伺服不会在 FPGA 上停止

Question

我正在研究用 FPGA 制作一个伺服运行用于数字锁。

My code is as follows:
`timescale 1ns / 1ps


/*
 1 pin for servo--ORANGE CABLE
 red cable-- 5V, brown cable-- GND. 
 Position "0" (1.5 ms pulse) is middle, 
 "90" (~2ms pulse) is all the way to the right,
 "-90" (~1 ms pulse) is all the way to the left.  
 servo stuff:
 http://www.micropik.com/PDF/SG90Servo.pdf
 */


 //All i need to do is set SERVOPWM to 1 and 0 with delays i think
module ServoTestNShit(input M_CLOCK,
                             output [7:0] IO_LED, // IO Board LEDs
                             output reg SERVOPWM);    

    assign IO_LED = 7'b1010101; // stagger led lights just cause

   reg [15:0] counter;
    reg [15:0] counter1;

    initial begin 
    counter1 = 0;
    counter = 0;
    end

    //use counter to have a 1ms or 2ms or 1.5ms duty cycle for a while inorder to actually run
    //because run it this way is asking the servo to move for 1.5ms so it cant atually move that fast

    always @ (posedge M_CLOCK)
    begin
   counter <= counter+1;
    counter1 <= counter1+1;
    end


    always @ (negedge M_CLOCK)
    begin

            //if (counter1 > 500) 
            //begin
            SERVOPWM <= (counter <= 1);
            //end

    end



endmodule

目前无论发送2ms还是1ms都可以让它一直向右转。我遇到的最大问题是试图让它只在向右转弯时运行，然后停下来。我尝试过的一切最终都以根本无法工作，或者不停地工作，就像我一开始就没有将 0 发送到 pin 一样。

任何人都可以建议在足够的时间一直旋转到一个方向后向其发送 0 的最佳方法吗？

谢谢！

Answer 1

您需要通过脉宽调制 (PWM) 来调整伺服电压。换句话说，如果你想要 10% 的电压，你需要将输出引脚 SERVOPWM 设置为持续时间的 10%。

我的做法是：

module ServoTestNShit(input M_CLOCK,

                             input  [7:0] voltage_percentage,
                             output [7:0] IO_LED, // IO Board LEDs
                             output reg SERVOPWM);    
   reg [7:0] counter;


    initial begin 

    counter = 0;
    end

    // let the counter count for 100 time units
    always @ (posedge M_CLOCK)
    begin
         counter <= counter+1;
         if (counter <= 100)
            counter <= 0;
    end

    // set the output 1 for voltage_percentage/100 of the time
    always @ (negedge M_CLOCK)
    begin
            SERVOPWM <= (counter <= voltage_percentage);
    end



endmodule

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