kinetis的FTM例程——输出比较和PWM

发表于 8/27/2012 5:10:45 PM 阅读（5005）

FTM不仅能简单计数，还可以进行通道操作，当计数到通道比较值时可“置高、置低、翻转引脚”或是PWM输出。

FTMx_CnSC －通道状态和控制寄存器，用来设置通道模式和读取通道状态。

FTMx_CnV －通道值寄存器，用来设置比较值。

下面的例子在实现跑马灯基础上，实现２路比较输出和１路PWM输出。

/*
* main implementation: use this 'C' sample to create your own application
*
*/

#define GPIO_PIN_MASK 0x3C000000
#define GPIO_PIN(x) ((1<<x)&GPIO_PIN_MASK)

#include <stdio.h>
#include "derivative.h" /* include peripheral declarations */

void delay()
{
    int i =0;
    int j=0;
    for(i=0;i<3000;i++)
      for(j=0;j<1000;j++)
          asm("nop");
}
void GPIO_Init()
{
    SIM_SCGC5 = SIM_SCGC5_PORTA_MASK | SIM_SCGC5_PORTB_MASK | SIM_SCGC5_PORTC_MASK | SIM_SCGC5_PORTD_MASK | SIM_SCGC5_PORTE_MASK;
    /* Set GPIOA pin26~29 as GPIO*/
    PORTA_PCR26=(PORT_PCR_MUX(1));
    PORTA_PCR27=(PORT_PCR_MUX(1));
    PORTA_PCR28=(PORT_PCR_MUX(1));
    PORTA_PCR29=(PORT_PCR_MUX(1));
    PORTA_PCR5=(PORT_PCR_MUX(3));
    PORTA_PCR6=(PORT_PCR_MUX(3));
    PORTA_PCR7=(PORT_PCR_MUX(3));
    //set GPIOA pin26~29 to be output
    GPIOA_PDDR=GPIO_PDDR_PDD(GPIO_PIN(26))
         | GPIO_PDDR_PDD(GPIO_PIN(27))
         | GPIO_PDDR_PDD(GPIO_PIN(28))
         | GPIO_PDDR_PDD(GPIO_PIN(29))
         | GPIO_PDDR_PDD(GPIO_PIN(5))
         | GPIO_PDDR_PDD(GPIO_PIN(6))
         | GPIO_PDDR_PDD(GPIO_PIN(7));
    GPIOA_PDOR = 0;//所有LED灭
}
void FTM0_Init()
{
    SIM_SCGC6 |= (uint32_t)0x01000000UL;
    FTM0_MODE = (uint32_t)0x04UL;
    FTM0_SC = (uint32_t)0x00UL;
    FTM0_C2SC = 0x68;    //PWM模式，匹配时引脚翻转并产生中断
    FTM0_C2V = 20000;
    FTM0_C3SC = 0x14;    //输出比较模式，匹配时引脚翻转，不产生中断
    FTM0_C3V = 10000;
    FTM0_C4SC = 0x14;    //输出比较模式，匹配时引脚翻转，不产生中断
    FTM0_C4V = 30000;

    FTM0_CNTIN = (uint32_t)0;//初值值0
    FTM0_CNT = (uint32_t)0;//计数值0
    FTM0_MOD = (uint32_t)50000;//模50000
    FTM0_SC = (uint32_t)0x0FUL;//系统时钟，128分频
    NVICISER1 |= (uint32_t)0x40000000UL;//使能中断NVICISERn=m,其中n=62/32,m=62%32
}
int main(void)
{
    static int counter = 26;
    FTM0_Init();
    GPIO_Init();
    printf("Hello (Kinetis) World in 'C' from PK60X256 derivative! \n\r");
    for(;;)
    {

    }
    return 0;
}
void FTM0_Interrupt(void)
{
    unsigned int tmp;
    static int counter = 26;

    tmp = FTM0_SC;
    if( (tmp&0x80) !=0)
    {
        FTM0_SC &= ~0x80;
    }
    tmp = FTM0_C2SC;
    if( (tmp&0x80)!=0 )
    {
        FTM0_C2SC &= ~0x80;
    }
    GPIOA_PDOR = GPIO_PDOR_PDO(GPIO_PIN(counter));
    counter++;
    if(counter > 29)
    {
        counter = 26;
    }
}