Chapter 5 are you okay-LCD 12th Hello World

As mentioned above, "Hello World" will be the first language to learn in C, C ++ and other languages.CodeHowever, in FPGA, because of the complexity of circuit driving, similar to single-chip microcomputer, we cannot achieve "Hello World" display on the computer, but must rely on relevant hardware. Therefore, we have to explain the driver of the lcd1602 character liquid crystal and the hello World display on a certain basis.

Similar to the preceding MCU key jitter transplant code, the MCU lcd1602 driver code can also be transplanted here. This routine is not original in Bingo. It is based on the Code of the netizen "The hour does not recognize the month". It is transplanted and modified to the bingo version (O (Taobao _ blank) O Haha ~).

The circuit diagram is not explained here. It is too simple.

1. Driver description

Because FPGA's high-speed parallel operations are not sequential execution, the code is different from MCU. Here we will first explain the driver principle:

(1) frequency division to get a fixed frequency of kHz and initialize lcd1602. As shown in, the frequency of LCD _en should be controlled within 2 MB (different lcd1602 parameters may vary ).

(2) initialize and give data through a three-stage state machine.

(3) read an "array" cyclically and feed the lcd1602 data cyclically, facilitating changes in the form of interfaces.

Ii. FPGA lcd1602 fsm1. code

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

* 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 [expiration :0] line_rom1 = "I am crazybingo! ";

Parameter [expiration :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 1__flag = (CNT = 16 '0000fff )? 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 (pai_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 = roww.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 (pai_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 [:120];

Row1_1: LCD _data <= line_rom1 [119:112];

Row1_2: LCD _data <= line_rom1 [11:104];

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 [:120];

Row2_1: LCD _data <= line_rom2 [119:112];

Row2_2: LCD _data <= line_rom2 [11:104];

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. State Machine

(1) The following is the state machine:

(2) The module can be divided into several statuses.

3. "Hello World" physical display

Parameter [expiration :0] line_rom1 = "I am crazybingo! ";

Parameter [expiration :0] line_rom2 = "Hello world * ^_^ *";