The Catholic University of America School of Engineering Department of Electrical Engineering and Computer Science CSC /EE 519 -Summer 2013 June 4th, 2013 Esam El-Araby aly@cua.edu Digital Systems Design Lecture 04 & 05: Logic Design using VHDL
2 •Logical statements in our own language •Truth tables •Boolean algebra expressions •Graphic logic symbols •Timing diagrams Methods to Describe Logic Circuits Boolean Expressions Logic Diagrams Truth Tables Analysis 1 Analysis 2 Design/Synthesis 1 Design/Synthesis 2
3 Some Definitions •Combinational logic circuit –A digital circuit in which logical decisions are made based on: •Current combinations of the inputs (e.g. an adder) •Sequential logic circuit –A digital circuit in which logical decisions are made based on: •The sequence (current and past history) of the inputs (e.g. a memory unit) •Finite state machine (FSM) –A sequential logic circuit that has an internal state –Logical decisions are made based on: •Current combinations of the inputs as well as •The internal state (e.g. a vending machine controller)
4 Finite State Machines (FSM) 1) Moore Machine Inputs Outputs
5 Finite State Machines (FSM) Next State Inputs Outputs State Logic (Combinational Circuit) 1) Moore Machine
6 Finite State Machines (FSM) Memory Elements (Sequential Circuit) Next State Current State Inputs Outputs State Logic (Combinational Circuit) Clock 1) Moore Machine
7 Finite State Machines (FSM) Memory Elements (Sequential Circuit) Next State Current State Inputs Outputs State Logic (Combinational Circuit) Clock 1) Moore Machine
8 Finite State Machines (FSM) Memory Elements (Sequential Circuit) Output Logic (Combinational Circuit) Next State Current State Inputs Outputs State Logic (Combinational Circuit) Clock 1) Moore Machine
9 Finite State Machines (FSM) Statei ______________ Outputsi Statej ______________ Outputsj Inputsk Memory Elements (Sequential Circuit) Output Logic (Combinational Circuit) Next State Current State Inputs…