1 / 7

Abstractions in Verilog

f1. a. a. nsel. f. f. f2. b. b. sel. sel. f =. a • sel’ + b • sel. Abstractions in Verilog. Structural Abstraction. module MUX (f, a, b, sel); output f; input a, b, sel; and #5 g1 (f1, a, nsel), g2 (f2, b, sel); or #5 g3 (f, f1, f2); not g4 (nsel, sel); endmodule.

coggin
Download Presentation

Abstractions in Verilog

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. f1 a a nsel f f f2 b b sel sel f = a • sel’ + b • sel Abstractions in Verilog Structural Abstraction module MUX (f, a, b, sel); output f; input a, b, sel; and #5 g1 (f1, a, nsel), g2 (f2, b, sel); or #5 g3 (f, f1, f2); not g4 (nsel, sel); endmodule Structural Description Schematic • Wires are used for connectivity

  2. f1 a a nsel f f f2 b b sel sel f = a • sel’ + b • sel Behavioral Abstraction module MUX (f, sel, b, c); output reg f; input sel, a, b; always @ (sel or a or b) begin if (sel == 1) f = a; else f = b; end endmodule • Sequential statements • Registers are assigned • Word-level arithmetic can be used

  3. f1 a a nsel f f f2 b b sel sel f = a • sel’ + b • sel Dataflow Abstraction module MUX (f, sel, a, b); output reg f; input sel, a, b; wire nsel, f1, f2; assign nsel <= ~sel; assign f1 <= a && nsel; assign f2 <= b && sel; assign f <= f1 || f2; endmodule • Continuous assignment statement • Can only assign wires, not registers • Assign is evaluated whenever the righthand side changes • Not allowed inside process blocks

  4. State Machine Abstractions • Moore machine - output is determined by state, not input • Sequential design - contains flip-flops (2)

  5. Behavioral Description, State Machine • One block defines state transitions, one defines outputs, one updates ffs

  6. Moore Machine Structure • Structural design - combinational logic + flip-flops • State update logic + output logic

  7. Moore Machine Structure

More Related