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后一修订版 		前一修订版
fpga16_instrument [2021/02/24 17:16]
gongyusu 		fpga16_instrument [2021/03/08 17:38] (当前版本)
gongyusu [OLED显示及按键控制]
行 24: 行 24:
 因此在实际的使用中，我们一般避免将占空比用到0%或100%，比如可以从10% - 90%之间变化，经过低通滤波器平滑输出后的直流在3.3*10% ~ 3.3 * 90% - 0.33V - 2.97V  因此在实际的使用中，我们一般避免将占空比用到0%或100%，比如可以从10% - 90%之间变化，经过低通滤波器平滑输出后的直流在3.3*10% ~ 3.3 * 90% - 0.33V - 2.97V 
  
 +在生成PWM的波形的时候要充分理解PWM的时序关系，见下图：
 +{{ :​pwm_timing.png |}}<WRAP centeralign>​ PWM的时序关系 </​WRAP>​
 +
 +t为生成PWM信号的主时钟，通过对这个高频时钟计数，得到一个周期T内电平进行0、1反转的脉宽不同的信号。一个T内有多少个t，也就决定了PWM的分辨率，转换到模拟信号的时候也就对应于DAC的位数。根据最高频率/​分辨率，也就可以推算出T的最小值。
 +
 +比如采用12MHz（t=83ns）的时钟作为PWM的主时钟，如果要生成8位精度的DAC，对应的一个PWM周期T ～ 12MHz/256 = 21μs，最高的频率为47KHz
 +如果通过FPGA内部PLL产生高倍频的时钟，比如12M * 16 ～ 192MHz，生成8位精度的DAC，其最高频率可以达到47KHz * 16
 +同样192MHz的主时钟来产生12位精度的DAC，则能够生成PWM信号的频率为47KHz
 +
 +### OLED显示及按键控制
 +本平台采用了128*64分辨率的OLED显示屏，并有4个按键进行参数的设置或菜单的控制，这些按键的功能可以根据自己的需要进行定制。
 +
 +下面的代码完成了OLED显示屏的驱动，并在屏幕上显示一些与口袋仪器相关的参数，4个按键的扫描控制功能也一并包含在内。
 +<code verilog>
 +// --------------------------------------------------------------------
 +// >>>>>>>>>>>>>>>>>>>>>>>>>​ COPYRIGHT NOTICE <<<<<<<<<<<<<<<<<<<<<<<<<​
 +// --------------------------------------------------------------------
 +// Module: OLED12832
 +// 
 +// Author: Step
 +// 
 +// Description:​ OLED12832_Driver
 +// 
 +// Web: www.stepfpga.com
 +// 
 +// --------------------------------------------------------------------
 +// Code Revision History :
 +// --------------------------------------------------------------------
 +// Version: |Mod. Date:   ​|Changes Made:
 +// V1.0     ​|2015/​11/​11 ​  ​|Initial ver
 +// --------------------------------------------------------------------
 +module OLED12832
 +(
 + input clk, //
 + input rst_n, //
 + input [3:0]  sw,// 4 push buttons as control input
 + input [7:0]  freq_100, ​
 + input [7:0]  freq_10, ​
 + input [7:0]  freq_1,
 + input [7:0]  dc1_10,
 + input [7:0]  dc1_1,
 + input [7:0]  dc1_01,
 + input [7:0]  dc2_10,
 + input [7:0]  dc2_1,
 + input [7:0]  dc2_01,
 + 
 + output reg oled_csn,​ //​
 + output reg oled_rst,​ //​
 + output reg oled_dcn,​ //​
 + output reg oled_clk,​ //​
 + output reg oled_dat
 +);
 +
 + localparam INIT_DEPTH = 16'​d28;​ //
 + localparam IDLE = 6'h1, MAIN = 6'h2, INIT = 6'h4, SCAN = 6'h8, WRITE = 6'h10, DELAY = 6'h20;
 + localparam HIGH = 1'b1, LOW = 1'b0;
 + localparam DATA = 1'b1, CMD = 1'b0;
 +
 + reg [7:0] cmd [27:0];
 + reg [39:0] mem [122:0];
 + reg [7:0] y_p, x_ph, x_pl;
 + reg [(8*21-1):​0] char;
 + reg [7:0] num, char_reg;​ //​
 + reg [4:0] cnt_main, cnt_init, cnt_scan, cnt_write;
 + reg [15:0] num_delay, cnt_delay, cnt;
