Custom design on XU316 - no USB audio from I2S Topic is solved

[maxter]

I have a custom board based on the XU316, the board has 8 I2S inputs, 8 I2S output and ADAT RX.

My project is based on XTC tool 15.3.0 and the USB Audio software v8.1.0 .
I configured the I2S to be master (i.e. CODEC_MASTER=0) and I configured my ADC to be slave.
I see I2S data been driven by the ADC, so I assume that all the configuration on the acquisition side is correct, but I don't receive any audio from USB (I haven't tried the other way around, yet); before I dive into the I2S library, is there anything "obvious" I may have missed?
Do you have any advice on what start looking at to find out where the problem is?

These are my build flags:

Code: Select all

BUILD_FLAGS    = $(EXTRA_BUILD_FLAGS) -fcomment-asm -O3 -report \
    -lquadflash -lotp3\
    -g -fxscope \
    -DAUDIO_IO_TILE=0 \
    -DXUD_TILE=1 \
    -DUSB_TILE=tile[1] \
    -DI2S_CHANS_DAC=6 \
    -DI2S_CHANS_ADC=8 \
    -DXUA_ADAT_RX_EN=1 \
    -DMIN_FREQ=44100 \
    -DMAX_FREQ=192000 \
    -DADAT_TX_USE_SHARED_BUFF=1 -DXUA_QUAD_SPI_FLASH=1

The card is correctly detected by the OS (tried with both Mac and Linux) and when I change the sampling frequency on the Mac (in the Audio MIDI setup app)I see that the code passes through the AudioHwConfig() function and the PLL is being reconfigured.

[danielp]

I don't think there is anything obviously wrong with your configuration - I built an equivalent application using sw_usb_audio v8.1.0 for our XK-AUDIO-316-MC-AB board using your build flags, and I can correctly record eight channels from the ADCs.

Since you've already checked that you can see data driven by the ADC, I would start by debugging whether any samples are being received in the AudioHub_MainLoop function from the p_i2s_adc port array in lib_xua/lib_xua/src/core/audiohub/xua_audiohub.xc

[maxter]

I don't think there is anything obviously wrong with your configuration - I built an equivalent application using sw_usb_audio v8.1.0 for our XK-AUDIO-316-MC-AB board using your build flags, and I can correctly record eight channels from the ADCs.

Since you've already checked that you can see data driven by the ADC, I would start by debugging whether any samples are being received in the AudioHub_MainLoop function from the p_i2s_adc port array in lib_xua/lib_xua/src/core/audiohub/xua_audiohub.xc

I can see moving data in the samplesIn buffers (and 0s when I mute the ADC output), so definitely the I2S data arrives into the chip.
I tried to follow where those buffers are used, but without much luck.. any advice on how to proceed with debugging it?

[Ross]

This sounds like a custom board - make sure you have MCLK going into the xcore correctly.

For a two tile design it will need to go to both tiles (so two pins). One of the I2S to use and one for the USB sub-system to use to generate USB feedback and calculate packet sizes etc.

[maxter]

Thanks all for the assistance; in the end we found that everything was correct both hardware and firmware, and was "only" the test setup wrong, due to my lack of knowledge of the software I was meant to use (I am neither an audio engineer nor a Mac person).

We managed to have audio out from our board and back in a "nice" loop.

[Ross]

Well done :) Thanks for letting us know!