TMS320F28388D: Data alignment issue using TX/RX DMA with SPIs

Hello Fabio,

Fabio Rastrello said:

I can succesfully send data from SPIB to SPIA, but there's no way to get data alignment. I supposed to have data aligment only with hardware configuration,

Can you clarify this question? I do not understand what you are looking for. 

Hi Gus,

the fact is that I'm sending with DMA a data buffer uint16_t spiBTxDataBuff[MCU2_TO_1_DATASIZE] from SPIB to SPIA and I collect it into uint16_t spiARxDataBuff[MCU2_TO_1_DATASIZE] with DMA, with MCU2_TO_1_DATASIZE = 60.

For example, In SysConfig, I configured for SPIB:

TXFFIL = 12, DMA_BURST_SIZE=4 and DMA_TRANSFER_SIZE=15

and for SPIA:

RXFFIL = 12, DMA_BURST_SIZE=12 and DMA_TRANSFER_SIZE=5

I manually update spiBTxDataBuff every 5ms and I can see in spiARxDataBuff data refresh but every time with a shifting: in this example, with this configuration parameters, every sending I can see 24 words shifting each time.

I also tried to follow Technical Reference Manual indication, but with similar shifting issues.

My question is: is there a parameter configuration for both sending and receiving SPI with DMA, in order to receive data with no shifting or should I suppose to align data at receiving side in some way?

I hope it is clearer.

Thanks,

Fabio

Fabio,

Fabio Rastrello said:

My question is: is there a parameter configuration for both sending and receiving SPI with DMA, in order to receive data with no shifting or should I suppose to align data at receiving side in some way?

I don't think any data manipulation will be needed.

In order for me to understand the problem better, can you provide a screen shot of the transmit and receive buffers? What is the SPI character size you are using? 

Thanks Gus,

here are the screenshots, but I apologize because I'm continuing developing and at the moment I changed buffer data from 60 to 48 words:

SPIB:

Running the code:

Considering xLastWakeTime (freeRTOS variabl), basically you can see the Tx buffer is not changing.

Instead, for SPIA:

During debugging:

In Rx buffer you can seee data shifting and with 48 words, now, sometimes data is aligned, but, of course, I would have it for any words number.

Just to be clearer:

uint16_t spiARxDataBuff[MCU2_TO_1_DATASIZE];              // Receive data buffer

uint16_t spiBTxDataBuff[MCU2_TO_1_DATASIZE];                // Send data buffer


// Addresses for SPI DMA channels
const void *dma1TxAddr = (const void *)spiBTxDataBuff;

const void *dma4RxAddr = (const void *)spiARxDataBuff;

I hope it is enough.

Thanks a lot,

Fabio

It worked, thanks a lot and best regards.

Fabio