 + reg [5:0] state, state_back;
 +
 + always@(posedge clk or negedge rst_n) begin
 + if(!rst_n) begin
 + cnt_main <= 1'b0; cnt_init <= 1'b0; cnt_scan <= 1'b0; cnt_write <= 1'b0;
 + y_p <= 1'b0; x_ph <= 1'b0; x_pl <= 1'b0;
 + num <= 1'b0; char <= 1'b0; char_reg <= 1'b0;
 + num_delay <= 16'd5; cnt_delay <= 1'b0; cnt <= 1'b0;
 + oled_csn <= HIGH; oled_rst <= HIGH; oled_dcn <= CMD; oled_clk <= HIGH; oled_dat <= LOW;
 + state <= IDLE; state_back <= IDLE;
 + end else begin
 + case(state)
 + IDLE:​begin
 + cnt_main <= 1'b0; cnt_init <= 1'b0; cnt_scan <= 1'b0; cnt_write <= 1'b0;
 + y_p <= 1'b0; x_ph <= 1'b0; x_pl <= 1'b0;
 + num <= 1'b0; char <= 1'b0; char_reg <= 1'b0;
 + num_delay <= 16'd5; cnt_delay <= 1'b0; cnt <= 1'b0;
 + oled_csn <= HIGH; oled_rst <= HIGH; oled_dcn <= CMD; oled_clk <= HIGH; oled_dat <= LOW;
 + state <= MAIN; state_back <= MAIN;
 + end
 + MAIN:​begin
 + if(cnt_main >= 5'd16) cnt_main <= 5'd9;
 + else cnt_main <= cnt_main + 1'b1;
 + case(cnt_main) //​MAIN状态
 + 5'​d0:​ begin state <= INIT; end
 + 5'​d1:​ begin y_p <= 8'hb0; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= "​----------------";​state <= SCAN; end
 + 5'​d2:​ begin y_p <= 8'hb1; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " FPGA Training ​ ";​state <= SCAN; end
 + 5'​d3:​ begin y_p <= 8'hb2; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " www.eetree.cn ​ ";​state <= SCAN; end
 + 5'​d4:​ begin y_p <= 8'hb3; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= "​----------------";​state <= SCAN; end
 + 5'​d5:​ begin y_p <= 8'hb4; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " ​                ";​state <= SCAN; end
 + 5'​d6:​ begin y_p <= 8'hb5; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " ​                ";​state <= SCAN; end
 + 5'​d7:​ begin y_p <= 8'hb6; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " ​                ";​state <= SCAN; end
 +                                                        5'​d8:​ begin y_p <= 8'hb7; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd16; char <= " ​               ";​state <= SCAN; end
 + 5'​d9:​ begin y_p <= 8'hb4; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd13; char <= {"​I-->​W,​DC-1KHz"​} ;state <= SCAN; end
 + 5'​d10:​ begin y_p <= 8'hb5; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd10; char <= {"DC1: +3.0V"​} ​  ;​state <= SCAN; end
 + 5'​d11:​ begin y_p <= 8'hb6; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd10; char <= {"DC2: -3.0V"​} ​  ;​state <= SCAN; end
 +                                                        5'​d12:​ begin y_p <= 8'hb7; x_ph <= 8'h10; x_pl <= 8'h00; num <= 5'd12; char <= {"Have Fun! :)" };state <= SCAN; end
