DMA won't get enabled

[joecarlhr]

Posted on March 29, 2014 at 17:53

Hello stmGuys. I'm having a problem configuring my DMA. I've tried everything I can imagine and it still doesn't work. I want the DMA to transfer data from a memory array to the GPIOD->ODR register. Here is my DMA_Init function:

void

Init_DMA() { RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE); RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); DMA_InitTypeDef DMA_InitStructure; TIM_TimeBaseInitTypeDef timerInitStructure; timerInitStructure.TIM_Prescaler = 0; timerInitStructure.TIM_CounterMode = TIM_CounterMode_Down; timerInitStructure.TIM_Period = 1; timerInitStructure.TIM_ClockDivision = TIM_CKD_DIV1; timerInitStructure.TIM_RepetitionCounter = 0; TIM_TimeBaseInit(TIM2, &timerInitStructure); TIM_DMACmd(TIM2,TIM_DMA_Update,ENABLE); //This is connected to DMA1_Stream1 Channel_3 TIM_Cmd(TIM2, ENABLE); DMA_DeInit(DMA1_Stream1); while (DMA_GetCmdStatus(DMA1_Stream1)); //Wait until its ready to be configured DMA_InitStructure.DMA_Channel = DMA_Channel_3; DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) &GPIOD->ODR; DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t) &v_memory[0]; DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral ; DMA_InitStructure.DMA_BufferSize = 160; DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte; //Tried all possible combinations sizes DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; // DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable; // DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOStatus_HalfFull; // DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single; //I've tried all possible combinations with these params DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single ; // DMA_Init(DMA1_Stream1, &DMA_InitStructure); DMA_Cmd(DMA1_Stream1, ENABLE); } v_memory is defined as: uint8_t v_memory[160]; The GPIOD is well configured as output. In my main loop I'm continously checking DMA1_Stream1 status and I've discovered its always disabled. Even if I enable it just before checking. If I don't configure Timer2 as the DMA Request then the DMA keeps enabled but it doesent transfer any data... I want this transfer to be done every time the timer reaches 0 value. I'm refilling this timer in other function so it's not the problem. I really can't see what I'm missing. Anyone there able to bring light here? Thanks in advance.

[Tesla DeLorean]

Posted on March 29, 2014 at 17:57

The AHB is not on APB1, I think you need to use DMA2 for such transactions.

https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Data%20transfer%20from%20GPIO%20port%20to%20RAM%20buffer%20using%20DMA%20upon%20receiving%20a%20trigger%20signal%20on%20the%20timer%20capture%2...

[joecarlhr]

Posted on March 29, 2014 at 18:17

Thanks for your answer clive1. I already tried DMA2 with TIM1. Sorry for not mentioning it. It didn't work either, actually DMA2's clock is AHB1 too.

Is there anything else I could have missed?

[Tesla DeLorean]

Posted on March 29, 2014 at 18:35

Both DMA1 and DMA2 are on AHB, however DMA1 works with APB1 peripherals, and DMA2 works with APB2 peripherals.

The Period of One is a bit on the low side, not sure how that's remotely sustainable. Does the DMA flags some error or under/overflow condition? I'm only going to touch complete exemplars.

[joecarlhr]

Posted on March 29, 2014 at 19:25

Well you are right. I reconfigured it again to use DMA2_Stream5 Channel_6 with TIM1 now it  keeps enabled and all error flags are set to 0. I changed Timer period to 10. But It's still transfering nothing to GPIOD->ODR.

Is this normal? Isn't there any extra configuration I'm missing? EDIT: Sorry, all I said in this last post was not ture, I just forgot to enable TIM1 clock and thats why the DMA was keeping enabled.  I enabled TIM1's clock and the DMA gets disabled again and actually the FIFO error flag is set. Even with FIFO mode disabled....

[Tesla DeLorean]

Posted on March 29, 2014 at 19:46

Ok, this is the example I was looking for earlier, where I output via the GPIO using an internal clock. I don't have a scope or bench set up to test things right now, but this was tested with a scope to prove GPIO output.

https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/DMA%20MemoryToMemory%20using%20Timer%20for%20delivery%20rate&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD065...

Observe how the example is formed and presented as a stand-alone demonstration.

[joecarlhr]

Posted on March 30, 2014 at 12:39

Thanks so much clive1 I got some output on GPIOD->ODR now. It's a bit complicated to understand the way this DMA works...