
本例程出自STM32MED1开发板附带光盘,其工程目录路径为:\Code Package\Peripheral Devices\06 TIM\0603_PWM_Output。 % U5 ^$ j" X" X' D; j1 M" ?, g0 | 高级定时器TIM1的通道1位于GPIOA.8引脚,此管脚正好与开发板上LED1相连,这样就可以通过观察LED1亮度变化来判断TIM1的PWM输出波形变化情况。 通过调用函数TIM1_PWMOutputConfig()可对TIM1的PWM输出进行配置。其代码定义如下: 6 k! ]+ y, y& G' O7 B, u void TIM1_PWMOutputConfig(u16 Period)- d) I, y4 u6 O! Z: u. B( X+ l* j+ ^) B { TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; GPIO_InitTypeDef GPIO_InitStructure; TIM_OCInitTypeDef TIM_OCInitStructure; NVIC_InitTypeDef NVIC_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1, ENABLE); // 1). Q: A; ]3 S0 ] // (2 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;3 |$ B& O4 J) s8 ? GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;+ R3 l( R2 _# G5 g. N1 @ GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;9 |( N- F, D% U5 Q! g/ M4 U GPIO_Init(GPIOA, &GPIO_InitStructure);% a4 H# {; ^, V4 O% j // 2)6 h! c N: G" x" C // (3 TIM_TimeBaseStructure.TIM_Period = Period;! r5 X) M3 F* o# _( q' e! h. ^% L TIM_TimeBaseStructure.TIM_Prescaler = (u16)(SystemCoreClock / 100000) - 1; TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_RepetitionCounter = 0; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;# D& P& |! a% H* U6 p. S TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); // 3)2 a, @$ T& G: B6 @& H8 R* r/ C - \4 u. B! _1 b+ ~ // (40 ~+ j* ~1 w: K9 I& e4 F0 u TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;& ~$ H' T b: L a- r. Y! e TIM_OCInitStructure.TIM_Pulse = 0;9 S$ E/ M& T6 Z2 M TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;4 y0 ^$ f+ n1 J TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable; TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;: M7 T3 |% J; Z8 |1 X& v" F6 V TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; f* \7 W+ O9 g/ R G TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset; TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;0 F! L4 n/ o( N8 y; I* t `% u* Z TIM_OC1Init(TIM1, &TIM_OCInitStructure);) m- s9 d L) t" k b5 Y // 4)7 g4 ^3 }- b$ N6 i( U8 \% O+ x/ X TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Disable); // 5)" E5 ]1 X9 ~3 G; ^. Y9 l' P/ v " y* y& O/ y1 H8 v) a TIM_ClearFlag(TIM1, TIM_FLAG_Update); // 6) TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE); // 7)5 L) B5 P6 l, K" Z1 }: l7 Q0 }! a- ~ TIM_UpdateRequestConfig(TIM1, TIM_UpdateSource_Global); // 8)( f2 u0 D) b! s + U5 a, M" z/ ?$ C* v // (9 NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;7 J( `" L3 p1 x6 J0 V" W* z& H) C NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;1 R; w$ A# E" r4 _; E# O5 K NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;% }* ?2 f( ]" k, d) C- ] NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;- D% { e) u# m NVIC_Init(&NVIC_InitStructure); // 9) TIM_CtrlPWMOutputs(TIM1, ENABLE); // 10) ' J+ u2 u$ M$ c' @ TIM_Cmd(TIM1, ENABLE); // 11) }/ r6 ~: `* \$ X/ z8 Z : [# n9 z$ U* u9 t 代码行1)开启GPIOA及TIM1外设的时钟。代码段2)将PA.8管脚配置为复用推挽输出,因此TIM1产生的PWM信号能输出到PA.8管脚。代码段3)是对TIM1的时间基配置。代码段4)配置TIM1的输出比较通道1,将其配置为PWM模式2;起始寄存器TIM1_CCR1的值设为0;开启OC1的输出状态,关闭OC1的互补输出状态。代码行5)关闭OC1通道的预装载功能,使得每次向捕获/比较寄存器中写入的数据立即生效。代码行6)是清除TIM1的更新标志位。代码行7)是开启TIM1的更新中断,代码行8)将更新事件源限制为计时器的上溢或下溢。代码行9)是对TIM1的中断通道进行初始化。代码行10)是开启TIM1的PWM输出。代码行11)是使能TIM1外设。7 u6 P, w) j9 m+ H 当TIM1计数器的值达到最大时就会产生更新中断,其中断处理函数定义如下: 6 q& ?# u( y2 @7 Z D1 { void TIM1_UP_IRQHandler(void) { if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET) {( x5 `0 A4 V' p 6 S0 y+ l0 N0 i: b _4 p <span style="color: rgb(0, 0, 255);"> if ((CompareValue > PRELOAD_VALUE - INCREMENTS) || (CompareValue |
RE:STM32MED1开发板例程解析(二):定时器的PWM输出