 + 5'​d13:​ begin y_p <= 8'hb4; x_ph <= 8'h17; x_pl <= 8'h08; num <= 5'd 1; char <= sw; state <= SCAN; end
 + 5'​d14:​ begin y_p <= 8'hb5; x_ph <= 8'h17; x_pl <= 8'h08; num <= 5'd 1; char <= sw; state <= SCAN; end
 + 5'​d15:​ begin y_p <= 8'hb6; x_ph <= 8'h17; x_pl <= 8'h08; num <= 5'd 1; char <= sw; state <= SCAN; end
 + 5'​d16:​ begin y_p <= 8'hb7; x_ph <= 8'h17; x_pl <= 8'h08; num <= 5'd 1; char <= sw; state <= SCAN; end
 +
 + default:​ state <= IDLE;
 + endcase
 + end
 + INIT:​begin //​
 + case(cnt_init)
 + 5'​d0:​ begin oled_rst <= LOW; cnt_init <= cnt_init + 1'b1; end //
 + 5'​d1:​ begin num_delay <= 16'​d25000;​ state <= DELAY; state_back <= INIT; cnt_init <= cnt_init + 1'b1; end //
 + 5'​d2:​ begin oled_rst <= HIGH; cnt_init <= cnt_init + 1'b1; end //
 + 5'​d3:​ begin num_delay <= 16'​d25000;​ state <= DELAY; state_back <= INIT; cnt_init <= cnt_init + 1'b1; end //
 + 5'​d4:​ begin ​
 + if(cnt>​=INIT_DEPTH) begin //
 + cnt <= 1'b0;
 + cnt_init <= cnt_init + 1'b1;
 + end else begin
 + cnt <= cnt + 1'b1; num_delay <= 16'd5;
 + oled_dcn <= CMD; char_reg <= cmd[cnt]; state <= WRITE; state_back <= INIT;
 + end
 + end
 + 5'​d5:​ begin cnt_init <= 1'b0; state <= MAIN; end //
 + default:​ state <= IDLE;
 + endcase
 + end
 + SCAN:​begin //​
 + if(cnt_scan == 5'd11) begin
 + if(num) cnt_scan <= 5'd3;
 + else cnt_scan <= cnt_scan + 1'b1;
 + end else if(cnt_scan == 5'd12) cnt_scan <= 1'b0;
 + else cnt_scan <= cnt_scan + 1'b1;
 + case(cnt_scan)
 + 5'​d 0: begin oled_dcn <= CMD; char_reg <= y_p; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 1: begin oled_dcn <= CMD; char_reg <= x_pl; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 2: begin oled_dcn <= CMD; char_reg <= x_ph; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 3: begin num <= num - 1'​b1;​end
 + 5'​d 4: begin oled_dcn <= DATA; char_reg <= 8'h00; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 5: begin oled_dcn <= DATA; char_reg <= 8'h00; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 6: begin oled_dcn <= DATA; char_reg <= 8'h00; state <= WRITE; state_back <= SCAN; end //
 + 5'​d 7: begin oled_dcn <= DATA; char_reg <= mem[char[(num*8)+:​8]][39:​32];​ state <= WRITE; state_back <= SCAN; end
 + 5'​d 8: begin oled_dcn <= DATA; char_reg <= mem[char[(num*8)+:​8]][31:​24];​ state <= WRITE; state_back <= SCAN; end
 + 5'​d 9: begin oled_dcn <= DATA; char_reg <= mem[char[(num*8)+:​8]][23:​16];​ state <= WRITE; state_back <= SCAN; end
 + 5'​d10:​ begin oled_dcn <= DATA; char_reg <= mem[char[(num*8)+:​8]][15:​ 8]; state <= WRITE; state_back <= SCAN; end
 + 5'​d11:​ begin oled_dcn <= DATA; char_reg <= mem[char[(num*8)+:​8]][ 7: 0]; state <= WRITE; state_back <= SCAN; end
