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Chapter 5 Register Transfer Languages. Micro-operations RTL RTL specifications Realizing RTL specifications VHDL. Chapter Outline. Specify data transfer Do not specify conditions under which transfers occur Do not specify hardware implementation. Micro-operations. Example: X Y. X.
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Micro-operations RTL RTL specifications Realizing RTL specifications VHDL Chapter Outline
Specify data transfer Do not specify conditions under which transfers occur Do not specify hardware implementation Micro-operations
Specify micro-operations and when they occur Format: conditions: micro-operations Register Transfer Language
α: X Y, Y Z Simultaneous Data Transfers Q D
α: X Y, X Z Invalid Simultaneous Transfers
α: X 0 β: X 1 Loading Constant Values into Registers
α: X Y Multi-bit Data Transfers
Counts up when U = 1 Count sequence: 000 001 010 011 100 101 000 … V is 3-bit output = count value C is 1-bit output = 1 when V = 000 Modulo 6 Counter
Modulo 6 Counter State Table 1 1 1 1 1 1
C = 1 when car is at toll booth I[1..0] indicates coin input Outputs R, G, A: Car in toll booth, toll not fully paid: R = 1 Toll paid: G = 1 Car left without paying full toll: R = 1, A = 1 Toll Booth Controller
Formal syntax – portable Platform independent Design for PLDs, ASICs, or custom chips Simulate designs Different levels of abstraction VHDL – VHSIC Hardware Description Language
Library section Entity section Architecture section VHDL Design Structure
library IEEE; use IEEE.std_logic_1164.all; VHDL Library Section
Modulo 6 counter Designed as a state machine VHDL – High Level of Abstraction
Components Timing Simulation VHDL – Advanced Capabilities