基于STEP FPGA的SPI RGB液晶屏显示驱动
本节将和大家一起使用FPGA驱动底板上的1.8寸RGB液晶屏实现图片显示功能。
硬件说明
我们的STEP-BaseBoard底板上集成了1.8寸彩色液晶屏TFT_LCD模块，大家可以驱动LCD显示文字、图片或动态的波形。
首先了解一下液晶屏模块，相关资料下载：https://pan.baidu.com/s/1bp6AYsR
框图如下：
原理图如下：
原理图中的器件U1为液晶屏，液晶屏为1.8寸，128RGB160像素，串行总线（SPI），液晶屏集成了ST7735S的驱动器，处理器与ST7735S通信完成液晶屏的显示控制
ST7735S为132RGB x 162像素点 262K 控制器/驱动器，芯片可以直接跟外部处理器连接，支持串行SPI通信和8/9/16/18位并行通信（本液晶屏集成ST7735S时没有留并行接口，所以只能使用串行通信），详细参数请参考数据手册：st7735s_datasheet.pdf
Verilog代码
// -------------------------------------------------------------------- // >>>>>>>>>>>>>>>>>>>>>>>>> COPYRIGHT NOTICE <<<<<<<<<<<<<<<<<<<<<<<<< // -------------------------------------------------------------------- // Module: LCD_RGB // // Author: Step // // Description: Drive TFT_RGB_LCD_1.8 to display // // Web: www.stepfpga.com // // -------------------------------------------------------------------- // Code Revision History : // -------------------------------------------------------------------- // Version: |Mod. Date: |Changes Made: // V1.1 |2016/10/30 |Initial ver // -------------------------------------------------------------------- module LCD_RGB # ( parameter LCD_W = 8'd132, //液晶屏像素宽度 parameter LCD_H = 8'd162 //液晶屏像素高度 ) ( input clk_in, //12MHz系统时钟 input rst_n_in, //系统复位，低有效 output reg ram_lcd_clk_en, //RAM时钟使能 output reg [7:0] ram_lcd_addr, //RAM地址信号 input [131:0] ram_lcd_data, //RAM数据信号 output reg lcd_rst_n_out, //LCD液晶屏复位 output reg lcd_bl_out, //LCD背光控制 output reg lcd_dc_out, //LCD数据指令控制 output reg lcd_clk_out, //LCD时钟信号 output reg lcd_data_out //LCD数据信号 ); localparam INIT_DEPTH = 16'd73; //LCD初始化的命令及数据的数量 localparam RED = 16'hf800; //红色 localparam GREEN = 16'h07e0; //绿色 localparam BLUE = 16'h001f; //蓝色 localparam BLACK = 16'h0000; //黑色 localparam WHITE = 16'hffff; //白色 localparam YELLOW = 16'hffe0; //黄色 localparam IDLE = 3'd0; localparam MAIN = 3'd1; localparam INIT = 3'd2; localparam SCAN = 3'd3; localparam WRITE = 3'd4; localparam DELAY = 3'd5; localparam LOW = 1'b0; localparam HIGH = 1'b1; //assign lcd_bl_out = HIGH; // backlight active high level wire [15:0] color_t = YELLOW; //顶层色为黄色 wire [15:0] color_b = BLACK; //背景色为黑色 reg [7:0] x_cnt; reg [7:0] y_cnt; reg [131:0] ram_data_r; reg [8:0] data_reg; // reg [8:0] reg_setxy [10:0]; reg [8:0] reg_init [72:0]; reg [2:0] cnt_main; reg [2:0] cnt_init; reg [2:0] cnt_scan; reg [5:0] cnt_write; reg [15:0] cnt_delay; reg [15:0] num_delay; reg [15:0] cnt; reg