 + 5'​d12:​ begin state <= MAIN; end
 + default:​ state <= IDLE;
 + endcase
 + end
 + WRITE:​begin //​
 + if(cnt_write >= 5'd17) cnt_write <= 1'b0;
 + else cnt_write <= cnt_write + 1'b1;
 + case(cnt_write)
 + 5'​d 0: begin oled_csn <= LOW; end //
 + 5'​d 1: begin oled_clk <= LOW; oled_dat <= char_reg[7];​ end //
 + 5'​d 2: begin oled_clk <= HIGH; end
 + 5'​d 3: begin oled_clk <= LOW; oled_dat <= char_reg[6];​ end
 + 5'​d 4: begin oled_clk <= HIGH; end
 + 5'​d 5: begin oled_clk <= LOW; oled_dat <= char_reg[5];​ end
 + 5'​d 6: begin oled_clk <= HIGH; end
 + 5'​d 7: begin oled_clk <= LOW; oled_dat <= char_reg[4];​ end
 + 5'​d 8: begin oled_clk <= HIGH; end
 + 5'​d 9: begin oled_clk <= LOW; oled_dat <= char_reg[3];​ end
 + 5'​d10:​ begin oled_clk <= HIGH; end
 + 5'​d11:​ begin oled_clk <= LOW; oled_dat <= char_reg[2];​ end
 + 5'​d12:​ begin oled_clk <= HIGH; end
 + 5'​d13:​ begin oled_clk <= LOW; oled_dat <= char_reg[1];​ end
 + 5'​d14:​ begin oled_clk <= HIGH; end
 + 5'​d15:​ begin oled_clk <= LOW; oled_dat <= char_reg[0];​ end //
 + 5'​d16:​ begin oled_clk <= HIGH; end
 + 5'​d17:​ begin oled_csn <= HIGH; state <= DELAY; end //
 + default:​ state <= IDLE;
 + endcase
 + end
 + DELAY:​begin //​
 + 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
 +
 + //
 + always@(negedge rst_n)
 +
 + begin
 + cmd[ 0] = {8'​hae}; ​
 + cmd[ 1] = {8'​h00}; ​
 + cmd[ 2] = {8'​h10}; ​
 + cmd[ 3] = {8'​h40}; ​
 + cmd[ 4] = {8'​h81}; ​
 + cmd[ 5] = {8'​hcf}; ​
 + cmd[ 6] = {8'​ha1}; ​
 + cmd[ 7] = {8'​hc8}; ​
 + cmd[ 8] = {8'​ha6}; ​
 + cmd[ 9] = {8'​ha8}; ​
 + cmd[10] = {8'​h3f}; ​
 + cmd[11] = {8'​hd3};​
 + cmd[12] = {8'​h00};​
 + cmd[13] = {8'​hd5};​
 + cmd[14] = {8'​h80};​
 + cmd[15] = {8'​hd9};​
 + cmd[16] = {8'​hf1};​
 + cmd[17] = {8'​hda};​
 + cmd[18] = {8'​h12};​
 + cmd[19] = {8'​hdb};​
 + cmd[20] = {8'​h40};​
 + cmd[21] = {8'​h20};​
 + cmd[22] = {8'​h02};​
 +            cmd[23] = {8'​h8d};​
 + cmd[24] = {8'​h14};​
 +            cmd[25] = {8'​ha4};​
 +            cmd[26] = {8'​ha6};​
 + cmd[27] = {8'​haf};​
 + end
 +
 + always@(negedge rst_n)
 + //initial
 + begin
 + mem[ ​ 0] = {8'​h3E,​ 8'h51, 8'h49, 8'h45, 8'​h3E}; ​  // 48  0
 + mem[ ​ 1] = {8'​h00,​ 8'h42, 8'h7F, 8'h40, 8'​h00}; ​  // 49  1
 + mem[ ​ 2] = {8'​h42,​ 8'h61, 8'h51, 8'h49, 8'​h46}; ​  // 50  2
 + mem[ ​ 3] = {8'​h21,​ 8'h41, 8'h45, 8'h4B, 8'​h31}; ​  // 51  3
 + mem[ ​ 4] = {8'​h18,​ 8'h14, 8'h12, 8'h7F, 8'​h10}; ​  // 52  4
 + mem[ ​ 5] = {8'​h27,​ 8'h45, 8'h45, 8'h45, 8'​h39}; ​  // 53  5
 + mem[ ​ 6] = {8'​h3C,​ 8'h4A, 8'h49, 8'h49, 8'​h30}; ​  // 54  6
 + mem[ ​ 7] = {8'​h01,​ 8'h71, 8'h09, 8'h05, 8'​h03}; ​  // 55  7
