Verilog电话计费器的代码

/*信号定义：

clk： 时钟信号，本例中其频率值为1Hz；

decide： 电话局反馈回来的信号，代表话务种类，“01”表示市话，“10”表示 长话，“11”表示特话；

dispmoney： 用来显示卡内余额，其单位为角，这里假定能显示的最大数额为50元（500角）；

disptime： 显示本次通话的时长；

write,read： 当write信号下降沿到来时写卡，当话卡插入，read信号变高时读卡； warn： 余额过少时的告警信号。本例中，当打市话时，余额少于3角，打长 话时，余额少于6角，即会产生告警信号； cut： 当告警时间过长时自动切断通话信号。 */

module account(state,clk,card,decide,disptime,dispmoney, write,read,warn,cut); output write,read,warn,cut; input state,clk,card; input[2:1] decide; output[10:0] dispmoney; output[8:0] disptime; reg[10:0] money; reg[8:0] dtime;

reg warn,cut,write,t1m; //t1m为分时钟 reg set,reset_ena; integer num1,temp;

assign dispmoney=card?money:0; assign disptime=dtime; assign read=card?1:0; always @(posedge clk) begin

if (num1==59) begin num1<=0; t1m<=1; end else begin

if(state) num1<=num1+1; else num1<=0; t1m<=0;

end end

always @(negedge clk) //该进程完成电话计费功能 begin if(!set)

begin money<=11'h500; set<=1; end if(card&state) if(t1m)

case({state,decide}) 3'b101: if(money<3)

begin warn<=1; write<=0; reset_ena<=1; end else

begin //市话计费 if(money[3:0]<4'b0011) begin

money[3:0]<=money[3:0]+7; if(money[7:4]!=0)

money[7:4]<=money[7:4]-1; else

begin money[7:4]<=9; money[10:8]<=money[10:8]-1; end end

else money[3:0]<=money[3:0]-3; write<=1; //市话通话计时 if(dtime[3:0]==9) begin

dtime[3:0]<=0; if(dtime[7:4]==9)

begin dtime[7:4]<=0; dtime[8]<=dtime[8]+1; end else dtime[7:4]<=dtime[7:4]+1; end else begin

dtime[3:0]<=dtime[3:0]+1; warn<=0; reset_ena<=0; end end

3'b110: if(money<6)

begin warn<=1; write<=0; reset_ena<=1; end else begin //通话计时 if(dtime[3:0]==9) begin

dtime[3:0]<=0; if(dtime[7:4]==9)

begin dtime[7:4]<=0; dtime[8]<=dtime[8]+1; end else dtime[7:4]<=dtime[7:4]+1; end

else dtime[3:0]<=dtime[3:0]+1; //长话计费

if(money[3:0]<4'b0110) begin

money[3:0]<=money[3:0]+4; if(!money[7:4])

begin money[7:4]<=9; money[10:8]<=money[10:8]-1; end else money[7:4]<=money[7:4]-1; end

else money[3:0]<=money[3:0]-6; write<=1; reset_ena<=0; warn<=0; end endcase else write<=0;

else begin dtime<=0; warn<=0; write<=0; reset_ena<=0; en //取卡后对一些信号进行复位 end

always @(posedge clk) //该进程在告警时间过长的情况下切断本次通话 begin

if(warn) temp<=temp+1; else temp<=0; if(temp==15)

begin cut<=1; temp<=0; end if(!card||!reset_ena) begin

cut<=0; //复位cut信号 temp<=0;

end end endmodule