eDMA with different source/destination data sizes

jvalenzuela — Wed, 20 Jan 2016 05:41:31 GMT

I have an application that requires a TDM8 stream to be transmitted using the I2S/SAI module. Said stream consists of eight channels of 16-bit audio. The receiver requires each TDM frame to be 32 bytes, or 256 bits, in length regardless of the actual data size. Using MSB-first transmission, each frame should begin with the MSB-LSB of the first channel, followed by 16 empty bits, then the MSB-LSB of the second channel, another 16 empty bits, and so on. To conserve memory, the source buffer within the Kinetis is an array of int16_t, so there is no padding between channels. Is it possible to configure the eDMA to read 16-bit data from the source, and write 32-bit data to the I2S TX FIFO?

Thank you,

Jason Valenzuela

Re: eDMA with different source/destination data sizes

EarlOrlando — Wed, 20 Jan 2016 18:27:09 GMT

Hello Jason,

Yes, the eDMA can do the padding automatically, the source data transfer size can be different than the destination data transfer size (please take a look into the DMA_TDCn_ATTR[SSIZE] and DMA_TDCn_ATTR[DSIZE] register fields).

Does this answer your question? If it doesn't please don't hesitate in contact me.

Best regards,

Earl.

topic Re: eDMA with different source/destination data sizes in Kinetis Microcontrollers

eDMA with different source/destination data sizes

Re: eDMA with different source/destination data sizes