kinetis的FTM例程——定时器模计数(查询方式)
0赞kinetis有好几种定时器,FTM是功能比较多的一种。我们先来用其模计数功能实现昨天的跑马灯功能。同样在使用FTM之前要先配置系统集成模块,打开FTM的时钟。下面介绍相关寄存器:
FTMx_MODE - 模式寄存器。
FTMx_SC - 状态和控制寄存器,设置时钟源、分频系数等。
FTMx_CNTIN - 计数初值寄存器,当溢出时从该值开始下一轮计数。
FTMx_CNT - 计数寄存器。
FTMx_MOD - 模寄存器,当计数到该值时,溢出寄存器置位,如果使能了溢出中断,将进入溢出中断服务程序。
下面是完整代码:
/*
* 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));
//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));
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_CNTIN = (uint32_t)0x00UL;//初值值0
FTM0_CNT = (uint32_t)0x00UL;//计数值0
FTM0_MOD = (uint32_t)50000;//模50000
FTM0_SC = (uint32_t)0x0FUL;//系统时钟,128分频
}
int main(void)
{
static int counter = 26;
FTM0_Init();
GPIO_Init();
printf("Hello (Kinetis) World in 'C' from PK60X256 derivative! \n\r");
for(;;)
{
if( (FTM0_SC&0x80)!=0 )
{
FTM0_SC &= ~0x80;
GPIOA_PDOR = GPIO_PDOR_PDO(GPIO_PIN(counter));
counter++;
if(counter > 29)
{
counter = 26;
}
}
}
return 0;
}
效果如下:D6->D3依次点亮