Interface for coupling audio and video equipment to computer

DETAILED DESCRIPTION OF THE INVENTION FIG.
3 illustrates the basic concept of the present invention.
A personal computer 20, for example an Apple MacIntosh, includes a central processing unit and a memory, collectively shown at 22.
It also includes serial port hardware 24 which, in the Apple MacIntosh, comprises a Zilog 8530 serial communications controller (SCC) integrated circuit which prepares data for transmission via an RS-422 standard serial interface 26.
The serial port hardware 24 is coupled to the RS-422 standard interface 26 which provides direct serial interfacing with peripheral devices such as audio/video equipment.
In FIG.
3, the interfacing hardware of the present invention is embodied within block 28.
The software is executed within the CPU 22 the serial port hardware 24 and encodes the data to be transmitted into a format which, when transmitted through a RS-422 standard interface, emulates a selected one of three standard protocols used by audio and video equipment; Control-L, Control-S wired or Control-S infrared.
The data is transmitted through a simple hardware interface 28 from the RS-422 port to a piece of audio/video equipment (the controlled device) 30 which comprises interfacing hardware 32 and software for receiving and/or transmitting data in one of the three mentioned protocols.
The audio/video equipment also includes a CPU and memory, collectively shown at 34.
If the logic level voltages of the RS-422 interface are different than the logic level voltages of the controlled device, the interfacing hardware 32 will include voltage translation circuitry for converting the RS-422 interface voltage levels to the voltage levels used in the controlled device.
In the case of the Apple MacIntosh, the RS-422 interface transmits at standard TTL logic levels (logic 0=0 volts and logic 1=5 volts).
The three above-mentioned protocols also use standard TTL logic levels, and, therefore, would not require voltage translation circuitry if the controlling computer is an Apple MacIntosh or other computer using TTL logic levels through an RS-422 standard interface