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1、
LCD12864 是一种单片机常用显示屏，按照其字库共可显示164个英文字母 或者 84个汉字，按数据传输方式具有很多分类。以下为较为常见的8数据线接口的显示教程。
2、
其工作原理是通过驱动RW，RS，E 、8位数据口 来写命令和写数据。在
RW表读“1”、写“0”操作。本次只进行读操作，故RW设为“0”。
E为使能端：高电平写入，故可与clock时钟相同。
RS在写入数据是为“1”。
PSB接高电平
BLK接GND
BLA与接电位器以控制lcd背光亮度
按照单片机使用它的一般工作顺序：指令初始化---->写数据。
3、
首先是指令初始化：下面是其指令表：
首先通过状态机写指令（注意虽然12864指令具有默认值，但还是需要进行配置，否则非正常显示）。首先设置对其功能进行设定，这儿有个坑，刚开始看数据手册没有注意到这点，导致浪费很多时间，此坑如下：
就是对此指令设置，必须要进行两次。一次设置选用的指令集，一次设置控制接口宽度。
随后就是按照指令表内容，设置光标、进入点等。很简单，详见代码
4、
写入数据。
写数据是应将RS设“1”。在写入数据时应注意其行数的选择，其不能自动换行，应进行指令操控换行。本里程使用ST7920字库。其英文字库可以直接使用英文字母如“A”。注意如果现实数值需要加0'd48.
（没有数据手册可以点击后面链接下载，PDF支持Ctr+F查找汉字很是方便：
下载链接：https://download.csdn.net/download/szsfate/10526436）。
使用汉字可以在数据手册自行查找如下：
5、
注意其时钟频率的设定，经实测3KHz左右基本为其最大时钟频率，5k会在指令和数据转换之间出现错误。
6、
以下为其代码：具有详细备注说明。为演示，程序中将data_buf接口注释掉。
/*
* Title: <话机屏幕显示>
* description:
* @author: fateszs
* @data: 2018.7.06
*
*/
module lcd_12864(input clk_50M, input rst,
// input [511:0]data_buf, //使用时去掉注释。output lcd_rs, //寄存器选择输出信号output lcd_rw, //读、写操作选择输出信号output lcd_e, output [7:0]lcd_data); //本实验只做读信号使用 /*其余管脚：PSB接高电平 BLK接GND BLA与接电位器以控制lcd背光亮度 */
//*****************以下为其测试所用数据，使用时删除*****************/wire [511:0]data_buf;assign data_buf[511:504] = 8'hBF;assign data_buf[503:496] = 8'hAA; //开assign data_buf[495:488] = 8'hCA;assign data_buf[487:480] = 8'hBC; //始assign data_buf[31:24] = 8'hBD;assign data_buf[23:16] = 8'hE1; //结assign data_buf[15:8] = 8'hCA;assign data_buf[7:0] = 8'hF8; //束
//***************************************************************///**************************产生lcd时钟信号*************************/reg clk_lcd; reg [16:0]cnt; always @(posedge clk_50M or negedge rst)beginif (!rst)begin cnt <= 17'b0;clk_lcd <= 0;end else if(cnt == 17'd7999) //时钟频率非常重要！！将近3k，经实测5k会在第0位出错。begin cnt <= 17'd0;clk_lcd <= ~clk_lcd;end else cnt <= cnt +1'b1;end//****************************lcd12806控制信号*****************************************/ reg [8:0] state; //State Machine codeparameter IDLE = 4'd0; parameter CMD_WIDTH = 4'd1; //设置数据接口数量parameter CMD_SET = 4'd2; //选择指令集parameter CMD_CURSOR = 4'd3; //设置光标parameter CMD_CLEAR = 4'd4; //清屏parameter CMD_ACCESS = 4'd5; //输入方式设置：数据读写操作后，地址自动加一/画面不动parameter CMD_DDRAM = 4'd6; //DDRAM行地址parameter DATA_WRITE = 4'd7; //数据写入parameter STOP = 4'd8; //reg lcd_rs_r;//输出管教配置assign lcd_rs = lcd_rs_r;assign lcd_rw = 1'b0; assign lcd_e = clk_lcd; //与lcd时钟相同assign lcd_data = lcd_data_r;reg [5:0] cnt_time;reg [7:0] lcd_data_r;reg [7:0] data_buff;always @(posedge clk_lcd , negedge rst)beginif(!rst)beginlcd_rs_r <= 1'b0;state <= IDLE;lcd_data_r <= 8'bzzzzzzzz; //高阻态cnt_time <= 6'd0;endelse begincase(state)IDLE: begin lcd_rs_r <= 1'b0;cnt_time <= 6'd0;state <= CMD_WIDTH;lcd_data_r <= 8'bzzzzzzzz; endCMD_WIDTH: beginlcd_rs_r <= 1'b0;state <= CMD_SET; lcd_data_r <= 8'h30; //8位数据口endCMD_SET:beginlcd_rs_r <= 1'b0;state <= CMD_CURSOR;lcd_data_r <= 8'h30; //基本指令集//同一指令之动作不可同时改变 RE 及 DL ，需先改变 DL 后在改变 RE 才可确保 FLAG 正确设定endCMD_CURSOR:beginlcd_rs_r <= 1'b0;state <= CMD_CLEAR;lcd_data_r <= 8'h0c; // 关光标endCMD_CLEAR:beginlcd_rs_r <= 1'b0;state <= CMD_ACCESS;lcd_data_r <= 8'h01; //清屏endCMD_ACCESS:beginlcd_rs_r <= 1'b0;state <= CMD_DDRAM;lcd_data_r <= 8'h06; //进入点设定endCMD_DDRAM: //行数命令beginlcd_rs_r <= 1'b0;state <= DATA_WRITE;case (cnt_time)6'd0: lcd_data_r <= 8'h80;6'd16: lcd_data_r <= 8'h90;6'd32: lcd_data_r <= 8'h88;6'd48: lcd_data_r <= 8'h98;endcaseendDATA_WRITE: //写数据beginlcd_rs_r <= 1'b1;cnt_time <= cnt_time + 1'b1;lcd_data_r <= data_buff;case (cnt_time)6'd15: state <= CMD_DDRAM;6'd31: state <= CMD_DDRAM;6'd47: state <= CMD_DDRAM;6'd63: state <= STOP;default: state <= DATA_WRITE;endcaseendSTOP:beginlcd_rs_r <= 1'b0;state <= CMD_DDRAM;lcd_data_r <= 8'h80; //从第几行循环cnt_time <= 6'd0;enddefault: state <= IDLE;endcaseendendalways @(cnt_time) begincase (cnt_time)6'd0: data_buff <= data_buf[511:504];6'd1: data_buff <= data_buf[503:496]; //开6'd2: data_buff <= data_buf[495:488];6'd3: data_buff <= data_buf[487:480]; //始6'd4: data_buff <= 8'h20; 6'd5: data_buff <= 8'h20; 6'd6: data_buff <= 8'h20;6'd7: data_buff <= 8'h20; 6'd8: data_buff <= 8'h20;6'd9: data_buff <= 8'h20; 6'd10: data_buff <= 8'h20;6'd11: data_buff <= 8'h20; 6'd12: data_buff <= 8'h20;6'd13: data_buff <= 8'h20; 6'd14: data_buff <= 8'h20;6'd15: data_buff <= 8'h20;6'd16: data_buff <= 8'h20;6'd17: data_buff <= 8'h20;6'd18: data_buff <= 8'h20;//如果显示数字，需要加0'd48,例如data_buff <= num+8'd486'd19: data_buff <= 8'h20;6'd20: data_buff <= "F";6'd21: data_buff <= "A";6'd22: data_buff <= "T";6'd23: data_buff <= "E";6'd24: data_buff <= "S";6'd25: data_buff <= "Z";6'd26: data_buff <= "S";6'd27: data_buff <= 8'h20;6'd28: data_buff <= 8'h20;6'd29: data_buff <= 8'h20;6'd30: data_buff <= 8'h20;6'd31: data_buff <= 8'h20;6'd32: data_buff <= 8'h20;6'd33: data_buff <= 8'h20;6'd34: data_buff <= 8'h20;6'd35: data_buff <= 8'h20;6'd36: data_buff <= 8'h20;6'd37: data_buff <= 8'h20;6'd38: data_buff <= 8'h20;6'd39: data_buff <= 8'h20;6'd40: data_buff <= 8'h20;6'd41: data_buff <= 8'h20;6'd42: data_buff <= 8'h20;6'd43: data_buff <= 8'h20;6'd44: data_buff <= 8'h20;6'd45: data_buff <= 8'h20;6'd46: data_buff <= 8'h20;6'd47: data_buff <= 8'h20;6'd48: data_buff <= 8'h20;6'd49: data_buff <= 8'h20;6'd50: data_buff <= 8'h20;6'd51: data_buff <= 8'h20; 6'd52: data_buff <= 8'h20;6'd53: data_buff <= 8'h20;6'd54: data_buff <= 8'h20;6'd55: data_buff <= 8'h20; 6'd56: data_buff <= 8'h20;6'd57: data_buff <= 8'h20;6'd58: data_buff <= 8'h20;6'd59: data_buff <= 8'h20;6'd60: data_buff <= data_buf[31:24];6'd61: data_buff <= data_buf[23:16]; //结6'd62: data_buff <= data_buf[15:8]; 6'd63: data_buff <= data_buf[7:0]; //束default : data_buff <= 8'h02;endcaseend
endmodule 7/
在DE2FPGA开发板测试如下：
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