XCore Exchange

Hello,

I´m trying to get an I2S signal (MCKL, BCKL, LRCKL, DATAIN/OUT) out of the board, without the line plugs, directly over this 4 lines to send I2s messages to another board what only can handle i2s via PCM.
So I used the I2s loopback demo and tested it with line in and line out. That works fine, I can hear the 1 khz sine I deliverd to the board.
Now Im trying to get this over the 4 mentioned pins. I use MCKL for MCKL, SCLK for BCLK, LRCKL for LRCLK and for DATAIN -> xADC1 and DATAOUT -> xDAC1.
I dont realy know if it´s the right way, but the Audioprecicion shows me a small drivt in the clock around 48khz but it´s slipping around +- 100 Hz or a little more. Also I don´t geht the 1khz sine from input to output, so anything is wrong in my config.
Same with the SPDIF to I2s ASRC demo. With a headphone attached to the line out dac I can hear the sine very nice in all 4 samplerates, but when I try to get the sine out over the 4 i2s lines as mentioned above the samplerate is slipping a bit +-100 Hz and no output.
Do you have a small hint for me?

Best regards
Contax9

Hi you dont write who is master who slave ... Too what code you use, but if usb mc audio, this is independent input and output I2S. Copy or bypass is possible only in PC or with rewrite your code... that you dont show here

Hello mmar,

thanks for your replie, its the offical xmos i2s lib loopback demo, xmos is master in both ways https://github.com/xmos/lib_i2s/tree/de ... pback_demo
Also the offical xmos src lib demo "ASRC_SPDIF_TO_DAC", xmos is master in both ways,too :https://github.com/xmos/lib_src/tree/de ... DIF_TO_DAC.

Maybe you dont explain what you do and what board used. X200 mc AB dont have I2S ext .

I use the XK-AUDIO-216-MC-AB.
Okay that's sad to hear.
My plan is to get a signal with spdif into the board and get I2s as PCM out of the board. So I thought I could grab the I2s signal at the SDOUT1(Middlerow of the DAC Block) and the clocks at the MCLK,SCLK and LRCLK Pins.

In my experience using jumper wires from I2S lines is OK for maybe prototype and quick test, but as you are finding not very reliable. You might try adding some source resistance to the line?

RitchRock wrote: ↑Tue Mar 08, 2022 12:00 am In my experience using jumper wires from I2S lines is OK for maybe prototype and quick test, but as you are finding not very reliable. You might try adding some source resistance to the line?

I use BNC to Molex to connect the board with the AudioPrecision. I never had any issue using the cables with other boards and I2s. But if it´s like mmar said that there is no connection on the board to get I2s out of the board without using the DAC Lineouts, than the board itself isn´t very interessting for me.

Are you currently using J7 to get the I2S signals? Removing the jumpers should isolate the lines from the DAC I2S pins. See attached snip from the hardware manual.

RitchRock wrote: ↑Wed Mar 09, 2022 2:57 am Are you currently using J7 to get the I2S signals? Removing the jumpers should isolate the lines from the DAC I2S pins. See attached snip from the hardware manual.

Yes, I use pin 2 on J7 for DATA Out and pin 2 on J8 for DATA In, but thanks, it wasn´t really clear for me if that are the right pins, especially because mmar said there is no ext. I2S on this board....
For the I2S loopback it works now, I can get I2S from the AP PSIA into the board and get analog out and vice versa. It was just a little master slave clock problem. The MCLK connection was unnecessary, even in slave mode. So dropping it gave me a stable clock.

Yes jumpers is only for DATA, other wires you need solder to board and you can damage it. But if all is ok your idea may work, but for byposs SPDIF IN to I2S out you need rewrite code...