input capture _ DMA request

[nechi]

Posted on August 25, 2015 at 15:59

Hi,

Please i have to capture an input signal  and read it's frequency value with a DMA request but i can't find any ressources.I know the other solution with interreupt but i insist on this method with DMA, i need it.i did the configuration required but the buffer of destination shows always value=0 !here is my code:uint32_t TIM1CapturedValue_u32[2];void CaptureDMA(void){  DMA_DeInit(DMA1_Channel2);                                            //    Time1_ch1<-->DMA1_ch2              DMA_InitStructure.DMA_PeripheralBaseAddr = TIM_DMABase_CCR1;          //    Time1-->CCR1          DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)TIM1CapturedValue_u32[0];  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;  DMA_InitStructure.DMA_BufferSize =2;  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;                         DMA_InitStructure.DMA_Priority = DMA_Priority_High;  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;    DMA_Init(DMA1_Channel2, &DMA_InitStructure);    //Enable DMA1 channel2   DMA_Cmd(DMA1_Channel2, ENABLE);         TIM_TimeBaseStructure.TIM_Prescaler = 0; // Counter Clk = 72M   TIM_TimeBaseStructure.TIM_Period = 0XFFFF;   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;   TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);       TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;   TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;   TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;    TIM_ICInitStructure.TIM_ICFilter = 0x00;   TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;    TIM_ICInit(TIM1, &TIM_ICInitStructure);        /* Enable the TIMER CAPTURE DMA requests */ TIM_SelectCCDMA(TIM1, ENABLE); TIM_DMACmd(TIM1, TIM_DMA_CC1, ENABLE);           // TIM1 enable counter     TIM_Cmd(TIM1,ENABLE); }

[Tesla DeLorean]

Posted on August 25, 2015 at 16:33

You're using what processor?

u32 is NOT a HalfWord You want the Address of the Array, not the content

[nechi]

Posted on August 25, 2015 at 20:07

Hi Clive,

i'm using Timer 16 bits. Here is what i have understood: when the capture occurs, the DMA will be requested to transfer the value of the CCR1 and store it into the buffer so i need the content of the buffer i think . I can't find where is the mistake or if there is code missing  

[nechi]

Posted on August 25, 2015 at 20:08

ok i'll change it to u16. i'm using STM32F103

[Tesla DeLorean]

Posted on August 25, 2015 at 20:24

// Loading the DMA Address with random content, perhaps zero.

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)TIM1CapturedValue_u32[0];// Loading the DMA Address with the address of the first array elementDMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&TIM1CapturedValue_u16[0];

[nechi]

Posted on August 27, 2015 at 14:49

Thank you very much Clive 1 it works now.