1. Field of the Invention
The present invention relates to a configurable interface enabling straightforward re-use of a core with different interfaces.
2. Art Background
The latest advances in semiconductor technology and design methodology have enabled the emerging market for System-On-a-Chip (SoC) designs. Full systems, consisting of more than several million logic gates, can now be implemented in a single chip. One of the main design challenges in these SoC designs is the logical and physical interconnect that allows communication between the subsystem cores that compose the design. These cores typically fall into different categories: computing cores such as a CPU (central processing unit), DSP (digital signal processor) or floating point co-processor; peripheral interface cores such as PCI (personal computer interface) or USB (universal serial bus); memory blocks such as SRAM (static random access memory) and on-chip DRAM (dynamic random access memory); and application specific blocks such as video cores (MPEG-motion pictures experts group) or communication cores.
Since many of the SoC designs are targeted towards communications and consumer applications, time-to-market is a critical factor in the decision process on the level of integration to be used in a particular product. Once a core has been proven in one design, it becomes very attractive to re-use the core in later designs. While choosing a proven design may eliminate the time that would otherwise be required to design a new core, design re-use offers the promise of many other benefits. First, a model may be written for the proven core that can provide accurate results when analyzing the requirements and performance of a new system design; the model for a new, unproven core is likely to be neither as accurate as the proven core, nor built in time to influence the design. Second, proven cores can serve as building blocks that simplify the overall design process by allowing the system designer to focus at a higher level of abstraction, while providing improved predictability in the resulting system implementation. Third, re-use of hardware cores protects the investment in software to control those cores, and allows the system software implementation to proceed as soon as the hardware building blocks have been chosen. Finally, core re-use protects the investment in verification and testing. Since the desired systems are highly integrated, the required cores end up deeply embedded within an integrated circuit. In deeply-embedded designs, verifying the design functionality becomes very challenging and testing an individual system to prove that it is correctly built can lead to expensive delays or costly system rework. Thus, maintaining the integrity of core verification and testing is likely the single biggest gain from design re-use.
However, historically, re-using cores has not been efficient. One of the challenges in the re-use of these cores is that, dependent on the system requirements of the SoC that the core is used in, different performance levels and features are required from the core. Moreover, many applications of SoC are targeted towards consumer applications where providing the most cost-effective solution is very important.
The interface of the core has been a source of inefficiency in core re-use.
One option is to re-design the interface of the core. This solution may offer area and performance benefits, but is expensive in term of time, effort and design risk. The effort involved is not only in terms of design time but there is also significant additional work in verification and validation. This solution is represented in
Rather than changing the core, some designers opt to leave the core as is, and adapt the system level interconnect to the existing core interface. While it preserves the integrity of the original core, it leads to many other inefficiencies. With respect to performance, the logic that integrates the core into the system can add latency into the system, which can adversely affect the system performance. With respect to cost, the additional logic can add a significant number of gates to the design and hence increase the chip area and hence the cost. This solution is represented in
The system and method of the present invention provides a core or subsystem with a configurable interface that enables straightforward re-use of the core. In one embodiment, code representative of the core and configurable interface parameters are combined with input consisting of the defined configurable interface parameters to generate a core having an interface configured in accordance with the defined interface parameters.
The objects, features and advantages of the present invention will be apparent from the following detailed description in which:
a, 1b, and 1c illustrate prior art techniques relating to core interfacing.
a and 2b illustrate one embodiment of a logic interface.
a and 3b illustrate embodiments of configurable interface parameters.
In the system and the method of the present invention, the above challenges of creating optimal cores for a particular system are resolved by implementing a core with a highly configurable interface, such that the core together with its interface can be optimally configured for the particular system that the core is used in. In the following description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the present invention. In other instances, well-known electrical structures and circuits are shown in block diagram form in order not to obscure the present invention unnecessarily.
The system and the method of the present invention will be explained by example, initially referring to
In one embodiment, the function to be performed can be specified by the MCmd lines of
In one embodiment, the command encoding can be as given in
The above interface illustrated by
In an exemplary type of configuration, one can configure the width of a particular field. As an example, the width of the address field can be configured to be a value between 1 and 32 lines. This allows the core to be used in systems that require different sizes of address space. This type of configurability is referred to herein as “parametrization”.
In an exemplary second type of configuration, one can select the availability of certain interface functions. In the command-encoding example of
In an exemplary third type of configuration, a signal can be configured to be present or not. This type of configurability is referred to herein as “signal-enabling”.
The greater the configurability of the interface, the wider the usability of the core. One embodiment of an extended and highly configurable core interface is shown in
Some of the extensions illustrated by
One embodiment of a method of generating the optimal core is illustrated in
In one embodiment, the core is implemented as configurable source code that makes use of these parameters or derived versions of these parameters. This source code can be in a variety of forms of e.g. commercially available hardware description languages (Verilog, VHDL) or software languages (C, perl, . . . ), or any combination of these or any other language.
At step 620, the configuration settings are provided. In one embodiment, the configuration settings are defined in a machine-readable form. In one embodiment, the configuration settings for a particular core are defined in a file.
At step 625, the source code and configurations settings are combined, e.g., compiled, to generate the core with the configured interface. In one embodiment, a software program, referred to herein as the core compiler, process, step 625, the configurable source code representation of the core is combined with the data of the configuration to generate a core with the desired interface, step 630.
In one embodiment, the configuration settings can be entered manually by the user; alternatively the settings can be entered through a Graphical User Interface.
The invention has been described in conjunction with the preferred embodiment. It is evident that numerous alternatives, modifications, variations and uses will be apparent to those skilled in the art in light of the foregoing description.
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Number | Date | Country |
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WO 0022553 | Apr 2000 | WO |
WO 0029961 | May 2000 | WO |