AnsweredAssumed Answered

STM32F4 I2S with DMA connected to Audio Codec, converting long to float

Question asked by Mig on Aug 19, 2013
Latest reply on Feb 12, 2015 by waclawek.jan
Hi,

I have the I2S running on STM32F4 with DMA and Interrupt connected to a 24 bit AD/DA codec, which works fine. I receive/transmit the 64 bit frame based on 4 DMA transfers between SPIx->DR and Memory.

Unfortunately the order of the Hi and Lo short (16 bit) is vice versa and I need to exchange the 16 Bit values to get a 32 bit Long, containing the 24 bit Audio in a correct order, to convert them via 'vcvt.s32.f32' and 'vcvt.f32.s32' to float and back.

Is there a possiblity to receive/transmit the 16 bit values in a correct order, without manually exchanging them? I'm not sure if the DMA FIFO could be an option, or how to configure this function correctly.

cheers
mig

Outcomes