![]() Most digital circuits use such time bases, often called “clocks” these circuits and applications are discussed more fully in upcoming projects. Then, your 7SD circuit will be used to drive one and/or two digits on the Blackboard seven-segment display.Ī requirement in this project uses a “time base” circuit to create a regular, recurring periodic signal that can be used to automatically change a circuit’s state (or in this case, select certain signals for use at certain times). In the second requirement, you will create a special decoder called a “Seven Segment Decoder”, or 7SD, that receives a binary number and decodes it into signals that can drive a seven-segment display. Each sub circuit can (and should) be independently verified, so the top-level module verification only needs to confirm the connections between modules. Structural Verilog source files follow the same general methods as the hierarchical design itself – Verilog modules are created for all sub-circuits, and these modules are then “instantiated” and interconnected in a higher-level module using “port mapping” statements. Hierarchical designs are implemented using structural Verilog. Ultimately, experience (and perhaps consultation with others) will guide such choices. ![]() Then, as the design proceeds, adjustments can be made. In these cases, it is typical that several candidate partitions are sketched, pros and cons of each weighed, and the most likely approach pursued further. But sometimes, the choice of where (and why) to partition a design in a certain way is not clear, and no single architecture is obviously the best. Often, these functional boundaries are somewhat obvious, as is the case with the designs presented in this project. In a typical hierarchical design, the first step is to partition the overall design into sub-circuits along functional boundaries. There are many advantages to this “divide and conquer” approach: complex tasks that are divided into simpler tasks are easier to design, document, and debug the simpler sub-circuits can be independently simulated and verified, making it easier to find and fix problems in the higher-level circuit often, the simpler sub-circuits are pre-existing or well-known circuits that can readily and reliably be used the designer can focus on interactions between particular sub-circuits one at a time, rather than trying to address larger numbers of interactions in a larger monolithic circuit the sub-circuits can be stored in a library for future reuse and there are many others. Typically, any design that can be partitioned into simpler building blocks and implemented using a hierarchical design should be built that way.
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