high_word; reg [2:0] state = IDLE; reg [2:0] state_back = IDLE; always@(posedge clk_in or negedge rst_n_in) begin if(!rst_n_in) begin x_cnt <= 8'd0; y_cnt <= 8'd0; ram_lcd_clk_en <= 1'b0; ram_lcd_addr <= 8'd0; cnt_main <= 3'd0; cnt_init <= 3'd0; cnt_scan <= 3'd0; cnt_write <= 6'd0; cnt_delay <= 16'd0; num_delay <= 16'd50; cnt <= 16'd0; high_word <= 1'b1; lcd_bl_out <= LOW; state <= IDLE; state_back <= IDLE; end else begin case(state) IDLE:begin x_cnt <= 8'd0; y_cnt <= 8'd0; ram_lcd_clk_en <= 1'b0; ram_lcd_addr <= 8'd0; cnt_main <= 3'd0; cnt_init <= 3'd0; cnt_scan <= 3'd0; cnt_write <= 6'd0; cnt_delay <= 16'd0; num_delay <= 16'd50; cnt <= 16'd0; high_word <= 1'b1; state <= MAIN; state_back <= MAIN; end MAIN:begin case(cnt_main) //MAIN状态 3'd0: begin state <= INIT; cnt_main <= cnt_main + 1'b1; end 3'd1: begin state <= SCAN; cnt_main <= cnt_main + 1'b1; end 3'd2: begin cnt_main <= 1'b1; end default: state <= IDLE; endcase end INIT:begin //初始化状态 case(cnt_init) 3'd0: begin lcd_rst_n_out <= 1'b0; cnt_init <= cnt_init + 1'b1; end //复位有效 3'd1: begin num_delay <= 16'd3000; state <= DELAY; state_back <= INIT; cnt_init <= cnt_init + 1'b1; end //延时 3'd2: begin lcd_rst_n_out <= 1'b1; cnt_init <= cnt_init + 1'b1; end //复位恢复 3'd3: begin num_delay <= 16'd3000; state <= DELAY; state_back <= INIT; cnt_init <= cnt_init + 1'b1; end //延时 3'd4: begin if(cnt>=INIT_DEPTH) begin //当73条指令及数据发出后，配置完成 cnt <= 16'd0; cnt_init <= cnt_init + 1'b1; end else begin data_reg <= reg_init[cnt]; if(cnt==16'd0) num_delay <= 16'd50000; //第一条指令需要较长延时 else num_delay <= 16'd50; cnt <= cnt + 16'd1; state <= WRITE; state_back <= INIT; end end 3'd5: begin cnt_init <= 1'b0; state <= MAIN; end //初始化完成，返回MAIN状态 default: state <= IDLE; endcase end SCAN:begin //刷屏状态，从RAM中读取数据刷屏 case(cnt_scan) 3'd0: begin //确定刷屏的区域坐标，这里为全屏 if(cnt >= 11) begin // cnt <= 16'd0; cnt_scan <= cnt_scan + 1'b1; end else begin data_reg <= reg_setxy[cnt]; cnt <= cnt + 16'd1; num_delay <= 16'd50; state <= WRITE; state_back <= SCAN; end end 3'd1: begin ram_lcd_clk_en <= HIGH; ram_lcd_addr <= y_cnt; cnt_scan <= cnt_scan + 1'b1; end //RAM时钟使能 3'd2: begin cnt_scan <= cnt_scan + 1'b1; end //延时一个时钟 3'd3: begin ram_lcd_clk_en <= LOW; ram_data_r <= ram_lcd_data; cnt_scan <= cnt_scan + 1'b1; end //读取RAM数据，同时关闭RAM时钟使能 3'd4: begin //每个像素点需要16bit的数据，SPI每次传8bit，两次分别传送高8位和低8位 if(x_cnt>=LCD_W) begin //当一个数据(一行屏幕)写完后， x_cnt <= 8'd0; if(y_cnt>=LCD_H) begin