how to wire an external DAC and to make it output some sound using an app made with sigma studio 4.7

Hello iravelo,

We have to make sure if the serial output port 2 is set up properly, so please attach your project.

If you are confident with your register settings, then probe the serial output port 2 and see the I2S signal and send us the scope pictures. I assume the DSP is the serial clock master.

Regarding the DAC, where is MCLK to the DAC coming from? Are you using DSP's CLKOUT pin? if you are, then well and good. No problem there.

what's the sampling rate? and how are you programming the DAC?

Are you sure about the DAC if it's up and running?

it must be really simple that we are missing here, so give us some info. we will be able to solve this.

iravelo said:

how to build a .dspproj app to handle that external DAC ?

Since this is not ADI's product, SS doesn't have a DLL for this. But you can create an XML file with the DAC's registers and program it from the master control port of the DSP. The below page shows how to do that.

Go to bottom of this page.

Regarding the wire connections,

If the DSP is sending out the MCLK to the DAC then,

DSP                                   DAC

CLKOUT      ------->          MCLK

BCLK_OUT2     ----->       BCLK/SCLK

LRCLK_OUT2   ----->       LRCLK/FRAME_SYNC

SDATA_OUT2 --------->    SDATA_IN/D_IN

GND<--------------------------->GND

Regards,

Harish

hi Harish, long time no see, best wishes !

let me send my current dspproj from another computer,

but in the meantime,

I can share that the external dac users who managed to make it work (on a raspberry pi) do says there is no MCLK to connect; the clock is "derived" from its DIN (48KHz being my adau's speed, as set by default).

I do not need SS to be able to reprogram or reconfigure the external DAC board, the latter is supposed to work as is (provided the jumpers are soldered as in the following image, and its SCK is grounded )

here is my dspproj 1467-01jan2026-a07Max-antal.dspproj

and here is how run the wires between the 2 boards, red one goes to +5V (on a third board), at the other side on the connector, the blue one goes to ground, and so on.. 

Hello iravelo,

Thank you, Best wishes to you too!

It seems you got confused with serial port channels.

You are sending 3 stereos out from the DSP. Here is the breakdown.

The channel 0-1 and channel 4-5 (SDATAIO) belong to serial output port 0 which are already connected to the on-board CODEC (DAC side), so you will get the analog out at jack J12 (OUT1) and J13 (OUT2) respectively.

Here is where the problem lies, you mentioned you use serial output port 2, but no channels were there in the schematic which belong to port 2, Rather you configured channel 46-47 which belong to serial output port 3 but stereo is not applicable on those slots even in port 3. So, the output from the core will be ignored, the serial port doesn't acknowledge it.

please have a look at the below table.

So, if you want to use stereo in output port 2 then channel 32-33 (primary) and ch 36-37 (SDATAIO) can be used.

if you want to use stereo in output port 3 then channel 40-41 (primary) and ch 44-45 (SDATAIO) can be used.

Your hardware connection seems correct; you have correctly connected the serial output port 2 pins to DAC, but you didn't select the correct channels in the schematic.

I have modified the outputs in your project, please give it a try.

1467-01jan2026-a07Max-antal_mod.dspproj

fantastic ! i gonna download the fixed project soon...

as expected, using the modded dspproj of yours, I hear things out of the external dac's 3.5mm socket, thanks a lot !!! you are great.

for the record, my adau board is revision B.

let me make sure I fully understand table#36:

- there are a total of 4 serials (out0..out3) and 48out channels

- not all 48channels are available as stereo pairs, these 8 can form stereo pairs : 0+1, 16+17, 32+33 & 40+41

- addtionnal 8 others could be used : 36+37, 44+45, and x+y, z+t

So if I want to use a 2nd external stereo dacs like my pcm1502 before, should I then connect that one to out3 pins of the adau board and use channels 40+41 in SS ?

and what if I wanted to wire a total of 4 external stereo DAC ?

cheers.