 + mem[ ​ 8] = {8'​h36,​ 8'h49, 8'h49, 8'h49, 8'​h36}; ​  // 56  8
 + mem[ ​ 9] = {8'​h06,​ 8'h49, 8'h49, 8'h29, 8'​h1E}; ​  // 57  9
 + mem[ 10] = {8'​h7C,​ 8'h12, 8'h11, 8'h12, 8'​h7C}; ​  // 65  A
 + mem[ 11] = {8'​h7F,​ 8'h49, 8'h49, 8'h49, 8'​h36}; ​  // 66  B
 + mem[ 12] = {8'​h3E,​ 8'h41, 8'h41, 8'h41, 8'​h22}; ​  // 67  C
 + mem[ 13] = {8'​h7F,​ 8'h41, 8'h41, 8'h22, 8'​h1C}; ​  // 68  D
 + mem[ 14] = {8'​h7F,​ 8'h49, 8'h49, 8'h49, 8'​h41}; ​  // 69  E
 + mem[ 15] = {8'​h7F,​ 8'h09, 8'h09, 8'h09, 8'​h01}; ​  // 70  F
 +
 + mem[ 32] = {8'​h00,​ 8'h00, 8'h00, 8'h00, 8'​h00}; ​  // 32  sp 
 + mem[ 33] = {8'​h00,​ 8'h00, 8'h2f, 8'h00, 8'​h00}; ​  // 33  !  ​
 + mem[ 34] = {8'​h00,​ 8'h07, 8'h00, 8'h07, 8'​h00}; ​  // 34  ​
 + mem[ 35] = {8'​h14,​ 8'h7f, 8'h14, 8'h7f, 8'​h14}; ​  // 35  #
 + mem[ 36] = {8'​h24,​ 8'h2a, 8'h7f, 8'h2a, 8'​h12}; ​  // 36  $
 + mem[ 37] = {8'​h62,​ 8'h64, 8'h08, 8'h13, 8'​h23}; ​  // 37  %
 + mem[ 38] = {8'​h36,​ 8'h49, 8'h55, 8'h22, 8'​h50}; ​  // 38  &
 + mem[ 39] = {8'​h00,​ 8'h05, 8'h03, 8'h00, 8'​h00}; ​  // 39  '
 + mem[ 40] = {8'​h00,​ 8'h1c, 8'h22, 8'h41, 8'​h00}; ​  // 40  (
 + mem[ 41] = {8'​h00,​ 8'h41, 8'h22, 8'h1c, 8'​h00}; ​  // 41  )
 + mem[ 42] = {8'​h14,​ 8'h08, 8'h3E, 8'h08, 8'​h14}; ​  // 42  *
 + mem[ 43] = {8'​h08,​ 8'h08, 8'h3E, 8'h08, 8'​h08}; ​  // 43  +
 + mem[ 44] = {8'​h00,​ 8'h00, 8'hA0, 8'h60, 8'​h00}; ​  // 44  ,
 + mem[ 45] = {8'​h08,​ 8'h08, 8'h08, 8'h08, 8'​h08}; ​  // 45  -
 + mem[ 46] = {8'​h00,​ 8'h60, 8'h60, 8'h00, 8'​h00}; ​  // 46  .
 + mem[ 47] = {8'​h20,​ 8'h10, 8'h08, 8'h04, 8'​h02}; ​  // 47  /
 + mem[ 48] = {8'​h3E,​ 8'h51, 8'h49, 8'h45, 8'​h3E}; ​  // 48  0
 + mem[ 49] = {8'​h00,​ 8'h42, 8'h7F, 8'h40, 8'​h00}; ​  // 49  1
 + mem[ 50] = {8'​h42,​ 8'h61, 8'h51, 8'h49, 8'​h46}; ​  // 50  2
 + mem[ 51] = {8'​h21,​ 8'h41, 8'h45, 8'h4B, 8'​h31}; ​  // 51  3
 + mem[ 52] = {8'​h18,​ 8'h14, 8'h12, 8'h7F, 8'​h10}; ​  // 52  4
 + mem[ 53] = {8'​h27,​ 8'h45, 8'h45, 8'h45, 8'​h39}; ​  // 53  5
 + mem[ 54] = {8'​h3C,​ 8'h4A, 8'h49, 8'h49, 8'​h30}; ​  // 54  6
 + mem[ 55] = {8'​h01,​ 8'h71, 8'h09, 8'h05, 8'​h03}; ​  // 55  7
 + mem[ 56] = {8'​h36,​ 8'h49, 8'h49, 8'h49, 8'​h36}; ​  // 56  8
 + mem[ 57] = {8'​h06,​ 8'h49, 8'h49, 8'h29, 8'​h1E}; ​  // 57  9
 + mem[ 58] = {8'​h00,​ 8'h36, 8'h36, 8'h00, 8'​h00}; ​  // 58  :
 + mem[ 59] = {8'​h00,​ 8'h56, 8'h36, 8'h00, 8'​h00}; ​  // 59  ;
 + mem[ 60] = {8'​h08,​ 8'h14, 8'h22, 8'h41, 8'​h00}; ​  // 60  <
 + mem[ 61] = {8'​h14,​ 8'h14, 8'h14, 8'h14, 8'​h14}; ​  // 61  =
 + mem[ 62] = {8'​h00,​ 8'h41, 8'h22, 8'h14, 8'​h08}; ​  // 62  >
 + mem[ 63] = {8'​h02,​ 8'h01, 8'h51, 8'h09, 8'​h06}; ​  // 63  ?
