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michaelmccartyeng
michaelmccartyeng
Associate III
February 17, 2014
Question

Does framing error make sense if you are tx'ing ? dma question

  • February 17, 2014
  • 7 replies
  • 902 views
Posted on February 17, 2014 at 21:48

Hello All, hope you are doing well Clive.

 I dont know if i've always had this issue but I always get a FE int in my DMA1_Stream6, but I only use that dma for transmitting. From what I understand a framing error would be on the receiving end of things right ?

Thanks !
    This topic has been closed for replies.

    7 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    February 17, 2014
    Posted on February 17, 2014 at 22:10

    In the context of a USART perhaps, not so sure what it means with DMA, where there are two sides to the transaction (Read / Write), an uninformed guess might be that it relates to the memory alignment of one of the transfers.

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    Tesla DeLorean
    Tesla DeLorean
    Guru
    February 17, 2014
    Posted on February 17, 2014 at 22:20

    FIFO Error != Framing Error

    0690X00000605XiQAI.png
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    michaelmccartyeng
    michaelmccartyengAuthor
    Associate III
    February 17, 2014
    Posted on February 17, 2014 at 22:34

    Well that makes sense, no wonder I could not make heads or tails of it. I keep looking at ''framing error''.

    Thanks Clive, now I know where to start looking. I think what you wrote means something along the lines of I need to have a divisible by X number of bytes to transmit. I'm already padding out some bytes to make a CRC so it must be divisible by 4. I'll investigate more in the fifo area ! This is the code in case your curious. 

    DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART2->DR); 
// usart2 data register
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&FrameBuffer[mPacketTransferIter*MAX_PACKET_SIZE];
mPacketTransferIter++; 
// this will make our array point to the next chunk
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
// if we need to transfer more then only send up to max packet size
if
(mBytesLeftToTransfer > MAX_PACKET_SIZE)
{ 
DMA_InitStructure.DMA_BufferSize = MAX_PACKET_SIZE;
mBytesLeftToTransfer = (mBytesLeftToTransfer - MAX_PACKET_SIZE);
}
else
{ 
// else send whats left ! 
DMA_InitStructure.DMA_BufferSize = mBytesLeftToTransfer;
mBytesLeftToTransfer = DONE_BYTES; 
// set this so we know its the end
}
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
//DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
//DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

    michaelmccartyeng
    michaelmccartyengAuthor
    Associate III
    February 17, 2014
    Posted on February 17, 2014 at 22:35

    Well that makes sense, no wonder I could not make heads or tails of it. I keep looking at ''framing error''.

    Thanks Clive, now I know where to start looking. I think what you wrote means something along the lines of I need to have a divisible by X number of bytes to transmit. I'm already padding out some bytes to make a CRC so it must be divisible by 4. I'll investigate more in the fifo area ! This is the code in case your curious. 

    DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART2->DR); 
// usart2 data register
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&FrameBuffer[mPacketTransferIter*MAX_PACKET_SIZE];
mPacketTransferIter++; 
// this will make our array point to the next chunk
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
// if we need to transfer more then only send up to max packet size
if
(mBytesLeftToTransfer > MAX_PACKET_SIZE)
{ 
DMA_InitStructure.DMA_BufferSize = MAX_PACKET_SIZE;
mBytesLeftToTransfer = (mBytesLeftToTransfer - MAX_PACKET_SIZE);
}
else
{ 
// else send whats left ! 
DMA_InitStructure.DMA_BufferSize = mBytesLeftToTransfer;
mBytesLeftToTransfer = DONE_BYTES; 
// set this so we know its the end
}
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
//DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
//DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

    michaelmccartyeng
    michaelmccartyengAuthor
    Associate III
    February 17, 2014
    Posted on February 18, 2014 at 00:15

    I've tried several ''fifo'' modes and settings, I always get the FE along with TC. I think this is because the last bytes we transfer are not on the 32 byte boundry ?

    I'm going to refactor my code to byte stuff till its %32 == 0 (instead of %4). Will take me a while but maybe it will help the DMA work :\

    michaelmccartyeng
    michaelmccartyengAuthor
    Associate III
    February 18, 2014
    Posted on February 18, 2014 at 03:27

    I still get a FE no matter what I do. I've made sure the data I'm sending out is divisible by 32 thinking that would resolve any issues the DMA may have. There is not one example using DMA with USART for TX.

    Closest I can find does this, which makes no sense to me. Why disable ? 

    00217 DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable ;
00218 DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull ;
00219 DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single ;
00220 DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;

    Does anyone know what my settings should be if my data is divisible by I'm currently just sending out a large chunk of around 3k bytes thats divisible by I always get a FE set with a TC. The bytes left to transfer is empty. Maybe its some one based/zero based issue. I tried to update my perph library i'm running V1.0.0 and the current is V1.3.0. I thought Maybe that would fix things. But that has other issues that i'll put in a new thread.
    michaelmccartyeng
    michaelmccartyengAuthor
    Associate III
    February 19, 2014
    Posted on February 19, 2014 at 01:27

    I reduced my dmatx function to its pure essence and I send out a fixed packet of 384 bytes and I still get a TE interrupt. I get it when ntdr is 0. Its weird when I hit the first bp on the isr TC is not set but shortly after it is. So its hard to tell if TE is set then TC just after or if they are always getting set at the same time. 

    void restartCommDMATX(u8* FrameBuffer,int start, int size)
{
DMA_InitTypeDef DMA_InitStructure; 
DMA_DeInit(DMA1_Stream6);
DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART2->DR); // usart2 data register
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&FrameBuffer[start];
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStructure.DMA_BufferSize = size;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
// FIFO 
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
// init the dma
DMA_Init(DMA1_Stream6, &DMA_InitStructure);
USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE);
// setup transfer complete int, and error init 
DMA_ITConfig(DMA1_Stream6, DMA_IT_TC, ENABLE);
DMA_ITConfig(DMA1_Stream6, DMA_IT_FE, ENABLE);
DMA_ITConfig(DMA1_Stream6, DMA_IT_TE, ENABLE);
// start the dma transfer, it will execute now
DMA_Cmd(DMA1_Stream6, ENABLE);
}

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