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【从零开始走进FPGA】 LCD 1602 Hello World

前面说过,在C,C++等语言学习中,“Hello World”将会是第一个学习的代码,但是在FPGA中由于电路驱动的复杂性,与单片机雷同,我们无法在电脑上实现“

  前面说过,在C,C++等言语学习中,“Hello World”将会是第一个学习的代码,但是在FPGA中因为电路驱动的复杂性,与单片机相同,咱们无法在电脑上完成“Hello World”的显现,而有必要依托相关硬件。因而咱们不得不在必定的基础上,才干解说关于LCD1602字符液晶的驱动,以及Hello World的显现。

  相同于前面MCU按键消颤动移植代码,此处也能够移植MCU LCD1602驱动代码。本例程不是Bingo原创,是依照网友“小时不识月”的代码,移植修正最终定型为Bingo版别(O(∩_∩)O哈哈~)。

  电路图此处不解说,太简略了。

  一、驱动阐明

  因为FPGA的高速并行操作,并非次序履行,在代码上与MCU有所不同。此处先解说驱动原理:

  (1)分频以得到500KHz固定的频率,初始化LCD1602。如下图所示,LCD_EN的频率应该控制在2M以内(不同的LCD1602参数会有所不同)。

  

wps_clip_image-31116

 

  (2)经过三段式状况机,来初始化以及给数据。

  (3)经过循环读取某一“数组”,循环给LCD1602数据,以接口方式便利改动。

  二、FPGA LCD1602 FSM

  1. 代码

  /*************************************************

  * Module Name : lcd1602_driver

  * Engineer : Crazy Bingo

  * Target Device : EP2C8Q208C8

  * Tool versions : Quartus II 11.0

  * Create Date : 2011-7-3

  * Revision : v1.0

  * Description :

  **************************************************/

  module lcd1602_driver

  (

  input clk,

  input rst_n,

  output lcd_en, // lcd enable

  output reg lcd_rs, // record,statement

  output lcd_rw,

  output reg [7:0] lcd_data

  );

  parameter [127:0] line_rom1 = "I am CrazyBingo!";

  parameter [127:0] line_rom2 = "Hello World*^_^*";

  //————————————–

  reg [15:0] cnt;

  always @ (posedge clk or negedge rst_n)

  begin

  if(!rst_n)

  cnt <= 0;

  else

  cnt <= cnt + 1’b1;

  end

  assign lcd_en = cnt[15]; //lcd enable,keep same time

  assign lcd_rw = 1’b0; //write only

  wire cmd_flag = (cnt == 16’h7FFF) ? 1’b1 : 1’b0; //when lcd_en is steady,write a cmd

  //—————————————

  // Gray code : 40 states

  parameter IDLE = 8’h00; // IDLE

  // lcd init

  parameter DISP_SET = 8’h01; // display mode

  parameter DISP_OFF = 8’h03; // off display

  parameter CLR_SCR = 8’h02; // clear the lcd

  parameter CURSOR_SET1 = 8’h06; // cursor set

  parameter CURSOR_SET2 = 8’h07; // on display, cursor set

  // display 1th line

  parameter ROW1_ADDR = 8’h05;

  parameter ROW1_0 = 8’h04;

  parameter ROW1_1 = 8’h0C;

  parameter ROW1_2 = 8’h0D;

  parameter ROW1_3 = 8’h0F;

  parameter ROW1_4 = 8’h0E;

  parameter ROW1_5 = 8’h0A;

  parameter ROW1_6 = 8’h0B;

  parameter ROW1_7 = 8’h09;

  parameter ROW1_8 = 8’h08;

  parameter ROW1_9 = 8’h18;

  parameter ROW1_A = 8’h19;

  parameter ROW1_B = 8’h1B;

  parameter ROW1_C = 8’h1A;

  parameter ROW1_D = 8’h1E;

  parameter ROW1_E = 8’h1F;

  parameter ROW1_F = 8’h1D;

  // display 2th line

  parameter ROW2_ADDR = 8’h1C;

  parameter ROW2_0 = 8’h14;

  parameter ROW2_1 = 8’h15;

  parameter ROW2_2 = 8’h17;

  parameter ROW2_3 = 8’h16;

  parameter ROW2_4 = 8’h12;

  parameter ROW2_5 = 8’h13;

  parameter ROW2_6 = 8’h11;

  parameter ROW2_7 = 8’h10;

  parameter ROW2_8 = 8’h30;

  parameter ROW2_9 = 8’h31;

  parameter ROW2_A = 8’h33;

  parameter ROW2_B = 8’h32;

  parameter ROW2_C = 8’h36;

  parameter ROW2_D = 8’h37;

  parameter ROW2_E = 8’h35;

  parameter ROW2_F = 8’h34;

