Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral adapting
Reexamination Certificate
1999-11-02
2003-03-04
Wong, Peter (Department: 2181)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral adapting
C710S069000, C710S015000, C710S266000
Reexamination Certificate
active
06529975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is in the field of computers and signal processing systems and circuits. More particularly, the invention is in the field of addressing a set of devices through a codec.
2. Background Art
Personal computers are used extensively to communicate through a telephone line with a modem. Personal computers are also widely used for receiving or producing audio signals in order to communicate with PC users or for entertainment. To facilitate the handling of audio signals, an audio “codec” is used by in PC's. Also, a modem “codec” is used as part of a typical modem used in PCs. A codec (COder-DECoder) is a circuit that converts analog signals to digital code and vice versa using conversion methods such as PCM (Pulse Code Modulation). A codec typically includes both analog to digital and digital to analog conversion circuits.
FIG. 1
is a prior art diagram illustrating how a codec might be connected to a motherboard and in particular to a controller. Motherboard
110
is a modem PC motherboard. System logic
112
resides on motherboard
110
and is coupled to the remaining components on the motherboard primarily through a PCI (Peripheral Component Interconnect) bus
114
. Controller
116
communicates with system logic
112
through PCI bus
114
. In
FIG. 1
, controller
116
is shown as a stand-alone device. However, controller
116
could be embedded or incorporated into other portions of the PC system including the system logic.
A riser
128
houses other components in FIG.
1
. Riser
128
complies with the industry's standard specification for an Audio/Modem Riser (or “AMR”). The AMR specification defines an industry standard form factor for Audio, Audio/Modem or just Modem risers. The AMR specification defines riser mechanical and electrical requirements for certain systems using what is called an AC-link (“Audio Codec link”) interface as one of the connections between the riser and the motherboard.
Referring to
FIG. 1
, riser
128
includes codec
126
. When riser
128
is plugged into motherboard
110
, codec
126
communicates with controller
116
through AC-link
124
, AMR interface connectors
122
and
120
, and AC-link
118
. Alternatively, the combination of AC-link
124
, AMR interface connectors
122
and
120
, and AC-link
118
can be thought of simply as a single AC-link connecting controller
116
to codec
126
.
Reference is made to
FIG. 2
which shows controller
216
that is coupled to codec
226
through AC-link
218
. Codec
226
includes codec register set
230
. Codec register set
230
is utilized by system and circuit design engineers for various control functions such as for configuring the codec or for setting up the codec to record a certain input such as a CD ROM input. As further examples, the registers in codec register set
230
are used for setting headphone volume, PC beep volume, microphone volume, CD volume, video volume, record gain, 3D control, audio status, audio sample rate control, modem status, modem DAC/ADC level control, GPIO (General Purpose Input/Output) pin configuration, GPIO pin polarity and type, power management, as well as many other codec functions.
Typical codecs, such as those complying with the Intel® AC '97 specification entitled “AC '97 Component Specification,” Revision 2.1, published by Intel® Corporation on May 22, 1998 (or simply “AC '97 specification”), have been designed to perform primarily audio related functions. However, it has become increasingly important for codecs, such as those complying with AC '97 specification, to perform primarily modem related functions. Modem related functions can require additional modules to be controlled by the controller. An example of when an additional module or device and a respective set of registers need to be addressed and controlled through the AC-link is when it is desired to perform a DSP (“Digital Signal Processing”) function, such as acoustic echo cancellation, at a point beyond the AC-link and the codec (as opposed to performing the echo cancellation in the controller itself).
Other examples of additional modules or devices and their respective set of registers that need to be addressed and controlled through the AC-link are an LSD (“Line Side Device”), an SSD (“System Side Device”), and an E-PHY (“Ethernet PHYsical-layer interface”) device. By way of background, an LSD is a module that has been recently devised and added by some manufacturers to a Data Access Arrangement (“DAA”) device in order to facilitate the interfacing of the DAA with a codec. A DAA is a device that is widely used in the art and is conventionally comprised of discrete components used to interface with a telephone line. As stated above, recently, the LSD has been added as a module in the DAA to facilitate interfacing between the DAA and a codec. With the recent addition of the LSD to the DAA by some manufacturers, the DAA is comprised of two main modules which are (a) the discrete component module, and (b) the LSD.
The addition of the LSD to the DAA has resulted in the addition of a module inside the codec to interface with the LSD. The module inside the codec is the SSD. The interface between the LSD which is outside the codec and the SSD which is inside the codec is performed through what is referred to as a Digital Isolation Barrier (“DIB”). The addition of the LSD and the SSD as recent modules that facilitate codec operations and which facilitate the codec interfacing with a telephone line, has given rise to the need to address and control these recently added modules, namely the LSD and the SSD, through the AC-link and the codec. It is noted that an SSD may also be a device separate from (as opposed to integrated in) the codec. An E-PHY is a device that performs Ethernet related functions in a LAN (“Local Area Network”). The E-PHY may be integrated in the codec or, alternatively, the E-PHY may be a device separate from the codec. Each of these modules or devices, i.e. the SSD, LSD, and E-PHY, has a respective set of registers which needs to be addressed and controlled by the controller through the AC-link.
As stated above, in each of the above examples the controller is required to address and control a bank of registers that are accessible to the controller only through the AC-link and the codec. In other words, in order to access devices that are located “beyond” the AC-link, the controller must go through both the AC-link and the codec. As such, the controller must comply with the limitations of the AC-link as well as the limitations of the codec itself. The limitations of the AC-link stem from (a) the limited number of physical wires (or lines) available in the AC-link for communication between the controller and the codec; and (b) a predetermined protocol for AC-link to conduct communications between the controller and the codec. The limitations of the codec stem primarily from the limited number of registers which can by used by a design engineer according to the AC '97 specification for a codec.
The combined limitations of the AC-link and the codec, i.e. the limited number of lines in the AC-link, the predetermined protocol of the AC-link, and the small number of available registers in the codec, make it very difficult, if not impossible, for the design engineer to address and control expansion modules or devices, such as SSD, LSD, and E-PHY, that need to be addressed and controlled by going through the AC-link and the codec.
As regards the small number of available registers in the codec, the AC '97 specification, which is widely used in the industry, is directed to a codec having merely a total of 128 registers, each register being 16-bit wide. However, according to the AC '97 specification, the design engineer is not permitted to address any of the odd-numbered registers in the codec. In fact, according to the AC '97 specification, the codec responds with all 0's to accesses of the odd-numbered registers. Thus, the total number of registers in an AC &apo
Braun David P
Miller Mark E
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