth in claim 2 wherein said controlled device uses Control-S infrared protocol and wherein each bit of said data bytes that is a logic 0 is converted into ten consecutive bytes of FFH, FFH, FFH, FFH, FFH, 00H, 00H, 00H, 00H, 00H, respectively, and each bit of said data byte that is a logic 1 is converted into fifteen consecutive bytes of FFH, FFH, FFH, FFH, FFH, 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H, respectively.

9. A method as set forth in claim 8 wherein said baud rate is 80,000.

10. A method of encoding data for transmission from a computer via an RS-422 standard serial interface to a controlled device having a port for Control-L protocol interfacing, said encoding being such that the encoded data emulates the data format of Control-L protocol when transmitted, said method comprising the steps of:

obtaining at said computer a byte of data intended for encoding, said byte comprising individual bits of one of first and second logic values,

encoding each individual bit of said first logic value as eight consecutive bits of said first logic value,

encoding each individual bit of said second logic value as eight consecutive bits of said second logic value,

reversing the order of said encoded bits,

monitoring said port of said controlled device to detect inactivity at said port for a specified period,

after said specified inactive period is detected, monitoring said port of said controlled device at a specified baud rate that is 11-15 times the baud rate of said controlled device in order to detect a start bit transmitted by said controlled device, and

thereafter transmitting said encoded byte via said RS-422 at a baud rate ten times the baud rate of said controlled device,

whereby said transmitted byte emulates a byte of data in Control-L protocol transmitted at said baud rate of said controlled device.

11. A method as set forth in claim 10 wherein the baud rate of said controlled device is 9600, said encoded byte is transmitted at a baud rate of 96,000 and said port of said controlled device is monitored at a baud rate of 130,000.

12. A method of encoding data for transmission from a controlling device via an RS-422 standard serial interface to a controlled device adapted to communicate with other devices via Control-S wired protocol such that the encoded data emulates the data format of the Control-S wired protocol, said method comprising the steps of:

obtaining at said controlling device a byte of data for encoding, said byte comprising individual bits of one of logic zero value and logic one value,

encoding each individual bit of logic zero value as a byte comprising eight consecutive bits of a first logic value followed by a byte comprising eight consecutive bits of a second logic value,

encoding each individual bit of logic zero value as a byte comprising eight consecutive bits of a first logic value followed by a byte comprising eight consecutive bits of a second logic value,

encoding each individual bit of logic one value as a byte comprising eight consecutive bits of said first logic value followed by two bytes each comprising eight consecutive bits of said second logic value,

programming said computer to transmit data at ten times the baud rate of said controlled device,

transmitting four consecutive bytes, each byte comprising eight bits of said first logic value, from said controlling device to said controlled device via an RS-422 standard serial interface,

immediately thereafter, transmitting said encoded byte of data,

whereby said transmitted, encoded byte of data emulates a byte of data in Control-S wired protocol.

13. A method as set forth in claim 12 wherein said controlling device is a computer.

14. A method as set forth in claim 13 wherein said computer is one of an Apple II series computer or Apple Macintosh series computer.

15. A method as set forth in claim 14 wherein said controlled device comprises one of audio or video equipment.

16. A method as set forth in claim 15 wherein said controlled device is a video tape recorder.

17. A method as set forth in claim 16 wherein said first logic value is logic zero and said second logic value is logic one and wherein said bits of said encoded byte are inverted by said RS-422 standard serial interface before transmission.

18. A method as set forth in claim 17 wherein said baud rate of said controlled device is 1,660.

19. A method of encoding data for transmission from a controlling device via an RS-422 standard serial interface to a controlled device adapted to communicate with other devices via Control-S infrared protocol such that said encoded data emulates the data format of the Control-S infrared protocol, said method comprising the steps of:

obtaining at said controlling device a byte of data for encoding, said byte comprising individual bits of one of logic one value and logic zero value,

encoding each individual bit of logic value zero as five consecutive bytes, each of said five bytes comprising eight consecutive bits of logic value one followed by five additional consecutive bytes, each additional byte comprising 10101010,

encoding each individual bit of logic value one as five consecutive bytes, each of said five bytes comprising eight consecutive bits of logic value one followed by ten additional consecutive bytes, each of said additional ten bytes comprising 10101010,

programming said computer to transmit data at a baud rate of approximately fifty times the baud rate of the controlled device,

transmitting, via an RS-422 standard serial interface, twenty consecutive bytes, each byte comprising 10101010,

immediately thereafter, transmitting said encoded byte of data via said RS-422 standard serial interface and an infrared light emitting diode,

whereby said transmitted and encoded byte of data emulates a byte of data in Control-S infrared protocol.