  //—————————————

  reg [5:0] current_state, next_state;

  // FSM: always1

  always @ (posedge clk or negedge rst_n)

  begin

  if(!rst_n)

  current_state <= IDLE;

  else if(cmd_flag)

  current_state <= next_state;

  end

  //—————————————

  // FSM: always2

  always@*

  begin

  case(current_state)

  // lcd init

  IDLE : next_state = DISP_SET;

  DISP_SET : next_state = DISP_OFF;

  DISP_OFF : next_state = CLR_SCR;

  CLR_SCR : next_state = CURSOR_SET1;

  CURSOR_SET1 : next_state = CURSOR_SET2;

  CURSOR_SET2 : next_state = ROW1_ADDR;

  // display 1th line

  ROW1_ADDR : next_state = ROW1_0;

  ROW1_0 : next_state = ROW1_1;

  ROW1_1 : next_state = ROW1_2;

  ROW1_2 : next_state = ROW1_3;

  ROW1_3 : next_state = ROW1_4;

  ROW1_4 : next_state = ROW1_5;

  ROW1_5 : next_state = ROW1_6;

  ROW1_6 : next_state = ROW1_7;

  ROW1_7 : next_state = ROW1_8;

  ROW1_8 : next_state = ROW1_9;

  ROW1_9 : next_state = ROW1_A;

  ROW1_A : next_state = ROW1_B;

  ROW1_B : next_state = ROW1_C;

  ROW1_C : next_state = ROW1_D;

  ROW1_D : next_state = ROW1_E;

  ROW1_E : next_state = ROW1_F;

  ROW1_F : next_state = ROW2_ADDR;

  // display 2th line

  ROW2_ADDR : next_state = ROW2_0;

  ROW2_0 : next_state = ROW2_1;

  ROW2_1 : next_state = ROW2_2;

  ROW2_2 : next_state = ROW2_3;

  ROW2_3 : next_state = ROW2_4;

  ROW2_4 : next_state = ROW2_5;

  ROW2_5 : next_state = ROW2_6;

  ROW2_6 : next_state = ROW2_7;

  ROW2_7 : next_state = ROW2_8;

  ROW2_8 : next_state = ROW2_9;

  ROW2_9 : next_state = ROW2_A;

  ROW2_A : next_state = ROW2_B;

  ROW2_B : next_state = ROW2_C;

  ROW2_C : next_state = ROW2_D;

  ROW2_D : next_state = ROW2_E;

  ROW2_E : next_state = ROW2_F;

  ROW2_F : next_state = ROW1_ADDR;

  default : next_state = IDLE ;

  endcase

  end

  //—————————————

  // FSM: always3

  always @ (posedge clk or negedge rst_n)

  begin

  if(!rst_n)

  begin

  lcd_rs <= 0;

  lcd_data <= 8’hXX;

  end

  else if(cmd_flag)

  begin

  // write statement

  case(next_state)

