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我的PWM第一个脉冲有问题，周期不对，剩下的都正确，仿真的波形到是正确的。能否帮忙看看？
void timer2_pwm_ch2_init (void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
DMA_InitTypeDef DMA_InitStructure;
RCC_APB1PeriphClockCmd (RCC_APB1Periph_TIM2, ENABLE);
TIM_DeInit(TIM2);
/* Compute the prescaler value */
//PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 90 - 1; // 800kHz
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit (TIM2, &TIM_TimeBaseStructure);
/* PWM2 Mode configuration: Channel1 */
TIM_OCStructInit(&TIM_OCInitStructure);
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_OCInitStructure.TIM_OCIdleState=TIM_OCIdleState_Reset;
TIM_ARRPreloadConfig(TIM2, ENABLE);
TIM_OC2Init (TIM2, &TIM_OCInitStructure);
/* configure DMA */
/* DMA clock enable */
RCC_AHBPeriphClockCmd (RCC_AHBPeriph_DMA1, ENABLE);
/* DMA1 Channel7 Config for PWM2 by TIM2_CH2*/
DMA_DeInit (DMA1_Channel2);
DMA_StructInit(&DMA_InitStructure);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) &(TIM2->CCR2); // physical address of Timer 2 CCR2
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) WS2812B_OUTPUT_LED_PWM2_BUFFER; // this is the buffer memory
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; // data shifted from memory to peripheral
DMA_InitStructure.DMA_BufferSize = 42;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; // automatically increase buffer index
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; // stop DMA feed after buffer size is reached
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init (DMA1_Channel2, &DMA_InitStructure);
DMA_ClearFlag(DMA1_FLAG_TC2);
/* TIM2 DMA Request enable */
//TIM_DMACmd (TIM2, TIM_DMA_CC2, ENABLE);
TIM_DMACmd (TIM2, TIM_DMA_Update, ENABLE);
#if 1
WS2812B_send_led_pwm2(test_array, 1);
#endif
}
void WS2812B_send_led_pwm2 (uint8_t (*color)[3], uint16_t len)
{
uint8_t i;
uint16_t memaddr;
uint16_t buffersize;
buffersize = (len * 24)+1 ; // number of bytes needed is #LEDs * 24 bytes + 42 trailing bytes
memaddr = 0; // reset buffer memory index
uint8_t total=len;
while (len)
{
for (i = 0; i < 8; i++) // GREEN data
{
WS2812B_OUTPUT_LED_PWM2_BUFFER[memaddr] = ((color[0][1] << i) & 0x0080) ? TIMING_ONE : TIMING_ZERO;
memaddr++;
}
for (i = 0; i < 8; i++) // RED
{
WS2812B_OUTPUT_LED_PWM2_BUFFER[memaddr] = ((color[0][0] << i) & 0x0080) ? TIMING_ONE : TIMING_ZERO;
memaddr++;
}
for (i = 0; i < 8; i++) // BLUE
{
WS2812B_OUTPUT_LED_PWM2_BUFFER[memaddr] = ((color[0][2] << i) & 0x0080) ? TIMING_ONE : TIMING_ZERO;
memaddr++;
}
len--;
}
//===================================================================//
//bug：最后一个周期波形不知道为什么全是高电平，故增加一个波形
WS2812B_OUTPUT_LED_PWM2_BUFFER[memaddr] = ((color[0][2] << 8) & 0x0080) ? TIMING_ONE : TIMING_ZERO;
//===================================================================//
memaddr++;
while (memaddr < buffersize)
{
WS2812B_OUTPUT_LED_PWM2_BUFFER[memaddr] = 0;
memaddr++;
}
TIM_ClearFlag(TIM2,TIM_FLAG_Update );
TIM_SetCounter(TIM2, 0);
DMA_SetCurrDataCounter (DMA1_Channel2, buffersize); // load number of bytes to be transferred
TIM_Cmd (TIM2, ENABLE);
DMA_Cmd (DMA1_Channel2, ENABLE); // enable DMA channel 6
// enable Timer 3
while (!DMA_GetFlagStatus (DMA1_FLAG_TC2))
; // wait until transfer complete
TIM_Cmd (TIM2, DISABLE); // disable Timer 3
DMA_Cmd (DMA1_Channel2, DISABLE); // disable DMA channel 6
DMA_ClearFlag (DMA1_FLAG_TC2); // clear DMA1 Channel 6 transfer complete flag
}
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