Kinetis Software Development Kit中的主题 Re: K65 DSPI_EDMA driver

K65 DSPI_EDMA driver

ETCTim — Wed, 07 Sep 2016 12:50:22 GMT

Hello,

I am attempting to use the DMA SPI driver on a K65 with SDK 2.0.

I want to send 40K of data out the SPI to update a LCD screen.

I have successfully done this on a K70 with PE, and also a KL28 with SDK 2.0.

The fsl_dspi_edma driver seems to have an upper limit of 512 bytes per transfer as seen here...

/* this limits the amount of data we can transfer due to the linked channel.
* The max bytes is 511 if 8-bit/frame or 1022 if 16-bit/frame
*/
if (handle->bitsPerFrame > 8)
{
if (transfer->dataSize > 1022)
{
return kStatus_DSPI_OutOfRange;
}
}
else
{
if (transfer->dataSize > 511)
{
return kStatus_DSPI_OutOfRange;
}
}

It is unclear to me why there is a limit. How can I work around this?

Thanks.

Tim

Re: K65 DSPI_EDMA driver

xiangjun_rong — Thu, 08 Sep 2016 09:02:46 GMT

Hi,

As you know that the K66 has the same eDMA as K70, I do not know the background of the bytes limit, I think you can comment the code for byte count limit checking.

Hope it can help you.

Xiangjun Rong

Re: K65 DSPI_EDMA driver

vincentg_ — Thu, 22 Sep 2016 08:25:03 GMT

Hi,

any news about this? I stumbled upon the same lines of code working with the freedom k22 evalboard. Commenting the lines and sending bigger chunks will not work here.