  IDLE : lcd_rs <= 0; //statement

  //lcd init

  DISP_SET : lcd_rs <= 0; //statement

  DISP_OFF : lcd_rs <= 0; //statement

  CLR_SCR : lcd_rs <= 0; //statement

  CURSOR_SET1 : lcd_rs <= 0; //statement

  CURSOR_SET2 : lcd_rs <= 0; //statement

  // display 1th line

  ROW1_ADDR : lcd_rs <= 0; //statement

  ROW1_0 : lcd_rs <= 1; //record

  ROW1_1 : lcd_rs <= 1; //record

  ROW1_2 : lcd_rs <= 1; //record

  ROW1_3 : lcd_rs <= 1; //record

  ROW1_4 : lcd_rs <= 1; //record

  ROW1_5 : lcd_rs <= 1; //record

  ROW1_6 : lcd_rs <= 1; //record

  ROW1_7 : lcd_rs <= 1; //record

  ROW1_8 : lcd_rs <= 1; //record

  ROW1_9 : lcd_rs <= 1; //record

  ROW1_A : lcd_rs <= 1; //record

  ROW1_B : lcd_rs <= 1; //record

  ROW1_C : lcd_rs <= 1; //record

  ROW1_D : lcd_rs <= 1; //record

  ROW1_E : lcd_rs <= 1; //record

  ROW1_F : lcd_rs <= 1; //record

  // display 2th line

  ROW2_ADDR : lcd_rs <= 0; //statement

  ROW2_0 : lcd_rs <= 1; //record

  ROW2_1 : lcd_rs <= 1; //record

  ROW2_2 : lcd_rs <= 1; //record

  ROW2_3 : lcd_rs <= 1; //record

  ROW2_4 : lcd_rs <= 1; //record

  ROW2_5 : lcd_rs <= 1; //record

  ROW2_6 : lcd_rs <= 1; //record

  ROW2_7 : lcd_rs <= 1; //record

  ROW2_8 : lcd_rs <= 1; //record

  ROW2_9 : lcd_rs <= 1; //record

  ROW2_A : lcd_rs <= 1; //record

  ROW2_B : lcd_rs <= 1; //record

  ROW2_C : lcd_rs <= 1; //record

  ROW2_D : lcd_rs <= 1; //record

  ROW2_E : lcd_rs <= 1; //record

  ROW2_F : lcd_rs <= 1; //record

  endcase

  // write lcd_data

  case(next_state)

  IDLE : lcd_data <= 8’hxx;

  //lcd init

  DISP_SET : lcd_data <= 8’h38; //set 16X2,5X7 ,8 bits record

  DISP_OFF : lcd_data <= 8’h08; //off display

  CLR_SCR : lcd_data <= 8’h01; //clear lcd

  CURSOR_SET1 : lcd_data <= 8’h06; //cursor set

  CURSOR_SET2 : lcd_data <= 8’h0C; //on display

  // display 1th line

  ROW1_ADDR : lcd_data <= 8’h80;

  ROW1_0 : lcd_data <= line_rom1[127:120];

  ROW1_1 : lcd_data <= line_rom1[119:112];

  ROW1_2 : lcd_data <= line_rom1[111:104];

  ROW1_3 : lcd_data <= line_rom1[103: 96];

  ROW1_4 : lcd_data <= line_rom1[ 95: 88];

  ROW1_5 : lcd_data <= line_rom1[ 87: 80];

  ROW1_6 : lcd_data <= line_rom1[ 79: 72];

  ROW1_7 : lcd_data <= line_rom1[ 71: 64];

  ROW1_8 : lcd_data <= line_rom1[ 63: 56];

  ROW1_9 : lcd_data <= line_rom1[ 55: 48];

  ROW1_A : lcd_data <= line_rom1[ 47: 40];

  ROW1_B : lcd_data <= line_rom1[ 39: 32];

  ROW1_C : lcd_data <= line_rom1[ 31: 24];

  ROW1_D : lcd_data <= line_rom1[ 23: 16];

  ROW1_E : lcd_data <= line_rom1[ 15: 8];

  ROW1_F : lcd_data <= line_rom1[ 7: 0];

  // display 2th line

  ROW2_ADDR : lcd_data <= 8’hC0;

  ROW2_0 : lcd_data <= line_rom2[127:120];

  ROW2_1 : lcd_data <= line_rom2[119:112];

  ROW2_2 : lcd_data <= line_rom2[111:104];

  ROW2_3 : lcd_data <= line_rom2[103: 96];

  ROW2_4 : lcd_data <= line_rom2[ 95: 88];

  ROW2_5 : lcd_data <= line_rom2[ 87: 80];

  ROW2_6 : lcd_data <= line_rom2[ 79: 72];

  ROW2_7 : lcd_data <= line_rom2[ 71: 64];

  ROW2_8 : lcd_data <= line_rom2[ 63: 56];

  ROW2_9 : lcd_data <= line_rom2[ 55: 48];

  ROW2_A : lcd_data <= line_rom2[ 47: 40];

  ROW2_B : lcd_data <= line_rom2[ 39: 32];

  ROW2_C : lcd_data <= line_rom2[ 31: 24];

  ROW2_D : lcd_data <= line_rom2[ 23: 16];

  ROW2_E : lcd_data <= line_rom2[ 15: 8];

  ROW2_F : lcd_data <= line_rom2[ 7: 0];

  endcase

  end

  end

  endmodule

  2. 状况机

  (1)以下是State machine如下所示:

  

wps_clip_image-31119

 

  (2)模块可分为一下几个状况

  

image

 

  3. “Hello World”什物显现

  parameter [127:0] line_rom1 = "I am CrazyBingo!";

  parameter [127:0] line_rom2 = "Hello World*^_^*";

  

wps_clip_image-31174

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