通过自动售邮票机谈如何设计最优化的状态机.doc

设计一个自动售邮票机。每次只允许投入一枚五角或者一元的硬币，累计投入两元硬币给出一张邮票。如果投入一元五角硬币以后再投入一枚一元硬币，则给出邮票的同时还应找回五角钱第一种设计思路：通过状态机扫描各种给出邮票的情况，按照每次只能投币一次，依据投币的先后顺序。能够给出邮票的有五种情况：l 四个五角硬币。 两个二元硬币。l 三个五角硬币和一个一元硬币（给出邮票同时找回五角）。l 两个五角硬币和一个一元硬币。ll 一个五角硬币和两个一元硬币（给出邮票并找回五角）。设计两个计数器，一个是五角硬币的累加计数，一个是一元硬币的累加计数。每投入一个硬币认为是输入一个脉冲。那么计数器通过各自投入硬币的脉冲沿触发计数。如果累计满两元或者两元五角，那么输出邮票或者输出邮票并找回五角的同时。两个计数器同时清零，清零信号保持一个时钟周期后回复到正常的计数状态。扫描状态机在不断扫描各种情况，每一种状态对应一种给出邮票的情况。若累计不足输出邮票，则输出邮票信号为零，找回五毛信号也为零。LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;USE IEEE.STD_LOGIC_UNSIGNED.ALL;USE IEEE.STD_LOGIC_ARITH.ALL;ENTITY automachine IS PORT ( CLK : IN STD_LOGIC;FIM : IN STD_LOGIC; -五毛硬币ONY : IN STD_LOGIC; -一元硬币RESET:IN STD_LOGIC;STP : OUT STD_LOGIC; -输出邮票BFIM : OUT STD_LOGIC); -找回五毛END ENTITY;ARCHITECTURE behav OF automachine ISSIGNAL FCOUNT : STD_LOGIC_VECTOR(2 DOWNTO 0);SIGNAL OCOUNT : STD_LOGIC_VECTOR(1 DOWNTO 0);SIGNAL MSTATE : STD_LOGIC_VECTOR(4 DOWNTO 0);SIGNAL RETCON : STD_LOGIC;SIGNAL SIG_STP : STD_LOGIC;SIGNAL SIG_BFIM : STD_LOGIC;BEGINPROCESS(RESET,CLK)BEGINIF RESET = 1 THENMSTATE = 10000 ;ELSIF CLKEVENT AND CLK= 1 THENMSTATE(4) = MSTATE(0) ;MSTATE(3 DOWNTO 0) = MSTATE(4 DOWNTO 1) ;END IF ;END PROCESS ;PROCESS(FIM,RETCON,FCOUNT)BEGINIF RETCON = 1 THENFCOUNT = 000 ; ELSIF FIMEVENT AND FIM = 1 THENFCOUNT = FCOUNT + 1 ;ELSE FCOUNT = FCOUNT ;END IF;END PROCESS;PROCESS(ONY,RETCON,OCOUNT)BEGINIF RETCON = 1 THENOCOUNT = 00;ELSIF ONYEVENT AND ONY = 1 THENOCOUNT = OCOUNT + 1 ;ELSEOCOUNT IF FCOUNT = 000 AND OCOUNT = 10 THENSIG_STP = 1;SIG_BFIM = 0;RETCON = 1;ELSESIG_STP = 0;SIG_BFIM = 0;RETCON IF FCOUNT = 001 AND OCOUNT = 10 THENSIG_STP = 1;SIG_BFIM = 1;RETCON = 1;ELSESIG_STP = 0;SIG_BFIM = 0;RETCON IF FCOUNT = 010 AND OCOUNT = 01 THENSIG_STP = 1;SIG_BFIM = 0;RETCON = 1;ELSESIG_STP = 0;SIG_BFIM = 0;RETCON IF FCOUNT = 011 AND OCOUNT = 01 THENSIG_STP = 1;SIG_BFIM = 1;RETCON = 1;ELSESIG_STP = 0;SIG_BFIM = 0;RETCON IF FCOUNT = 100 AND OCOUNT = 00 THENSIG_STP = 1;SIG_BFIM = 0;RETCON = 1;ELSESIG_STP = 0;SIG_BFIM = 0;RETCON NULL;END CASE;END IF;END PROCESS;STP = SIG_STP;BFIM = SIG_BFIM;END BEHAV;通过编译知道：占用硬件逻辑单元为27。并且由于状态机扫描，因此需要较高的时钟频率。第二种实现方法：设投币初始状态为ST0，如果投入一枚五毛硬币为ST1, 如果投入两枚五毛或者投入一枚一元硬币（累计一元）为ST2，如果投入三枚五毛或者一枚五毛和一枚一元（累计一元五角）为ST3，在ST3状态下，如果再次投入一枚五毛硬币，则输出邮票并返回初始状态，如果再次投入一枚一元硬币，则输出邮票并找回五毛同时返回初始状态。ENTITY ATM_REV ISPORT ( RESET : IN STD_LOGIC; -复位信号 CLK : IN STD_LOGIC; -时钟 FCN :IN STD_LOGIC; -投入五角硬币 OCN :IN STD_LOGIC; -投入一元硬币 STP : OUT STD_LOGIC; -给出邮票 BFM : OUT STD_LOGIC); -找回五角END ATM_REV;ARCHITECTURE BEHAV OF ATM_REV IS TYPE ATM_STATE IS (ST0,ST1,ST2,ST3);SIGNAL FCOUNT : STD_LOGIC;SIGNAL OCOUNT : STD_LOGIC;SIGNAL SIG_STP : STD_LOGIC;SIGNAL SIG_BFM : STD_LOGIC;SIGNAL CURRENT_STATE : ATM_STATE;SIGNAL NEXT_STATE : ATM_STATE;BEGINPROCESS(CLK)BEGINIF RISING_EDGE(CLK) THENFCOUNT = FCN;OCOUNT = OCN;END IF;END PROCESS;PROCESS(RESET,CLK)BEGIN IF RESET = 1 THEN CURRENT_STATE = ST0; ELSIF RISING_EDGE(CLK) THEN CURRENT_STATE IF FCOUNT = 1 THEN SIG_STP = 0; SIG_BFM = 0; NEXT_STATE = ST1; ELSIF OCOUNT = 1 THEN SIG_STP = 0; SIG_BFM = 0; NEXT_STATE = ST2; ELSE SIG_STP = 0; SIG_BFM = 0; -RE_COUNT = 0; NEXT_STATE IF FCOUNT = 1 THEN SIG_STP = 0; SIG_BFM = 0; NEXT_STATE = ST2; ELSIF OCOUNT = 1 THENSIG_STP = 0;SIG_BFM = 0;NEXT_STATE = ST3;ELSESIG_STP = 0;SIG_BFM = 0;NEXT_STATE IF FCOUNT = 1 THENSIG_STP = 0;SIG_BFM = 0;NEXT_STATE = ST3;ELSIF OCOUNT = 1 THENSIG_STP = 1;SIG_BFM = 0;NEXT_STATE = ST0;ELSESIG_STP = 0;SIG_BFM = 0;NEXT_STATE IF FCOUNT = 1 THENSIG_STP = 1;SIG_BFM = 0;NEXT_STATE = ST0;ELSIF OCOUNT = 1 THENSIG_STP = 1;SIG_BFM = 1;NEXT_STATE = ST0;ELSESIG_STP = 0;SIG_BFM = 0;NE