 + mem[ 64] = {8'​h32,​ 8'h49, 8'h59, 8'h51, 8'​h3E}; ​  // 64  @
 + mem[ 65] = {8'​h7C,​ 8'h12, 8'h11, 8'h12, 8'​h7C}; ​  // 65  A
 + mem[ 66] = {8'​h7F,​ 8'h49, 8'h49, 8'h49, 8'​h36}; ​  // 66  B
 + mem[ 67] = {8'​h3E,​ 8'h41, 8'h41, 8'h41, 8'​h22}; ​  // 67  C
 + mem[ 68] = {8'​h7F,​ 8'h41, 8'h41, 8'h22, 8'​h1C}; ​  // 68  D
 + mem[ 69] = {8'​h7F,​ 8'h49, 8'h49, 8'h49, 8'​h41}; ​  // 69  E
 + mem[ 70] = {8'​h7F,​ 8'h09, 8'h09, 8'h09, 8'​h01}; ​  // 70  F
 + mem[ 71] = {8'​h3E,​ 8'h41, 8'h49, 8'h49, 8'​h7A}; ​  // 71  G
 + mem[ 72] = {8'​h7F,​ 8'h08, 8'h08, 8'h08, 8'​h7F}; ​  // 72  H
 + mem[ 73] = {8'​h00,​ 8'h41, 8'h7F, 8'h41, 8'​h00}; ​  // 73  I
 + mem[ 74] = {8'​h20,​ 8'h40, 8'h41, 8'h3F, 8'​h01}; ​  // 74  J
 + mem[ 75] = {8'​h7F,​ 8'h08, 8'h14, 8'h22, 8'​h41}; ​  // 75  K
 + mem[ 76] = {8'​h7F,​ 8'h40, 8'h40, 8'h40, 8'​h40}; ​  // 76  L
 + mem[ 77] = {8'​h7F,​ 8'h02, 8'h0C, 8'h02, 8'​h7F}; ​  // 77  M
 + mem[ 78] = {8'​h7F,​ 8'h04, 8'h08, 8'h10, 8'​h7F}; ​  // 78  N
 + mem[ 79] = {8'​h3E,​ 8'h41, 8'h41, 8'h41, 8'​h3E}; ​  // 79  O
 + mem[ 80] = {8'​h7F,​ 8'h09, 8'h09, 8'h09, 8'​h06}; ​  // 80  P
 + mem[ 81] = {8'​h3E,​ 8'h41, 8'h51, 8'h21, 8'​h5E}; ​  // 81  Q
 + mem[ 82] = {8'​h7F,​ 8'h09, 8'h19, 8'h29, 8'​h46}; ​  // 82  R
 + mem[ 83] = {8'​h46,​ 8'h49, 8'h49, 8'h49, 8'​h31}; ​  // 83  S
 + mem[ 84] = {8'​h01,​ 8'h01, 8'h7F, 8'h01, 8'​h01}; ​  // 84  T
 + mem[ 85] = {8'​h3F,​ 8'h40, 8'h40, 8'h40, 8'​h3F}; ​  // 85  U
 + mem[ 86] = {8'​h1F,​ 8'h20, 8'h40, 8'h20, 8'​h1F}; ​  // 86  V
 + mem[ 87] = {8'​h3F,​ 8'h40, 8'h38, 8'h40, 8'​h3F}; ​  // 87  W
 + mem[ 88] = {8'​h63,​ 8'h14, 8'h08, 8'h14, 8'​h63}; ​  // 88  X
 + mem[ 89] = {8'​h07,​ 8'h08, 8'h70, 8'h08, 8'​h07}; ​  // 89  Y
 + mem[ 90] = {8'​h61,​ 8'h51, 8'h49, 8'h45, 8'​h43}; ​  // 90  Z
 + mem[ 91] = {8'​h00,​ 8'h7F, 8'h41, 8'h41, 8'​h00}; ​  // 91  [
 + mem[ 92] = {8'​h55,​ 8'h2A, 8'h55, 8'h2A, 8'​h55}; ​  // 92  .
