Audio 8in and 8out Example from Paul with new chip

[hakon]

Hi
I’m working on a digital sound module/instrument that needs to have 8 audio inputs and 4 audio outputs and I’m not so experienced with digital commands and stuff so I’m asking for some help
Then I found a perfect example from Paul that has 8in and 8out with a CS42448 audio codex and PCM1808 ADC (https://hackaday.io/project/2984-tee...-for-teensy-4x),
but since I will be using JLCPCB to make the pcbs and put SMD components, I had to find another CODEX for the 6in and 8out because they don't have CS42448 in stock and its a little expensive.

PCM3168 seems to be perfect substitute but i am not sure how to connect the PCM1808 with that one. In the example from Paul the PCM1808 seems to be connecting to some input pins on the CS42448. But the PCM3168 does not seem to have them.

I will be using TDM to communicate with the Codex and ADC and from some research I’m still not sure if I can just connect the pins from both chips together into the teensy or if I have to do something else.
I'll put my schematics with this post, it's just a beginning where I have just copied the datasheets and the CS42448 example.

So my question is : how should I connect them together into the teensy for them to work both with TDM?
And all recommendations and links to answers or just all knowledge is appreciated

Links to datasheets of the chips:
https://www.ti.com/lit/ds/symlink/pc...t%252FPCM3168A
https://www.ti.com/lit/ds/symlink/pc...ct%252FPCM1808
https://pdf1.alldatasheet.com/datash...S/CS42448.html


Here is the schematics from Pauls example:

[TheHermit]

Hi Folks,
I'm currently designing a PCB which combines the CS42448 with differential op amp XYRGB outputs. So, I'm basically duplicating the OSH Park schematic and combining that with my own single ended TL082 op amp to differential circuits.
I see that the CAT811T IC has no inputs for control. Was this only provided for the future expansion of a second CS42448, as mentioned elsewhere? Q1: Can it be eliminated, with the !RST pin 3 on the CS42448 being held to either GND or @ 3.3V?

Also, I see that the CS42448 has differential outputs, which I'm currently creating with 2 stage op amps.
Q2: Does the Audio library support differential audio outputs from the CS42448? If so, then would it make more sense for me to switch my single ended to differential circuits to to single stage buffers on each differential output from the CS42448?
Thanks in advanced to whomever knows and shares the answers to these questions. Once the PCB is ordered, there's no correcting after the fact.

[Neal]

A1: In my experience, the CS42488 reset line startup requirements are a bit sensitive. You need the CAT811T to make sure no short glitches occur during the power up process. If a glitch occurs, the CS42488 doesn't reset with a simple !RST pin toggle. When I tried holding !RST low with a Teensy 4 output pin, it didn't work.

A2: It makes more sense to just use a differential stage output for the CS42488 similar to the ones outlines in the CS42488 data sheet. The Audio Library magnitudes will will be scaled by 2x if you have a differential output. That is simple to compensate for.

[TheHermit]

Thank you for the timely reply and helpful answers to my questions, Neal.

A1: In my experience, the CS42488 reset line startup requirements are a bit sensitive. You need the CAT811T to make sure no short glitches occur during the power up process. If a glitch occurs, the CS42488 doesn't reset with a simple !RST pin toggle. When I tried holding !RST low with a Teensy 4 output pin, it didn't work.

Understood. Good thing that I haven't already deleted it from the schematic and haven't wasted my $ on purchasing the CAT811T ICs.

A2: It makes more sense to just use a differential stage output for the CS42488 similar to the ones outlines in the CS42488 data sheet. The Audio Library magnitudes will will be scaled by 2x if you have a differential output. That is simple to compensate for.

Thank you for confirming that I don't need my current 2nd stage op amps to convert from single ended inputs to differential outputs. So, they will be reconfigured for the 1st stage buffers/offset correction on the - outputs. Lasers require DC coupling, without the output capacitors. So, offset correction is required.
2x gain is desirable. Laser projector standard X/Y (L/R audio) signal levels are +/- 10 V p-p.
IOW, life is good. Thank you for clearing the brain fog, in order for me to see that it is so.
Best Regards