Question
STM32F4 DMA and Timer Duty cycles
Posted on June 24, 2016 at 05:03
I am working on a personal project and keep running into a problem. The I am trying to use the DMA in an STM32F4 to control a strip of LEDs that rely on the duty cycle of an output signal.
I want to update the duty cycle of TIM5 at the end of each TIM5 period, I want to create a timer with a repeating duty cycle pattern (ie. 10% 20% 30% 10% 20% 30%...).
Is there something I am missing in my code in order to get that functionality?void ws2811LedStripHardwareInit(void){ TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; GPIO_InitTypeDef GPIO_InitStructure; DMA_InitTypeDef DMA_InitStructure; TIM5->CCR2 = 106; uint16_t prescalerValue; RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE); RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE); /* GPIOA Configuration: TIM5 Channel 1 as alternate function push-pull */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM5); // Stop timer TIM_Cmd(TIM5, DISABLE); /* Compute the prescaler value */ prescalerValue = (uint16_t) (SystemCoreClock / 2 / 84000000) - 1; /* Time base configuration */ TIM_TimeBaseStructure.TIM_Period = 104; // 800kHz TIM_TimeBaseStructure.TIM_Prescaler = prescalerValue; TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; TIM_TimeBaseInit(TIM5, &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(TIM5, &TIM_OCInitStructure); TIM_OC1PreloadConfig(TIM5, TIM_OCPreload_Enable); TIM_Cmd(TIM5, ENABLE); /* configure DMA */ /* DMA1 Channel Config */ DMA_Cmd(DMA1_Stream2, DISABLE); // disable DMA channel 6 DMA_DeInit(DMA1_Stream2); DMA_StructInit(&DMA_InitStructure); DMA_InitStructure.DMA_Channel = DMA_Channel_6; DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(TIM5->CCR1); DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)ledStripDMABuffer; DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral; DMA_InitStructure.DMA_BufferSize = WS2811_DMA_BUFFER_SIZE; DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word; DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word; DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable; DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull; DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single; DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single; DMA_Init(DMA1_Stream2, &DMA_InitStructure); DMA_ITConfig(DMA1_Stream2, DMA_IT_TC, ENABLE); DMA_ClearITPendingBit(DMA1_Stream2, DMA_IT_TCIF2); // clear DMA1 Channel 6 transfer complete flag NVIC_InitTypeDef NVIC_InitStructure; NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream2_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = NVIC_PRIORITY_BASE(NVIC_PRIO_WS2811_DMA); NVIC_InitStructure.NVIC_IRQChannelSubPriority = NVIC_PRIORITY_SUB(NVIC_PRIO_WS2811_DMA); NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); setStripColor(&hsv_white); ws2811UpdateStrip(); //sets LED strip to white, duty cycle of 68% //TIM5->CCR1 = 72;} #stm32f4-dma-timer