LED点阵屏上文字显示实验.docx
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LED点阵屏上文字显示实验
LED点阵屏上文字显示实验
李宇pb09013011
实验要求:
在试验板的8×8的LED点阵屏上分别显示“PLD电子技术”。
编程思想:
1.首先定义控制LED点阵屏的端口组a,b,及时钟和复位端口
Port（a:
inoutSTD_LOGIC_VECTOR（7downto0;
b:
inoutSTD_LOGIC_VECTOR（7downto0;
clk:
inSTD_LOGIC;
reset:
inSTD_LOGIC;
2.字的跳变显示是通过改变整型变量m的值来选择扫描的程序段
3.对LED点阵屏的工作方式清楚,XUP板子上采用的是共阴极8x8点阵LED。
8X8点阵LED结构如下图所示
从图中可以看出,8X8点阵共需要64个发光二极管组成,且每个发光二极管是放
置在行线和列线的交叉点上,当对应的某一列置0电平,某一行置0电平,则相应
的二极管就亮;本程序中是通过对行扫描,并对当前行中需要亮灯的列置0来实
现显示过程。
示例程序段如下:
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11101111";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11101111";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11101111";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11101111";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11101111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11101111";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11100011";
b<="11111110";
count<=0;
VHDL代码:
----------------------------------------------------------------------------------
--Company:
--Engineer:
--
--CreateDate:
10:
09:
5805/24/2012
--DesignName:
--ModuleName:
expp8-Behavioral
--ProjectName:
--TargetDevices:
--Toolversions:
--Description:
--Dependencies:
--Revision:
--Revision0.01-FileCreated
--AdditionalComments:
--
----------------------------------------------------------------------------------
libraryIEEE;
----Uncommentthefollowinglibrarydeclarationifinstantiating
----anyXilinxprimitivesinthiscode.
--libraryUNISIM;
entityexpp8is
generic（N:
integer:
=16000;
Port（a:
inoutSTD_LOGIC_VECTOR（7downto0;
b:
inoutSTD_LOGIC_VECTOR（7downto0;
clk:
inSTD_LOGIC;
reset:
inSTD_LOGIC;
endexpp8;
architectureBehavioralofexpp8is
signalcount:
INTEGERRANGE0toN:
=0;--count用来对LED扫描分频用--count1用来产生1HZ的分频信号
signalcount1:
INTEGERRANGE0to49999999:
=0;
signalm:
integer:
=0;--用m的数值来选择该扫描显示那个字
begin
process（reset,clk
begin
--复位时的表现为屏上的灯全部点亮
if（reset='0'then
a<="00000000";
b<="00000000";
count<=0;
m<=0;
count1<=0;
else
if（rising_edge（clkthen
ifcount1=49999999then--一赫兹的分频信号产生
m<=m+1;
count1<=0;
elsecount1<=count1+1;
endif;
--m=0时采用扫描的方式显示第一个字母“P”
ifm=0then
--所选行中点亮的灯的时间为N/8个周期if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11100111";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11101011";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11101011";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11100111";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11101111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11101111";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11101111";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=1时显示“L”,时长同样为1秒
elsifm=1then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11101111";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11101111";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11101111";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11101111";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11101111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11101111";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11100011";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=2显示“D”,时长为一秒elsifm=2then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11100111";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11101011";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11101101";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11101101";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11101101";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11101011";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11100111";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=3显示“电”,时长为一秒elsifm=3then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11101111";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="10000011";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="10000011";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="10000011";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11101111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11101011";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11100011";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=4显示“子”,时长为一秒elsifm=4then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11100011";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11111011";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11000001";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11110111";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11110111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11100111";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11110111";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=5显示“技”,时长为一秒elsifm=5then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11011011";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="10000001";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11000001";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11010101";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="10011111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="10011011";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="11010101";
b<="11111110";
count<=0;
else
count<=count+1;
endif;
--m=6显示“术”,时长为一秒
elsifm=6then
if（count=N/8then
a<="11111111";
b<="01111111";
count<=count+1;
elsif（count=N/4then
a<="11110011";
b<="10111111";
count<=count+1;
elsif（count=3*N/8then
a<="11000001";
b<="11011111";
count<=count+1;
elsif（count=N/2then
a<="11110111";
b<="11101111";
count<=count+1;
elsif（count=N*5/8then
a<="11100011";
b<="11110111";
count<=count+1;
elsif（count=N*3/4then
a<="11110111";
b<="11111011";
count<=count+1;
elsif（count=7*N/8then
a<="11010101";
b<="11111101";
count<=count+1;
elsif（count=Nthen
a<="10110110";
b<="11111110";
count<=0;
m<=0;--一次循环完成,循环计数变量m归零else
count<=count+1;
endif;
endif;
endif;
endif;
endprocess;
endBehavioral;
设计思路:
本实验的目的是要在LED点阵屏上显示字符,基本思想是用扫描的方式使整个屏上需要的灯点亮,并通过计数整型变量m使LED屏上的字每秒钟变换一次,其中扫描频率和m的变化频率都是通过分频实现的。
LED屏的具体扫描方式是这样的:
用向量b每次选通一行,再通过设定向量a选通列,使当前行需要点亮的列被点亮,以合适的频率扫描就可以使需要的字符在LED屏上滚动显示。
心得与收获:
本实验总体上完成的比较顺利,因为对LED的扫描过程在前几个实验都有涉及,但在实验过程中还是遇到了问题,第一次测试时,LED点阵屏在滚动显示完“PLD电子技术”后会有一秒钟在屏上随机显示一个字符,之后才回到对设定字符的循环显示。
经过对代码的反复阅读,终于在计数整型变量m控制的程序段中发现了不妥之处:
原始程序中是在检测到m等于7（即第八个计数时才将m归零,这样导致了LED屏有一秒空闲的时间,并随机点亮屏上的灯。
之后我在扫描显示完“术”之后就将m置零（之前m=6,这样就可以按实验要求完成显示。
升级会员 