pwm_counter.vhd

PWM信号产生代码

--/*****************************************************************************
-- * 源文件:	pwm_counter.vhd
-- * 模块:   	PWM信号产生
-- * 版权:
-- *         	Copyright(C) 北京联华众科科技有限公司
-- *						www.lianhua-zhongke.com.cn
-- * 版本：  	Version 1.0
-- * 
-- * 功能说明:
-- *		   	根据参数指定频率和占空比产生PWM信号，并通过串口将PWM参数发送
-- *			PC上运行的联华众科通信通显示。
-- *			串口工作参数：
-- *			波特率： 9600
-- *			数据位数： 8
-- *			奇偶位： 无
-- *			停止位： 1
-- *
-- * 参数说明：
-- *	       	输出
-- *			data - 待发送的 PWM信号参数
-- *			s_50ms - 定时发送数据的时钟
-- *			s_out - PWM信号输出
-- *
-- *			输入
-- *			clock - 波特率频率*2
-- *			reset - 复位信号，低电平有效
-- *
-- *			参数
-- *			T - PWM周期
-- *			Th - PWM正半周期宽度
-- *			inner_counter_width - 内部计数器变量位数，可容纳 T即可
-- *			send_witdh - 定时发送数据的时钟的宽度
-- *			send_counter_bits - 内部计数器变量位数，用以产生定时
-- *								   发送数据的时钟
-- *
-- * 变更记录: 
-- *         2006.01.28, 新建
-- *
-- *****************************************************************************/
LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.std_logic_arith.all;
USE ieee.std_logic_unsigned.all;

ENTITY pwm_counter IS
	GENERIC
	(
		T : INTEGER:= 24000;
		Th : INTEGER:= 2400;
		inner_counter_width : INTEGER:= 32;
		
		send_witdh : INTEGER:= 1200000;
		send_counter_bits : INTEGER:= 32
	);
	
	PORT
	(
		data : OUT STD_LOGIC_VECTOR(7 downto 0):= "00000000";		
		send_timer : OUT STD_LOGIC;		
		pwm_out : OUT STD_LOGIC;
		
		clock : IN STD_LOGIC;
		reset : IN STD_LOGIC
	);

END pwm_counter;


ARCHITECTURE pwm_architecture OF pwm_counter IS	
	SIGNAL byte_index : INTEGER RANGE 0 TO 31:=0;
BEGIN
	PROCESS(byte_index)
		--VARIABLE byte_index : STD_LOGIC_VECTOR(3 downto 0);
		
		VARIABLE full_data : STD_LOGIC_VECTOR(31 downto 0):= X"00000000";
		VARIABLE idata : STD_LOGIC_VECTOR(3 downto 0):= "0000";
	BEGIN		
		IF (byte_index = 0) THEN
			data <= X"71";--pwm generate cmd
		ELSIF (byte_index>=17 AND byte_index<=19) THEN
			data <= X"5A";--"Z"
		ELSE
			IF (byte_index>=1 AND byte_index<=8) THEN
				full_data := CONV_STD_LOGIC_VECTOR(T, 32);
			ELSE
				full_data := CONV_STD_LOGIC_VECTOR(Th, 32);
			END IF;
			
			IF (byte_index=1 OR byte_index=9) THEN idata := full_data(3 downto 0);
			ELSIF (byte_index=2 OR byte_index=10) THEN idata := full_data(7 downto 4);
			ELSIF (byte_index=3 OR byte_index=11) THEN	idata := full_data(11 downto 8);
			ELSIF (byte_index=4 OR byte_index=12) THEN	idata := full_data(15 downto 12);
			ELSIF (byte_index=5 OR byte_index=13) THEN	idata := full_data(19 downto 16);
			ELSIF (byte_index=6 OR byte_index=14) THEN	idata := full_data(23 downto 20);
			ELSIF (byte_index=7 OR byte_index=15) THEN	idata := full_data(27 downto 24);
			ELSIF (byte_index=8 OR byte_index=16) THEN	idata := full_data(31 downto 28);
			ELSE idata := "0000";
			END IF;
			
			data <= X"00";
			CASE idata IS
				WHEN "0000" => data <= X"30";
				WHEN "0001" => data <= X"31";
				WHEN "0010" => data <= X"32";
				WHEN "0011" => data <= X"33";
				WHEN "0100" => data <= X"34";
				WHEN "0101" => data <= X"35";
				WHEN "0110" => data <= X"36";
				WHEN "0111" => data <= X"37";
				WHEN "1000" => data <= X"38";
				WHEN "1001" => data <= X"39";
				WHEN "1010" => data <= X"41";
				WHEN "1011" => data <= X"42";
				WHEN "1100" => data <= X"43";
				WHEN "1101" => data <= X"44";
				WHEN "1110" => data <= X"45";
				WHEN "1111" => data <= X"46";
				WHEN OTHERS => data <= X"00";
			END CASE;
		END IF;							
	END PROCESS;
	
	PROCESS(clock, reset)
		VARIABLE delay_counter : INTEGER RANGE 0 TO T-1;
		VARIABLE send_counter : INTEGER RANGE 0 TO send_witdh-1;
	BEGIN		
		IF (reset = '0') THEN
			pwm_out <= '1';
			delay_counter := 0;
			send_counter := 0;
			byte_index <= 0;
		ELSIF(clock = '1' AND clock'EVENT) THEN
			IF (delay_counter = Th-1) THEN
				pwm_out <= '0';
				delay_counter := delay_counter+1;
			ELSIF(delay_counter = T-1) THEN
				pwm_out <= '1';
				delay_counter := 0;
			ELSE
				delay_counter := delay_counter+1;
			END IF;
				
			IF (send_counter = send_witdh-1) THEN
				send_timer <= '0';
				send_counter := 0;	
			ELSIF (send_counter = send_witdh/2-1) THEN
				send_timer <= '1';
				send_counter := send_counter+1;							
					
				IF (byte_index = 17) THEN
					byte_index <= 0;
				ELSE
					byte_index <= byte_index + 1;
				END IF;
			ELSE
				send_counter := send_counter+1;
			END IF;
		END IF;
		
	END PROCESS;

END pwm_architecture;