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：