看到很多如何stm32用pwm信号控制舵机的文章,老生常谈了
我来写一个stm32接收pwm信号的例子 ,这个pwm信号是用来控制舵机的
背景:
我需要接收航模接收机的,用来控制舵机的pwm信号, 得到这个信号后,做其他事情.
初版代码
pwm.h
#ifndef _pwm_H
#define _pwm_H
#include "system.h"
extern uint16_t IC2Value;
extern float DutyCycle;
extern float Frequency;
void pwmIC_Init();
#endif
pwm.c
#include "pwm.h"
#include "usart.h"
#include "stm32f10x_gpio.h"
/**
me totally new
**/
void pwmIC_Init()
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_PWMIConfig(TIM3, &TIM_ICInitStructure);
TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);
TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);
TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable);
TIM_Cmd(TIM3, ENABLE);
TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE);
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
// https://blog.csdn.net/qq_37389133/article/details/79772878
/*
这里最关键的就是TIM_ICPolarity_Rising 为上升沿开始捕获，TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);
选择IC2为有效的输入端，就是IC2获得的就是周期了，而IC1就是在这里就是高电平的时间！ 假设周期：600，高电平时间：300
可以计算的得到占空比 = 300/600， 可以得到频率 =72M/ 600
*/
void TIM3_IRQHandler(void)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);
//ic2是周期
IC2Value = TIM_GetCapture2(TIM3);
if (IC2Value != 0)
{
//TIM_GetCapture1(TIM3)是高电平的时间,除以周期得到占空比
DutyCycle = (TIM_GetCapture1(TIM3) * 100) / IC2Value;
Frequency = SystemCoreClock / IC2Value;
}
else
{
DutyCycle = 0;
Frequency = 0;
}
}
代码参考了:
https://blog.csdn.net/qq_37389133/article/details/79772878
代码是可以用的,
只需要在main.c里引用pwm.h然后定义extern变量 然后在初始化的地方执行pwmIC_Init(); 之后就可以用这几个变量了
但问题是:
dutycycle到101左右之后就又从零开始了.
跟踪到TIM_GetCapture1(TIM3) ,发现他到65xxx就开始变成0 , 查询了下返回类型是uint16_t
问AI
ai说%d虽然也可以但最好用%u, 还说了最大6xxxx,所以是我们的上升沿的计数超过了这个库函数的最大值,所以从0开始了. 咋办呢咋办呢,哦对了
问AI
ai告诉我可以配置定时器TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure.
我配了, 效果
是满足了我的需要的
真棒
原来我痛苦于低级语言的低级,现在我在AI的帮助下得心应手.
init的完整代码:
void pwmIC_Init()
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
//start
// 启用定时器时钟
//RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
// 配置定时器基本参数
//TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_TimeBaseStructure.TIM_Period = 0xFFFF; // 设置自动重装载寄存器为最大值
TIM_TimeBaseStructure.TIM_Prescaler = 72 - 1; // 设置预分频器为72-1
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; // 设置时钟分频因子为1
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; // 向上计数模式
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
//end
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_PWMIConfig(TIM3, &TIM_ICInitStructure);
TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);
TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);
TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable);
TIM_Cmd(TIM3, ENABLE);
TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE);
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
