My Code example:

/* Open SPI as master (default) */
SPI_Params_init(&spiParams);

spiParams.frameFormat = SPI_POL0_PHA1;
spiParams.bitRate     = 4000000;

masterSpi = SPI_open(CONFIG_SPI_0, &spiParams);

// [...]

transaction.count = 4;
transaction.txBuf = (void *) masterTxBuffer;
transaction.rxBuf = (void *) masterRxBuffer;

/* Perform SPI transfer */
transferOK = SPI_transfer(masterSpi, &transaction);

// [...]

SPI_close(masterSpi);

Hi Joerg,

Which version of the SimpleLink SDK are you using?

Cheers,

Marie H

Hi Marie,

I am using:

SimpleLink CC13x2_26x2 SDK 5.20.00.52

Cheers,
Joerg

Hi Joerg,

Would that thread be of help to you? https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/1096650/launchxl-cc1310-spi-transmit-and-receive-count-affects-the-waveform-of-cs

Regards,

Arthur

--

EDIT: This works only when clk phase is 1 (SPI_POLx_PHA1). Hence, doesn't resolve my issue. See testing results below.

--

Yes, I can confirm that I have exactly the same behaviour. And setting Min DMA Transfer size resolves my issue.

I leave some notes here in this thread for others (and for my future me).

Min DMA Transfer Size is set as default to 10 Bytes, hence this gives me:

9 Bytes

then for 10 Bytes:

In SysCfg Editor: setting Min DMA Transfer Size to desired size (here 2 Bytes), gives me:

And this is exactly what I need.

Thanks

Joerg

Min DMA Transfer Size can be set via SysCfg Editor, hence configurable at SysCfg-Built-Time. Is it also possible to reconfigure this during run-time?

Hi Joerg,

You could probably do so, but that would involve disabling SysConfig for driver configuration. Here is a non-tested procedure:

1. First, copy the previously generated ti_drivers_config.c and ti_drivers_config.h to the root (or another folder) of your project.
2. Disable SysConfig driver generation by unchecking ti_drivers_config.c/.h in SysConfig.
   
3. From there, remove the const qualifier of the spiCC26X2DMAHWAttrs structure, present in ti_radio_config.c.
4. Added the following lines in spimaster.c, to get access to the HWAttrs structure:
   

   #include <ti/drivers/spi/SPICC26X2DMA.h>
   
   extern SPICC26X2DMA_HWAttrs spiCC26X2DMAHWAttrs;

5. You can now modify the minDmaTransferSize field, prior to SPI_open.
   

   spiCC26X2DMAHWAttrs.minDmaTransferSize = 15; //Whatever value you need.
   masterSpi = SPI_open(CONFIG_SPI_MASTER, &spiParams);

Regards,

Arthur

Hi,

Thanks for the manual ti_drivers_config.c and ti_drivers_config.h approach.

Actually, setting minDMATransferSize doesn't work with every spi frame format.

It only works when phase is 1. But I need polarity 0 and phase 0.

Here are my testing results:

I haven't rad the full thread so it could be that it has already been suggested. In this case, why not use the SPI driver in 3 wire mode and set CSn with a DIO controlled from outside the driver? 

Yes, I am using now 3-Wire mode and drive the CSn manually.

I still consider this as an workaround and think the DMA mode is not working properly when using CPHA=0.