Phase 2 -- Logic Implementation & Simulation

Phase 2 -- Logic Implementation & Simulation Switching & Logic Design Project

Overview • Logic Implementation • Translation of Controller to VHDL • Translation of Dataflow to BDF • Simulation • Controller • Dataflow • Controller/Dataflow together

Rule 3 of Design • All designs must have a controller! • And it must be a non-trivial controller (3 or more states). • No excepts permitted.

Translation of Controller to VHDL • State Assignments • Compact NFLIP-FLOP=Log10NumState/Log102 • One-Hot NFLIP-FLOP= NumStates • Add comments w/ Title, Group, Date, & Description • Use enumerated and state names (see handout) • Use CASE statement with embedded IF statements • Use Moore Outputs

Translation of Controller to VHDL • Use a single process design • Place Wait-UNTIL or IF statement with clock at top of process • WAIT UNTIL (clk’event AND clk = ‘1’); • IF(clk’event AND clk = ‘1’) THEN …. END IF;

Warning! • Every IF statement must have an ELSE statement even if there are ELSIF statements. • It is better to specify controller outputs using the conditional assignment statement, then a CASE statement in a process. • Do not write statements that lead to implied latches. That is, make sure that values for all outputs are specified at all times so VHDL does not assume that the present output is the previous output.

Warning! • Remember that the VHDL programs the logic gates in the MAX part that is running in parallel or concurrent. • All signals that are read in a process have to be listed in the sensitivity list, except for the "clock"-process, that is used for implementing registers. In this case, the inputs for the registers should be omitted. • Use parentheses in complex expressions in order to avoid ambiguities.

Warning! • Use one processes for a state machine. • Put outputs in conditional assignment statements. • All synchronous components must use the same global clock. No ripple clocks allowed. • Every VHDL module must have a header specifying title, designers, date, and short description.

Warning! • Don’t assign initial values to signals and variables. • All warnings are bad and good designs have no warnings present.

Add comments --Title: Blackjack Controller --Designer: Dr. James Grover --Date: April 2006 --Description: Controller for Blackjack game. This design --example was based on C.R. Clare's design in Designing Logic --Systems Using State Machines (McGraw Hill, 1972). The blackjack --machine plays the dealer's hand, using typical dealer strategies --to decide whether to draw another card (hit) or stand after --each round. -- --The example contains the following logic designs: -- 1. A State Machine that controls the game logic which include: -- (a) checking the status of the card reader. -- (c) making the decision of what action to take for a hit, -- stand or bust. An example is to draw a card if the -- hit signal is true. -- (b) making the decision of when to use the value 1 or 11 -- for an ace card. . . . . -- adds the value of the drawn card. -- 3. A Binary-to-BCD converter for converting the 5-bit -- binary score and converts it to 2-digit BCD for the -- digital display.

State as Enumerated Types ARCHITECTURE Behavioral OF Controller IS TYPE STATE_TYPE IS (sClear,sShowHit,…) SIGNAL State : STATE_TYPE; SIGNAL Ace, NextAce : BIT; BEGIN

Use Case statements with If Statements FSMLOGIC: PROCESS (Reset,CardIn,IsAce,Ace,CardOut,Hit,Bust,State) BEGIN WAIT UNTIL (CLK’EVENT AND CLK = ‘1’); CASE State IS WHEN sClear => --Reset State NextAce <= '0'; IF Reset = '1' THEN State <= sClear; ELSE State <= sShowHit; END IF; . . . . . END CASE; END PROCESS FSMLOGIC;

Moore Outputs OUTPUT02: WITH State SELECT Sel <= "11" WHEN AddCard, "10" WHEN Add10, "01" WHEN Sub10, "00" WHEN OTHERS;

Dataflow With Title

Random Logic ENTITY Bin2BCD IS PORT ( Tally : IN INTEGER Range 0 to 31; MSD,LSD : OUT BIT_VECTOR(3 DOWNTO 0)); END Bin2BCD;

Random Logic ARCHITECTURE behavioral OF Bin2BCD IS BEGIN Combo01: WITH Tally SELECT LSD <= "0000" WHEN 0, "0001" WHEN 1, "0010" WHEN 2, "0011" WHEN 3, . . . . . "0001" WHEN 31; . . . . . . END Behavioral;

Registers and Adder Tally

Combinational Logic & Display Tally

Dataflow/Controller

Cascade Counters • Use Cnt Enable nor Clk Enable • Use common clock • Use SCLR (synchronous clear)

Cooking Timer • Consider • LPM_COUNTER • LPM_DECODE • LPM_MUX • Hex7Seg • Random Logic

UART (Rx) • LPM_SHIFTREG • LPM_COUNTER • LPM_XOR (for parity if included) • Random Logic

RC Servo and Stepper Motor • LPM_COUNTER • LPM_COMPARE • LPM_CONSTANT • LPM_FF for register • Random Logic • LPM_ADD_SUB for RC Servo

3-Man Rush • LPM_COUNTER (binary or modulo counter) • LPM_SHIFTREG for PRSG (shift register) • LPM_CLSHIFT (barrel shifter) • Random Logic • Hex7Seg

Thermometer • LPM_REG to hold data between Reads • Configure counter as decade or BCD counters BCD

Simulation • Simulate scenario that leads to success • Simulate scenario that leads to fault condition (non success) • Simulate scenario suggested by laboratory assistant or instructor • Simulate and verify simulation

Problems in the past • Timer without state diagram • Digit select on timer display stopped in some states • Did not use three folder/project design • One folder & project for controller • One folder & project for dataflow • One folder & project for dataflow & controller combination

Problems in the past • Did not include LPMs in project • Each counter with different modulo requires new LPM_COUNTER not just new instance of LPM_COUNTER. • Not using common clock causes ripple counter glitches in logic

Implementation Weeks

Phase 2 -- Logic Implementation & Simulation