蓝桥杯嵌入式——第六届决赛-电压测量与互补PWM 信号输出
一、赛题分析
这一届的国赛，整体说来没有什么难度，逻辑以及外设的配置都很easy。但是涉及到一个新的考点，这个需要注意一下，使用高级定时器TIM1输出互补的PWM波，主要是之前没有接触过，但是只要配置出来了，这套题就太简单了。
二、问题总结
唯一遇到的一个问题就是，之前没有配置过高级定时器1，下面给出高级定时器TIM1输出互补的PWM波的程序：
/**
* @brief Configures the different system clocks.
* @param None
* @retval None
*/
void PWM_RCC_Configuration(void)
{
/* TIM1, GPIOA and GPIOB clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE);
}
/**
* @brief Configures TIM1, TIM3 and TIM4 Pins.
* @param None
* @retval None
*/
void PWM_GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* GPIOA Configuration: TIM1 Channel2 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* GPIOB Configuration: TIM1 Channel2 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14;
GPIO_Init(GPIOB, &GPIO_InitStructure);
}
void pwm_init(uint16_t period,uint16_t pulse, FunctionalState NewState)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
TIM_DeInit(TIM1);
if(NewState == ENABLE)
{
/* System Clocks Configuration */
PWM_RCC_Configuration();
/* GPIO Configuration */
PWM_GPIO_Configuration();
/* TIM1 Peripheral Configuration ----------------------------------------*/
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 5;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 12000000 / period;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 4;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
/* Channel 2 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_Pulse = (uint16_t)(12000000 / period / 100 * pulse);
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OC2Init(TIM1, &TIM_OCInitStructure);
/* TIM1 counter enable */
TIM_Cmd(TIM1, ENABLE);
TIM_CtrlPWMOutputs(TIM1, ENABLE);
}
}