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hb_led [2021/09/13 01:58] gongyu 创建 |
hb_led [2021/10/21 21:39] (当前版本) gongyu [5. 代码设计] |
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### 5. 代码设计 | ### 5. 代码设计 | ||
+ | #### 5.1 LED按照一定频率开/关 | ||
+ | <code verilog> | ||
+ | module LEDblink(clk, LED); | ||
+ | input clk; // clock typically from 10MHz to 50MHz | ||
+ | output LED; | ||
+ | |||
+ | // create a binary counter | ||
+ | reg [31:0] cnt; | ||
+ | always @(posedge clk) cnt <= cnt+1; | ||
+ | |||
+ | assign LED = cnt[22]; // blink the LED at a few Hz (using the 23th bit of the counter, use a different bit to modify the blinking rate) | ||
+ | endmodule | ||
+ | |||
+ | </code> | ||
+ | |||
+ | #### 5.2 LED半亮 | ||
+ | 一种解决方案是将与LED串联使用的电阻器的值加倍。另一个解决方案是驱动LED FPGA输出时间的一半“足够快”,这样你的眼睛平均光,看到LED半亮。 | ||
+ | <code verilog> | ||
+ | module LEDhalflit(clk, LED); | ||
+ | input clk; | ||
+ | output LED; | ||
+ | |||
+ | reg toggle; | ||
+ | always @(posedge clk) toggle <= ~toggle; // toggles at half the clk frequency | ||
+ | |||
+ | assign LED = toggle; | ||
+ | endmodule | ||
+ | </code> | ||
+ | |||
+ | #### 5.4 精调LED的亮度 | ||
+ | 对于更多的LED强度控制,PWM是一个理想的解决方案。这里有一个例子,使用4位控制选择16个强度级别的LED。 | ||
+ | <code verilog> | ||
+ | module LED_PWM(clk, PWM_input, LED); | ||
+ | input clk; | ||
+ | input [3:0] PWM_input; // 16 intensity levels | ||
+ | output LED; | ||
+ | |||
+ | reg [4:0] PWM; | ||
+ | always @(posedge clk) PWM <= PWM[3:0] + PWM_input; | ||
+ | |||
+ | assign LED = PWM[4]; | ||
+ | endmodule | ||
+ | </code> | ||
+ | 通过不断改变LED的强度,LED看起来会“发光”。 | ||
+ | <code verilog> | ||
+ | module LEDglow(clk, LED); | ||
+ | input clk; | ||
+ | output LED; | ||
+ | |||
+ | reg [23:0] cnt; | ||
+ | always @(posedge clk) cnt <= cnt+1; | ||
+ | |||
+ | reg [4:0] PWM; | ||
+ | wire [3:0] intensity = cnt[23] ? cnt[22:19] : ~cnt[22:19]; // ramp the intensity up and down | ||
+ | always @(posedge clk) PWM <= PWM[3:0] + intensity; | ||
+ | |||
+ | assign LED = PWM[4]; | ||
+ | endmodule | ||
+ | </code> | ||
+ | |||
+ | |||
+ | #### 5.3 LED按照设定频率闪动 | ||
- | #### 5.1 设计文件 | ||
模块框图如下: | 模块框图如下: | ||
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