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输出比较可以通过比较CNT(时基单元内的计数器)与CCR(捕获比较寄存器)值的关系,来对输出电平进行置1、置O或翻转的操作,用于输出一定频率和占空比的PWM波形(用于输出PWM波形)。
PWM (Pulse Width Modulation) 脉冲宽度调制在具有惯性的系统中,可以通过对一系列脉冲的宽度进行调制,来等效地获得所需要的模拟参量,常应用于电机控速等领域;
(蓝色线是CNT 黄色线是ARR 红色线是CCR 绿色线是输出高低电平)
PWM参数:
频率=1/Ts 占空比= Ton/Ts 分辨率 =占空比变化步距
ARR、PSC、CCR三个共同决定输出PWM的周期和占空比
PWM频率:Freg = CK PSC /(PSC + 1) /(ARR + 1)
PWM占空比:Duty = CCR /(ARR +1)
PWM分辨率:Reso =1/(ARR +1)
输出PWM步骤:
①RCC开启时钟,将TIM外设和GPIO外设的时钟打开;
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
②配置时基单元包括其前面的时钟源选择;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
- TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
- TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
- TIM_TimeBaseInitStructure.TIM_Period = 10000 - 1; //ARR
- TIM_TimeBaseInitStructure.TIM_Prescaler = 7200 - 1; //PSC
- TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
- TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStructure);
③配置输出比较单元,里面包括CCR的值、输出比较模式。极性选择、输出使能这些参数;
需要注意的是有四个输出比较单元也叫输出比较通道,输出比较单元的选择根据自身选取的GPIO口需求来确定
- TIM_OCInitTypeDef TIM_OCInitStructure;
- TIM_OCStructInit(&TIM_OCInitStructure);//给结构体赋初始值(帮忙给全部成员赋值,因为下面并没有给全部成员赋初值)
- TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;//输出比较的模式
- TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//输出比较的极性
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//输出使能
- TIM_OCInitStructure.TIM_Pulse = 0; //设置CCR
- TIM_OC1Init(TIM2, &TIM_OCInitStructure);
④ 配置GPIO,将PWM对应的GPIO口,初始化为复用推挽输出的配置;
- GPIO_InitTypeDef GPIO_InitStructure;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//需选择为复用推挽输出
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //也可以用重映射功能到PA15,重映射要用到AFIO
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_Init(GPIOA, &GPIO_InitStructure);
重映射的管脚选择引脚重映射函数:配置重映射是用AFIO来完成的
- * @arg GPIO_PartialRemap1_TIM2 : TIM2 Partial1 Alternate Function mapping
- * @arg GPIO_PartialRemap2_TIM2 : TIM2 Partial2 Alternate Function mapping
- * @arg GPIO_FullRemap_TIM2 : TIM2 Full Alternate Function mapping
- //部分重映射1、部分重映射2、完全重映射
解除端口复用的三种方式:
SWJ是SWD和JTAG两种调试方法
1、就是解除JTRST引脚的复用(PB4)
2、解除JTAG调试端口的复用(PA15、PB3、PB4)保留SWD(PA13、PA14)
3、解除SWD和JTAG两种 (1和2)
- * @arg GPIO_Remap_SWJ_NoJTRST : Full SWJ Enabled (JTAG-DP + SW-DP) but without JTRST
- * @arg GPIO_Remap_SWJ_JTAGDisable : JTAG-DP Disabled and SW-DP Enabled
- * @arg GPIO_Remap_SWJ_Disable : Full SWJ Disabled (JTAG-DP + SW-DP)
这里原先引脚为PA0,复用到PA15,又因为PA15开始默认为调试端口JTDI,想要将其变成普通的GPIO或复用定时器通道就要先关闭调试端口的复用。
先使能AFIO复用功能,解除JTAG调试端口,然后重映射定时器(其他外设的复用引脚)
- // 重映射功能
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
- GPIO_PinRemapConfig(GPIO_PartialRemap1_TIM2, ENABLE);
- //要先关闭调试端口的复用
- GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable, ENABLE);
⑤运行控制,启动计数器;
TIM_Cmd(TIM2, ENABLE);
代码了解
- //用来结构体来初始化输出比较单元
- void TIM_OC1Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC2Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC3Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC4Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- //用来配置强制输出模式
- void TIM_ForcedOC1Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC2Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC3Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC4Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- //外部事件时清除REF信号
- void TIM_ClearOC1Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC2Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC3Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC4Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- //配置快速使能
- void TIM_OC1FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC2FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC3FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC4FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- //用来配置CCR寄存器的预装功能(影子寄存器)
