Associate II

Question

STM32L4 DMA read write multiple blocks problem

Forum|Forum|9 years ago
August 3, 2017
12 replies
3077 views

Posted on August 03, 2017 at 12:36

I have a problem with DMA mode reading multiple blocks.

To simplify a problem i took an example from the

STM32Cube_FW_

L4_V1.8.0\Projects\STM32L476G_

EVAL\Applications\FatFs\FatFs_

uSD\ archive.

BSP_SD_ReadBlocks_DMA

is used.

Read blocks not worked good, it started to work after i separated rx and tx and added Init and Deinitto DMA each time that i use that channel.

The problem is witha write now. I can write only blocks that are less then 1k. from 1k to 4096 sometimes it can write and sometimes

f_writereturn 0x

It always fails to write blocks bigger then 4096, bsp_write_blocks always fails with MSD_ERROR .

The problem only in DMA mode, polling mode works great.

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Tesla DeLorean

Guru

Posted on August 03, 2017 at 14:18

With write using SDIO+DMA, one problem is that the DMA completes long before the SDIO FIFO clears, so using the DMA TC as a completion indicator is problematic. So after confirming DMA TC signals, you then need to watch the FIFO depth zero out.

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Yaroslav KirillovAuthor

Associate II

Posted on August 03, 2017 at 15:36

Thank you for your fast reply.

Do you know which function should we use to check the FIFO empty state?

Tesla DeLorean

Guru

Posted on August 03, 2017 at 17:11

It will be the SDMMC_FIFOCNT register, you'll need to grep the library source to see how that is exposed/wrapped.

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Poonam Deoghare

Associate II

Posted on March 23, 2018 at 13:01

Hi,

Even I am facing problem when trying to read/write in DMA mode.

Rewritten call back functions in my c file and checking the card status also.

I am working on f4 disco EVAL.

Kirillov.Yaroslav

please let me know if you got read/write DMA working with one and multiple blocks.

Thanks,

Poonam

Tesla DeLorean

Guru

Posted on March 23, 2018 at 13:34

He's using an L4, not an F4

STM32Cube_FW_F4_V1.19.0\Projects\STM32446E_EVAL\Applications\FatFs\FatFs_uSD_RTOS\Src\sd_diskio_dma.c

SDIO+DMA is workable on a number of F4 platforms

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Poonam Deoghare

Associate II

Posted on March 26, 2018 at 09:09

Hi Clive,

You are right that SDIO+DMA is workable on a number of F4 platforms but I have following issue.

When I read/write single block in DMA mode without file system , it is working fine.

But When I am writing/ reading multiple blocks (1000) blocks in loop , I am not sure what exactly is happening.

I am writing and trying to read same data in buffer. That buffer (Rx), when I print, it is empty.

while(i++ < 1000)

{

txDone = 1;

//printf(' Write_addr is 0x%x \n' ,addr);

HAL_SD_WriteBlocks_DMA(&hsd, Tx, addr, 1);

while(txDone == 0 ){} //it will be set in call back function

while(HAL_SD_GetCardState(&hsd) != HAL_SD_CARD_TRANSFER){}

addr += 0x200;

}

while(i++ < 1000)

{

rxDone = 1;

HAL_SD_ReadBlocks_DMA(&hsd, Rx, read_addr, 1);

while(rxDone == 0 ){} // it will be set in callback function

while(HAL_SD_GetCardState(&hsd) != HAL_SD_CARD_TRANSFER){}

read_addr += 0x200;

printf('RX is %s \n', Rx);

}

Nikolay Brinken

Associate III

Posted on March 29, 2018 at 11:22

After invoked

__SDMMC_DMA_DISABLE(SDMMC1);

I test is SD busy

while(!LL_GPIO_IsInputPinSet(GPIOC, LL_GPIO_PIN_8)){};

where port C pin 8 - SD data 0 pin

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