y_cnt <= 8'd0; cnt_scan <= cnt_scan + 1'b1; end //如果是最后一行就跳出循环 else begin y_cnt <= y_cnt + 1'b1; cnt_scan <= 3'd1; end //否则跳转至RAM时钟使能，循环刷屏 end else begin if(high_word) data_reg <= {1'b1,(ram_data_r[x_cnt]? color_t[15:8]:color_b[15:8])}; //根据相应bit的状态判定显示顶层色或背景色,根据high_word的状态判定写高8位或低8位 else begin data_reg <= {1'b1,(ram_data_r[x_cnt]? color_t[7:0]:color_b[7:0])}; x_cnt <= x_cnt + 1'b1; end //根据相应bit的状态判定显示顶层色或背景色,根据high_word的状态判定写高8位或低8位，同时指向下一个bit high_word <= ~high_word; //high_word的状态翻转 num_delay <= 16'd50; //设定延时时间 state <= WRITE; //跳转至WRITE状态 state_back <= SCAN; //执行完WRITE及DELAY操作后返回SCAN状态 end end 3'd5: begin cnt_scan <= 1'b0; lcd_bl_out <= HIGH; state <= MAIN; end default: state <= IDLE; endcase end WRITE:begin //WRITE状态，将数据按照SPI时序发送给屏幕 if(cnt_write >= 6'd17) cnt_write <= 1'b0; else cnt_write <= cnt_write + 1'b1; case(cnt_write) 6'd0: begin lcd_dc_out <= data_reg[8]; end //9位数据最高位为命令数据控制位 6'd1: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[7]; end //先发高位数据 6'd2: begin lcd_clk_out <= HIGH; end 6'd3: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[6]; end 6'd4: begin lcd_clk_out <= HIGH; end 6'd5: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[5]; end 6'd6: begin lcd_clk_out <= HIGH; end 6'd7: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[4]; end 6'd8: begin lcd_clk_out <= HIGH; end 6'd9: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[3]; end 6'd10: begin lcd_clk_out <= HIGH; end 6'd11: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[2]; end 6'd12: begin lcd_clk_out <= HIGH; end 6'd13: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[1]; end 6'd14: begin lcd_clk_out <= HIGH; end 6'd15: begin lcd_clk_out <= LOW; lcd_data_out <= data_reg[0]; end //后发低位数据 6'd16: begin lcd_clk_out <= HIGH; end 6'd17: begin lcd_clk_out <= LOW; state <= DELAY; end // default: state <= IDLE; endcase end DELAY:begin //延时状态 if(cnt_delay >= num_delay) begin cnt_delay <= 16'd0; state <= state_back; end else cnt_delay <= cnt_delay + 1'b1; end default:state <= IDLE; endcase end end // data for setxy initial //设定显示区域指令及数据 begin reg_setxy[0] = {1'b0,8'h2a}; reg_setxy[1] = {1'b1,8'h00}; reg_setxy[2] = {1'b1,8'h00}; reg_setxy[3] = {1'b1,8'h00}; reg_setxy[4] = {1'b1,LCD_W-1}; reg_setxy[5] = {1'b0,8'h2b}; reg_setxy[6] = {1'b1,8'h00}; reg_setxy[7] = {1'b1,8'h00}; reg_setxy[8] = {1'b1,8'h00}; reg_setxy[9] = {1'b1,LCD_H-1}; reg_setxy[10] = {1'b0,8'h2c}; end // data for init initial //LCD初始化的命令及数据 begin reg_init[0] = {1'b0,8'h11}; reg_init[1] = {1'b0,8'hb1}; reg_init[2] = {1'b1,8'h05}; reg_init[3] = {1'b1,8'h3c}; reg_init[4] = {1'b1,8'h3c}; reg_init[5] = {1'b0,8'hb2}; reg_init[6] = {1'b1,8'h05}; reg_init[7] = {1'b1,8'h3c}; reg_init[8] = {1'b1,8'h3c}; reg_init[9] = {1'b0,8'hb3}; reg_init[10] = {1'b1,8'h05}; reg_init[11] = {1'b1,8'h3c}; reg_init[12] = {1'b1,8'h3c}; reg_init[13] = {1'b1,8'h05}; reg_init[14] = {1'b1,8'h3c}; reg_init[15] = {1'b1,8'h3c}; reg_init[16] = {1'b0,8'hb4}; reg_init[17] = {1'b1,8'h03}; reg_init[18] = {1'b0,8'hc0}; reg_init[19] = {1'b1,8'h28}; reg_init[20] = {1'b1,8'h08}; reg_init[21] = {1'b1,8'h04}; reg_init[22] = {1'b0,8'hc1}; reg_init[23] = {1'b1,8'hc0}; reg_init[24] = {1'b0,8'hc2}; reg_init[25] = {1'b1,8'h0d}; reg_init[26] = {1'b1,8'h00}; reg_init[27] = {1'b0,8'hc3}; reg_init[28] = {1'b1,8'h8d}; reg_init[29] = {1'b1,8'h2a}; reg_init[30] = {1'b0,8'hc4}; reg_init[31] = {1'b1,8'h8d}; reg_init[32] = {1'b1,8'hee}; reg_init[32] = {1'b0,8'hc5}; reg_init[33] = {1'b1,8'h1a}; reg_init[34] = {1'b0,8'h36}; reg_init[35] = {1'b1,8'hc0}; reg_init[36] = {1'b0,8'he0}; reg_init[37] = {1'b1,8'h04}; reg_init[38] = {1'b1,8'h22}; reg_init[39] = {1'b1,8'h07}; reg_init[40] = {1'b1,8'h0a}; reg_init[41] = {1'b1,8'h2e}; reg_init[42] = {1'b1,8'h30}; reg_init[43] = {1'b1,8'h25}; reg_init[44] = {1'b1,8'h2a}; reg_init[45] = {1'b1,8'h28}; reg_init[46] = {1'b1,8'h26}; reg_init[47] = {1'b1,8'h2e}; reg_init[48] = {1'b1,8'h3a}; reg_init[49] = {1'b1,8'h00}; reg_init[50] = {1'b1,8'h01}; reg_init[51] = {1'b1,8'h03}; reg_init[52] = {1'b1,8'h13}; reg_init[53] = {1'b0,8'he1}; reg_init[54] = {1'b1,8'h04}; reg_init[55] = {1'b1,8'h16}; reg_init[56] = {1'b1,8'h06}; reg_init[57] = {1'b1,8'h0d}; reg_init[58] = {1'b1,8'h2d}; reg_init[59] = {1'b1,8'h26}; reg_init[60] = {1'b1,8'h23}; reg_init[61] = {1'b1,8'h27}; reg_init[62] = {1'b1,8'h27}; reg_init[63] = {1'b1,8'h25}; reg_init[64] = {1'b1,8'h2d}; reg_init[65] = {1'b1,8'h3b}; reg_init[66] = {1'b1,8'h00}; reg_init[67] = {1'b1,8'h01}; reg_init[68] = {1'b1,8'h04}; reg_init[69] = {1'b1,8'h13}; reg_init[70] = {1'b0,8'h3a}; reg_init[71] = {1'b1,8'h05}; reg_init[72] = {1'b0,8'h29}; end endmodule
小结
本节主要为大家讲解了1.8寸RGB液晶屏图片显示的框架，需要大家掌握的同时自己创建工程，通过整个设计流程，生成FPGA配置文件加载测试。
如果你对Diamond软件的使用不了解，请参考这里：Diamond的使用。
相关资料
使用STEP-MXO2第二代的1.8寸RGB液晶屏显示驱动程序: 后续会有下载连接 待更新
使用STEP-MAX10的1.8寸RGB液晶屏显示驱动程序: 后续会有下载连接 待更新