- void TIM_OC1PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC2PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC3PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC4PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- //单独设置输出比较的极性(带N的是高级定时器里互补通道的配置 OC4没有互补通,所以没有OC4N函数)
- void TIM_OC1PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC1NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC2PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC2NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC3PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC3NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC4PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- //单独修改输出使能参数
- void TIM_CCxCmd(TIM_TypeDef* TIMx, uint16_t TIM_Channel, uint16_t TIM_CCx);
- void TIM_CCxNCmd(TIM_TypeDef* TIMx, uint16_t TIM_Channel, uint16_t TIM_CCxN);
- //单独更改CCR寄存器值的函数
- void TIM_SetCompare1(TIM_TypeDef* TIMx, uint16_t Compare1);
- void TIM_SetCompare2(TIM_TypeDef* TIMx, uint16_t Compare2);
- void TIM_SetCompare3(TIM_TypeDef* TIMx, uint16_t Compare3);
- void TIM_SetCompare4(TIM_TypeDef* TIMx, uint16_t Compare4);
- //仅高级定时器使用,在使用高级定时器输出PWM时需要调用,否则PWM不能正常输出
- void TIM_CtrlPWMOutputs(TIM_TypeDef* TIMx, FunctionalState NewState);
- //
-
-
- //用来结构体来初始化输出比较单元
- void TIM_OC1Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC2Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC3Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- void TIM_OC4Init(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
- //用来配置强制输出模式
- void TIM_ForcedOC1Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC2Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC3Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- void TIM_ForcedOC4Config(TIM_TypeDef* TIMx, uint16_t TIM_ForcedAction);
- //外部事件时清除REF信号
- void TIM_ClearOC1Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC2Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC3Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- void TIM_ClearOC4Ref(TIM_TypeDef* TIMx, uint16_t TIM_OCClear);
- //配置快速使能
- void TIM_OC1FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC2FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC3FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- void TIM_OC4FastConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCFast);
- //用来配置CCR寄存器的预装功能(影子寄存器)
- void TIM_OC1PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC2PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC3PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- void TIM_OC4PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
- //单独设置输出比较的极性(带N的是高级定时器里互补通道的配置 OC4没有互补通,所以没有OC4N函数)
- void TIM_OC1PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC1NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC2PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC2NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC3PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- void TIM_OC3NPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCNPolarity);
- void TIM_OC4PolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
- //单独修改输出使能参数
- void TIM_CCxCmd(TIM_TypeDef* TIMx, uint16_t TIM_Channel, uint16_t TIM_CCx);
- void TIM_CCxNCmd(TIM_TypeDef* TIMx, uint16_t TIM_Channel, uint16_t TIM_CCxN);
- //单独更改CCR寄存器值的函数
- void TIM_SetCompare1(TIM_TypeDef* TIMx, uint16_t Compare1);
- void TIM_SetCompare2(TIM_TypeDef* TIMx, uint16_t Compare2);
- void TIM_SetCompare3(TIM_TypeDef* TIMx, uint16_t Compare3);
- void TIM_SetCompare4(TIM_TypeDef* TIMx, uint16_t Compare4);
- //仅高级定时器使用,在使用高级定时器输出PWM时需要调用,否则PWM不能正常输出
- void TIM_CtrlPWMOutputs(TIM_TypeDef* TIMx, FunctionalState NewState);
- //选择输出比较模式
- void TIM_SelectOCxM(TIM_TypeDef* TIMx, uint16_t TIM_Channel, uint16_t TIM_OCMode);
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