DA芯片先输出高电平,延时一下,再输出低电平,再延时一下,如此反复就是方波。
三角波、正弦波一个道理。
- /* Includes ------------------------------------------------------------------*/
- #include "stm32f4_discovery.h"
- #include <stdio.h>
- /* Private typedef -----------------------------------------------------------*/
- GPIO_InitTypeDef GPIO_InitStructure;
- USART_InitTypeDef USART_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- TIM_OCInitTypeDef TIM_OCInitStructure;
- /* Private define ------------------------------------------------------------*/
- // This is the magic number used to increment the phase accumulator
- #define R 107374182
- /* Private macro -------------------------------------------------------------*/
- /* Private variables ---------------------------------------------------------*/
- uint16_t sinetable[] = {
- 127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
- 242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
- 221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
- 76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
- 33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124
- };
- uint16_t pulse_width = 128;
- uint32_t phase_accumulator = 0;
- uint8_t angle = 0;
- /* Private function prototypes -----------------------------------------------*/
- void TIM_Config(void);
- void PWM_Config(int period);
- void PWM_SetDC(uint16_t channel,uint16_t dutycycle);
- void Delay(__IO uint32_t nCount);
- void LED_Config(void);
- void INTTIM_Config(void);
- /* Private functions ---------------------------------------------------------*/
- void TIM2_IRQHandler(void)
- {
- if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
- {
- GPIO_SetBits(GPIOD, GPIO_Pin_13);
- PWM_SetDC(1,pulse_width);
- // Calculate a new pulse width
- phase_accumulator+=R;
- angle=(uint8_t)(phase_accumulator>>24);
- pulse_width = sinetable[angle];
- TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
- GPIO_ResetBits(GPIOD, GPIO_Pin_13);
- }
- }
- /**
- * @brief Main program
- * @param None
- * @retval None
- */
- int main(void)
- {
- /* TIM Configuration */
- TIM_Config();
- /* LED Configuration */
- LED_Config();
- /* PWM Configuration */
- PWM_Config(256);
- /* Sampling rate timer */
- INTTIM_Config();
- PWM_SetDC(1,128);
- PWM_SetDC(2,128);
- PWM_SetDC(3,128);
- PWM_SetDC(4,128);
- while (1)
- {
- // Wait for sampling clock to overflow
- if (TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != RESET)
- {
-
- }
- }
- }
- /**
- * @brief Configure the TIM3 Ouput Channels.
- * @param None
- * @retval None
- */
- void TIM_Config(void)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- /* TIM3 clock enable */
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
- /* GPIOC and GPIOB clock enable */
- RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOB, ENABLE);
- /* GPIOC Configuration: TIM3 CH1 (PC6) and TIM3 CH2 (PC7) */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 ;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
- GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
- GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
- GPIO_Init(GPIOC, &GPIO_InitStructure);
- /* GPIOB Configuration: TIM3 CH3 (PB0) and TIM3 CH4 (PB1) */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
- GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
- GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
- GPIO_Init(GPIOB, &GPIO_InitStructure);
- /* Connect TIM3 pins to AF2 */
- GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);
- GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM3);
- GPIO_PinAFConfig(GPIOB, GPIO_PinSource0, GPIO_AF_TIM3);
- GPIO_PinAFConfig(GPIOB, GPIO_PinSource1, GPIO_AF_TIM3);
- }
- void PWM_Config(int period)
- {
- uint16_t PrescalerValue = 0;
- /* -----------------------------------------------------------------------
- TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles.
-
- In this example TIM3 input clock (TIM3CLK) is set to 2 * APB1 clock (PCLK1),
- since APB1 prescaler is different from 1.
- TIM3CLK = 2 * PCLK1
- PCLK1 = HCLK / 4
- => TIM3CLK = HCLK / 2 = SystemCoreClock /2
-
- To get TIM3 counter clock at 28 MHz, the prescaler is computed as follows:
- Prescaler = (TIM3CLK / TIM3 counter clock) - 1
- Prescaler = ((SystemCoreClock /2) /28 MHz) - 1
-
- To get TIM3 output clock at 30 KHz, the period (ARR)) is computed as follows:
- ARR = (TIM3 counter clock / TIM3 output clock) - 1
- = 665
- Note:
- SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f4xx.c file.
- Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()
- function to update SystemCoreClock variable value. Otherwise, any configuration
- based on this variable will be incorrect.
- ----------------------------------------------------------------------- */
- /* No prescale, run at maximum frequency */
- PrescalerValue = 0;
- /* Time base configuration */
- TIM_TimeBaseStructure.TIM_Period = period;
- TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
- TIM_TimeBaseStructure.TIM_ClockDivision = 0;
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
- TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
- /* PWM1 Mode configuration: Channel1 */
- TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = 0;
- TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
- TIM_OC1Init(TIM3, &TIM_OCInitStructure);
- TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
- /* PWM1 Mode configuration: Channel2 */
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = 0;
- TIM_OC2Init(TIM3, &TIM_OCInitStructure);
- TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
- /* PWM1 Mode configuration: Channel3 */
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = 0;
- TIM_OC3Init(TIM3, &TIM_OCInitStructure);
- TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
- /* PWM1 Mode configuration: Channel4 */
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = 0;
- TIM_OC4Init(TIM3, &TIM_OCInitStructure);
- TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);
- TIM_ARRPreloadConfig(TIM3, ENABLE);
- /* TIM3 enable counter */
- TIM_Cmd(TIM3, ENABLE);
- }
- void PWM_SetDC(uint16_t channel,uint16_t dutycycle)
- {
- if (channel == 1)
- {
- TIM3->CCR1 = dutycycle;
- }
- else if (channel == 2)
- {
- TIM3->CCR2 = dutycycle;
- }
- else if (channel == 3)
- {
- TIM3->CCR3 = dutycycle;
- }
- else
- {
- TIM3->CCR4 = dutycycle;
- }
- }
- void LED_Config(void)
- {
- /* GPIOD Periph clock enable */
- RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
- /* Configure PD12, PD13, PD14 and PD15 in output pushpull mode */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13| GPIO_Pin_14| GPIO_Pin_15;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
- GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
- GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
- GPIO_Init(GPIOD, &GPIO_InitStructure);
- }
- void INTTIM_Config(void)
- {
- NVIC_InitTypeDef NVIC_InitStructure;
- /* Enable the TIM2 gloabal Interrupt */
- NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- /* TIM2 clock enable */
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
- /* Time base configuration */
- TIM_TimeBaseStructure.TIM_Period = 10 - 1; // 1 MHz down to 100 KHz
- TIM_TimeBaseStructure.TIM_Prescaler = 84 - 1;
- TIM_TimeBaseStructure.TIM_ClockDivision = 0;
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
- TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
- /* TIM IT enable */
- TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
- /* TIM2 enable counter */
- TIM_Cmd(TIM2, ENABLE);
- }
- /**
- * @brief Delay Function.
- * @param nCount:specifies the Delay time length.
- * @retval None
- */
- void Delay(__IO uint32_t nCount)
- {
- while(nCount--)
- {
- }
- }
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