pwm

//pwm.c
#include <iocc2540.h>
#include "pwm.h"




//pwm pins:
//P0_3:R  (TX)--ch1
//P0_4:G  (CTS)--ch2
//P0_5:B  (RTS)--ch3
static uint16 gRed =1;
static uint16 gGreen =1;
static uint16 gBlue =1;



void PWM_Init()
{
    //设置pwm端口为输出
    P0DIR|= BV(3)|BV(4)|BV(5);
    //设置pwm端口为外设端口，非gpio
    P0SEL|= BV(3)|BV(4)|BV(5);
    //由于uart等会占用我们当前使用的pwm端口，因此需要将uart等重映射到别的端口去。
    PERCFG |= 0x03;             // Move USART1&2 to alternate2 location so that T1 is visible

    // Initialize Timer 1
    T1CTL = 0x0C;               // Div = 128, CLR, MODE = Suspended
    T1CCTL1 = 0x0C;             // IM = 0; CMP = Clear output on compare; Mode = Compare
    T1CCTL2 = 0x0C;             // IM = 0; CMP = Clear output on compare; Mode = Compare
    T1CCTL3 = 0x0C;             // IM = 0, CMP = Clear output on compare; Mode = Compare
    T1CNTL = 0;                 // Reset timer to 0;

    //必须设置，否则定时器不工作
    T1CCTL0 = 0x4C;            // IM = 1, CMP = Clear output on compare; Mode = Compare

    //设置周期的tick为375, 也就是1.5ms
#if 1
    T1CC0H = 0x01;              // Ticks = 375 (1.5ms initial duty cycle)
    T1CC0L = 0x77;              //
    T1CC1H = 0x01;              // Ticks = 375 (1.5ms initial duty cycle)
    T1CC1L = 0x77;
    T1CC2H = 0x01;              // Ticks = 375 (1.5ms initial duty cycle)
    T1CC2L = 0x77;
    T1CC3H = 0x01;              // Ticks = 375 (1.5ms initial duty cycle)
    T1CC3L = 0x77;
#else//以下设置会是1khz
#define VALUE_H     0x00
#define VALUE_L     0x10
    T1CC0H = VALUE_H;
    T1CC0L = VALUE_L;
    T1CC1H = VALUE_H;
    T1CC1L = VALUE_L;
    T1CC2H = VALUE_H;
    T1CC2L = VALUE_L;
    T1CC3H = VALUE_H;
    T1CC3L = VALUE_L;
#endif

    EA=1;
    IEN1 |= 0x02;               // Enable T1 cpu interrupt
}

//red， green， blue 的值必须是 1~375, 其他值无效
void PWM_Pulse(uint16 red, uint16 green, uint16 blue)
{
    uint16 r,g,b;

    // stop,注意，不能加这句，加了周期偏差十几倍，具体原因未查明
    //T1CTL &= BV(0)|BV(1);
    r=red;
    g=green;
    b=blue;
    // Set up the timer registers

    T1CC1L = (uint8)r;
    T1CC1H = (uint8)(r >> 8);
    //避免比较值为0时，输出一直为高
    if(r!=0)
    {
        T1CCTL1 = 0x0C;
    } else
    {
        T1CCTL1 = 0x00;
    }
    T1CC2L = (uint8)g;
    T1CC2H = (uint8)(g >> 8);
    if(g!=0)
    {
        T1CCTL2 = 0x0C;
    } else
    {
        T1CCTL2 = 0x00;
    }
    T1CC3L = (uint8)b;
    T1CC3H = (uint8)(b >> 8);
    if(b!=0)
    {
        T1CCTL3 = 0x0C;
    } else
    {
        T1CCTL3 = 0x00;
    }

    // Reset timer
    T1CNTL = 0;
    // Start timer in modulo mode.
    T1CTL |= 0x02;
}

//red， green， blue 的值必须是 1~375, 其他值无效
void PWM_RGB(uint16 red, uint16 green, uint16 blue)
{
    gRed=red;
    gGreen=green;
    gBlue=blue;
}

//#pragma register_bank=2
#pragma vector = T1_VECTOR
__interrupt void pwmISR (void)
{
    uint8 flags = T1STAT;
    // T1 ch 0
    if (flags & 0x01)
    {
        // Stop Timer 1
        //T1CTL |= 0x02;
        //red， green， blue 的值必须是 1~375, 其他值无效
        PWM_Pulse(gRed,gGreen,gBlue);
    }
    T1STAT = ~ flags;
}

//pwm.h
#ifndef __PWM_H__
#define __PWM_H__

#include <iocc2540.h>


#define uint8 unsigned char
#define uint16 unsigned short
#define BV(n)      (1 << (n))



void PWM_Init();
void PWM_Pulse(uint16 red, uint16 green, uint16 blue);
void PWM_RGB(uint16 red, uint16 green, uint16 blue);



#endif




//main.c
#include "pwm.h"

//(375/2)--------305.8-3.2-48.8
//(375)----------305.8-3.2-97.8
//(375*100/10)---
#define R_CYCLE (375/2)
#define G_CYCLE (375/2)
#define B_CYCLE (375/2)
void init_clock(void)
{
    CLKCONCMD &= ~0x40;              //设置系统时钟源为 32MHZ晶振
    while(CLKCONSTA & 0x40);         //等待晶振稳定
    CLKCONCMD &= ~0x47;              //设置系统主时钟频率为 32MHZ
}
void main(void)
{

    IEN0 = IEN1 = IEN2 = 0x00;

    init_clock();
    PWM_Init();
    PWM_RGB(R_CYCLE,G_CYCLE,B_CYCLE);
    PWM_Pulse(R_CYCLE,G_CYCLE,B_CYCLE);
    
    while(1)
    {

    }
}

教程的测试结果是周期是1.5MS，但是本人测试周期是3MS。不知道本人哪里弄错。

测试结果：

image.png