 + mem[ 93] = {8'​h00,​ 8'h41, 8'h41, 8'h7F, 8'​h00}; ​  // 93  ]
 + mem[ 94] = {8'​h04,​ 8'h02, 8'h01, 8'h02, 8'​h04}; ​  // 94  ^
 + mem[ 95] = {8'​h40,​ 8'h40, 8'h40, 8'h40, 8'​h40}; ​  // 95  _
 + mem[ 96] = {8'​h00,​ 8'h01, 8'h02, 8'h04, 8'​h00}; ​  // 96  '
 + mem[ 97] = {8'​h20,​ 8'h54, 8'h54, 8'h54, 8'​h78}; ​  // 97  a
 + mem[ 98] = {8'​h7F,​ 8'h48, 8'h44, 8'h44, 8'​h38}; ​  // 98  b
 + mem[ 99] = {8'​h38,​ 8'h44, 8'h44, 8'h44, 8'​h20}; ​  // 99  c
 + mem[100] = {8'​h38,​ 8'h44, 8'h44, 8'h48, 8'​h7F}; ​  // 100 d
 + mem[101] = {8'​h38,​ 8'h54, 8'h54, 8'h54, 8'​h18}; ​  // 101 e
 + mem[102] = {8'​h08,​ 8'h7E, 8'h09, 8'h01, 8'​h02}; ​  // 102 f
 + mem[103] = {8'​h18,​ 8'hA4, 8'hA4, 8'hA4, 8'​h7C}; ​  // 103 g
 + mem[104] = {8'​h7F,​ 8'h08, 8'h04, 8'h04, 8'​h78}; ​  // 104 h
 + mem[105] = {8'​h00,​ 8'h44, 8'h7D, 8'h40, 8'​h00}; ​  // 105 i
 + mem[106] = {8'​h40,​ 8'h80, 8'h84, 8'h7D, 8'​h00}; ​  // 106 j
 + mem[107] = {8'​h7F,​ 8'h10, 8'h28, 8'h44, 8'​h00}; ​  // 107 k
 + mem[108] = {8'​h00,​ 8'h41, 8'h7F, 8'h40, 8'​h00}; ​  // 108 l
 + mem[109] = {8'​h7C,​ 8'h04, 8'h18, 8'h04, 8'​h78}; ​  // 109 m
 + mem[110] = {8'​h7C,​ 8'h08, 8'h04, 8'h04, 8'​h78}; ​  // 110 n
 + mem[111] = {8'​h38,​ 8'h44, 8'h44, 8'h44, 8'​h38}; ​  // 111 o
 + mem[112] = {8'​hFC,​ 8'h24, 8'h24, 8'h24, 8'​h18}; ​  // 112 p
 + mem[113] = {8'​h18,​ 8'h24, 8'h24, 8'h18, 8'​hFC}; ​  // 113 q
 + mem[114] = {8'​h7C,​ 8'h08, 8'h04, 8'h04, 8'​h08}; ​  // 114 r
 + mem[115] = {8'​h48,​ 8'h54, 8'h54, 8'h54, 8'​h20}; ​  // 115 s
 + mem[116] = {8'​h04,​ 8'h3F, 8'h44, 8'h40, 8'​h20}; ​  // 116 t
 + mem[117] = {8'​h3C,​ 8'h40, 8'h40, 8'h20, 8'​h7C}; ​  // 117 u
 + mem[118] = {8'​h1C,​ 8'h20, 8'h40, 8'h20, 8'​h1C}; ​  // 118 v
 + mem[119] = {8'​h3C,​ 8'h40, 8'h30, 8'h40, 8'​h3C}; ​  // 119 w
 + mem[120] = {8'​h44,​ 8'h28, 8'h10, 8'h28, 8'​h44}; ​  // 120 x
 + mem[121] = {8'​h1C,​ 8'hA0, 8'hA0, 8'hA0, 8'​h7C}; ​  // 121 y
 + mem[122] = {8'​h44,​ 8'h64, 8'h54, 8'h4C, 8'​h44}; ​  // 122 z
 + end
 +
 +endmodule
 +
 +</​code>​
  
 ### 通过DDS+PWM产生任意波形 ### 通过DDS+PWM产生任意波形
行 31: 行 368:
  
 ### 通过PWM产生可调电压 ### 通过PWM产生可调电压
-{{ :​fpga_pwm_dc.jpg ​|}}<WRAP centeralign> ​通过PWM产生可变直流电压的模拟电路原理图 </​WRAP>​+参见：[[pwm_dc|通过PWM生成可调直流电压]]