20. A method as set forth in claim 19 wherein said controlling device is a computer.

21. A method as set forth in claim 20 wherein said computer is one of an Apple II series computer or an Apple Macintosh series computer.

22. A method as set forth in claim 21 wherein said controlled device comprises one of audio or video equipment.

23. A method as set forth in claim 22 wherein said controlled device is a video tape recorder.

24. A method as set forth in claim 23 wherein said first logic value is logic one and said second logic value is logic zero and wherein said encoded byte is inverted by said RS-422 standard serial interface.

25. A method as set forth in claim 24 wherein said baud rate of said controlled device is approximately 1660 and said baud rate of said computer is approximately 80,000.

26. An apparatus for encoding and transmitting data from a digital computer to a controlled device via an RS-422 standard serial interface, said controlled device having a single bit serial port for transmitting and receiving data in Control-L protocol, said apparatus comprising:

means for encoding a data byte from said digital computer by changing each bit of said data byte to a coded byte, said coded byte comprising eight consecutive bits of a first logic level, if said bit is a logic one and comprising eight consecutive bits of a second logic level, if said bit is a zero,

wire means coupled between a serial input port of said RS-422 and said port of said controlled device for receiving data transmission from the controlled device,

means for detecting a 1.2 ms break in data transmission from said controlled device,

means for detecting a start bit following said 1.2 ms break in data transmissions,

means for transmitting said encoded data byte to a serial output terminal of said RS-422 standard serial interface at a baud rate ten times the baud rate of the controlled device, and

a diode coupled from said serial output port of said RS-422 for transmitting by infrared light said encoded data to said serial port of said controlled device.

27. An apparatus as set forth in claim 26 wherein said controlled device is a piece of audio or video equipment.

28. An apparatus as set forth in claim 27 wherein the baud rate of said controlled device is 9600.

29. An apparatus as set forth in claim 28 further including means for reversing the order of the bits in the encoded data byte before transmission through said RS-422.

30. An apparatus for encoding and transmitting data from a digital computer to a controlled device via an RS-422 standard interface, said controlled device having a single bit serial port for transmitting data in Control-S wired protocol, said apparatus comprising:

means for encoding a byte of data from said digital computer by changing each bit of said byte having logic value zero to a byte comprising eight consecutive bits of a first logic value followed by a byte comprising eight consecutive bits of a second logic value and changing a bit having logic level one to a byte comprising eight consecutive bits of said first logic value followed by two bytes comprising eight consecutive bits of said second logic value,

means for transmitting said encoded byte to a serial output of said RS-422 standard interface at a preselected baud rate, and

wire means coupling said serial output terminal of said RS-422 standard serial interface to said input terminal of said controlled device.

31. An apparatus as set forth in claim 30 wherein said serial output terminal of said RS-422 standard serial interface inverts the signals which are output through it.

32. An apparatus as set forth in claim 31 wherein said first logic value is logic one and said second value is logic zero.

33. An apparatus for encoding and transmitting data from a digital computer to a controlled device via an RS-422 standard serial interface, said controlled device having a single bit serial port for transmitting and receiving data in Control-S infrared protocol, said apparatus comprising:

means for encoding a byte of data from said digital computer by changing each bit of said byte having logic value zero to a series of 15 consecutive bytes, the first five of which each comprise eight consecutive ones and the last ten of which each comprise logic 10101010 and by changing each bit of said byte having logic value one to ten consecutive bytes, the first five of which each comprise eight consecutive logic ones and the last five of which each comprise bits 10101010,

means for transmitting said encoded bytes to a serial output terminal of said RS-422 standard serial interface at a baud rate of twice the AM carrier frequency of the controlled device,

infrared light emitting diode means coupled between said serial output terminal of said RS-422 and said single bit serial port of said controlled device, for transmitting said encoded bytes via infrared signals, and

means, coupled to said single bit serial port of said controlled device for receiving said infrared signals.

34. An apparatus as set forth in claim 33 further comprising means for reversing the order of the bits in the byte to be transmitted before encoding.

35. An apparatus as set forth in claim 34 wherein said serial output terminal of said RS-422 inverts the logic level of each bit.

36. An apparatus for providing a hardware interface between an RS-422 standard serial interface and a controlled device, said controlled device having a serial interface port and using one of Control-L, Control-S wired and Control-S infrared protocols, said apparatus comprising;

first, second and third ports for coupling to a send data positive port, a receive data positive port and a send data negative port, respectively, of said RS-422 standard serial interface,

fourth, fifth and sixth ports for coupling to the serial interface port of a controlled device using Control-L protocol, Control-S wired protocol and Control-S infrared protocol, respectively,

a diode coupled between said first and fourth ports,

a wire coupled between said second and fourth ports,

an infrared light emitting diode coupled between said third and sixth ports, and

a wire coupled between said third and fifth ports.