RT1176 SAI1/2/3 for 8 channel per SAI TDM audio transfer

[SergD]

Hello,

Could you please help with understanding the limitations of SAI1/2/3 interfaces on RT1176 mcu?

In the Reference Manual I see the following:

"SAI-1 is used for multi-channel audio interface, which supports up to 8-channels audio
input or 8-channels audio output at 384 kHz/32-bit. SAI-2, SAI-3 and SAI-4 can be used
for stereo audio input and output up to 384 kHz/32-bit. Also SAI-3 is able to drive MQS
directly as a low-cost audio output."

Does that mean that I can't attach 8 channel TDM audio DAC to each SAI1 SAI2 and SAI3 to get 24 audio channel output?

I checked all the remaining Ref Manual and got no any signs that only SAI1 can work in TDM mode sending 8 channels of 24 or 32 bit samples  per frame.

And another question please - is there any additional documentation with detailed interrupts description?

For my application I need an interrupt that happens every sample sent through SAI1. It seems that WSIE will do just what I need, but it will be great to have more info.

Thanks!

[SergD]

Thank you!

Reading the RM I see the following

SAI-1 is used for multi-channel audio interface, which supports up to 8-channels audio
input or 8-channels audio output at 384 kHz/32-bit.

But later in the document I see more detailed info:

• Transmitter with independent bit clock and frame sync supporting 4 data lines
• Receiver with independent bit clock and frame sync supporting 4 data lines
• Each data line can support a maximum frame size of 32 words
• 8- to 32-bit word size
• Word size configured separately for the first word and remaining words in a frame
• Asynchronous 32 x 32-bit FIFO for each transmit and receive data line supporting

So it looks like I can send eight 32 bit words per frame on each data line.

So the question is - could you please confirm that I can attach three 8-channel DACs (to be precise - Texas Instruments PCM1690 DAC  https://www.ti.com/lit/ds/symlink/pcm1690.pdf ) - each to a single data line ?

Thank you!

[Omar_Anguiano]

No, as SAI1 is the only interface capable of supporting 8 channels. By connecting each device to a single data line you are limiting the device to only have 2 channels per device. 

Best regards,
Omar

[SergD]

could you please comment on this topic then - https://community.nxp.com/t5/i-MX-RT/How-many-TDM-channels-can-be-supported-in-RT1170-SAI1-TX-amp-RX...

[Omar_Anguiano]

Hello
I hope you are well.

Your understanding is correct, SAI2/3/4 are limited to 2 channels so a source of 8 channels is not possible; only on SAI1.
This app note might be helpful: Using Multi-Channel Feature of SAI (nxp.com)
Unfortunately, there is no additional documentation, the reference manual contains the SAI information.

Best regards,
Omar