版权声明:转载记得声明~~~ :) https://blog.csdn.net/ReCclay/article/details/87645901
工程可见Github1<传送门>
一、主要代码
main.c
/*******************************************************************************
* 文件名:main.c
* 描 述:
* 作 者:CLAY
* 版本号:v1.0.0
* 日 期: 2019年2月18日
* 备 注:修改后的LCD例程
* PA1 (TIM2_CH2) 输出频率500Hz,占空比60%的方波
* 不过采用的是输出比较的方式
*******************************************************************************
*/
#include "stm32f10x.h"
#include "lcd.h"
#include "e2prom.h"
#include "stdio.h"
#include "i2c.h"
#include "adc.h"
#include "rtc.h"
#include "usart2.h"
#include "pwm.h"
#include "pwm_oc.h"
u32 TimingDelay = 0;
u8 RxdCnt = 0;
u8 RxdOver = 0;
u8 RxdBuf[20];
void Delay_Ms(u32 nTime);
u8 RTC_Flag = 0;
//Main Body
int main(void)
{
STM3210B_LCD_Init();
LCD_Clear(Blue);
LCD_SetBackColor(Blue);
LCD_SetTextColor(White);
SysTick_Config(SystemCoreClock/1000);
//PWM_Init(500, 60);//500Hz 60%方波
PWM_OC_Init(500, 60);//500Hz 60%方波
while(1)
{
}
}
//
void Delay_Ms(u32 nTime)
{
TimingDelay = nTime;
while(TimingDelay != 0);
}
pwm_oc.c
#include "stm32f10x.h"
u32 CH2_Val;
u32 CH2_Duty;//我日哦,溢出了注意这里是占空比对应的计数值并不是小于100的数!!!
void PWM_OC_Init(u32 freq, u8 duty)
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
CH2_Val = 1000000 / freq;//频率对应的计数值
CH2_Duty = CH2_Val * duty / 100;//占空比对应的计数值
//别忘了先开启对应时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//强推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
//输出比较需要用到定时器中断,所以设置了中断向量
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_TimeBaseStructure.TIM_Period = 0xFFFF;//总的值设置为0xFFFF
TIM_TimeBaseStructure.TIM_Prescaler = 71;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;//转换模式
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = CH2_Val;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
TIM_OC2Init(TIM2, &TIM_OCInitStructure);//注意这里是OC2
TIM_SetCounter(TIM2, 0);//计数器清0
TIM_SetCompare2(TIM2, 0);//设置比较值
TIM_Cmd(TIM2, ENABLE);//开启定时器
TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);//开启定时器中断
}
pwm_oc.h
#ifndef _PWM_OC_H
#define _PWM_OC_H
void PWM_OC_Init(u32 freq, u8 duty);
#endif
stm32f10x_it.c
...
extern u32 CH2_Val;
extern u32 CH2_Duty;
void TIM2_IRQHandler(void)
{
u16 capture = 0;
static u8 flag = 0;
if(TIM_GetITStatus(TIM2, TIM_IT_CC2) == 1)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
capture = TIM_GetCapture2(TIM2);//获取通道2的当前的比较值
if(flag)
{
TIM_SetCompare2(TIM2, capture+CH2_Duty);//设置通道2的值为:当前比较值+高电平
}
else
{
TIM_SetCompare2(TIM2, capture+(CH2_Val-CH2_Duty));//设置通道2的值为:当前比较值+低电平
}
flag ^= 1;//flag在0和1直接变化
}
}
...
二、注意事项
参考例程路径:嵌入式设计与开发项目加密资料\嵌入式设计与开发\STM32固件库v3.5\stm32f10x_stdperiph_lib\STM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\TIM\TIM9_OCToggle\main.c
1、注意CH2_Duty的定义范围
u32 CH2_Duty;
//我日哦,溢出了注意这里是占空比对应的计数值并不是小于100的数!!!
2、引脚产生PWM波,因此我们要配置为复用推挽输出模式
3、关于周期设定
计数值设置成0xFFFF
TIM_TimeBaseStructure.TIM_Period = 0xFFFF;//总的值设置为0xFFFF
pulse就相当于我们设定的周期值,在一个pulse内,小于Duty为高电平,大于Duty为低电平
TIM_OCInitStructure.TIM_Pulse = CH2_Val;
4、输出比较
定时器的计数值一直向上计数的同时,他要不断的跟我们设定的pulse和Duty做比较,所以叫输出比较。