Updated CS42448 PCB for Teensy 4.x

A project log for Teensy Audio Library

CD quality sound processing, integrated with Arduino sketches

Paul StoffregenPaul Stoffregen 12/30/2020 at 12:3216 Comments

I've created a new version of the CS42448 TDM test board.  It's updated for Teensy 4.x pinout.

An unpleasant discovery from the prior version was how hot the CS42448 chip runs.  On this 2nd version, I've added copper underneath the chip and on the bottom layer to try to dissipate some of the heat.

I also added a PCM1808 ADC, so all 8 inputs can be used instead of only 6.

This version also adds a 14 pin header in the center, so it can be easily connected to the Dual Interleaved CS42448 board... which is still a work-in-progress.

My hope is to eventually be able to connect 2 of these boards to each TDM port, so all 16 inputs and all 16 outputs can be used.  With 2 TDM ports, that should make 32 simultaneous audio input & output possible.....


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Gruftgrabbler wrote 02/16/2021 at 17:12 point

Hey Paul. Thanks for pulling this again and supporting the community. Just wanted to ask if there is a BOM for this PCB?

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glenn wrote 02/11/2021 at 02:37 point

Hi Paul, is this board going to be available for ordering from OSH Park? I see that the previous version ( is there.

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Paul Stoffregen wrote 02/11/2021 at 04:14 point

Yes, it already is.  Here's the link.

So far I've built 1 board.  I personally tested the 8 outputs, then I sent it to someone in Germany who has confirmed all 8 inputs also work.

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glenn wrote 02/22/2021 at 20:39 point

Is there a parts list for this version of the board?

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Paul Stoffregen wrote 02/22/2021 at 20:49 point

Nope, I haven't had time recently to do any more work on this, so there's no parts list specific to this PCB.  I haven't even had time to build another board (sent the 1st one to Frank in Germany), so I don't even have one running here.

But the electrical design is nearly identical older version, except for the PCM1808 and nearby parts, and maybe a few common resistors.  You can also just leave off the PCM1808 and it will work just like the old one did, with 6 inputs instead of all 8.

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glenn wrote 02/24/2021 at 04:52 point

I went through and updated the parts list to match this board. I didn't make any changes to this list, although I would recommend changing the X5R resistors in the audio path to X7R to reduce low-frequency THD.

 1   CS42448, Codec Chip            598-1033-ND
 1   PCM1808, ADC Chip              2156-PCM1808PWG4-BB-ND
 1   CAT811T, Reset Chip            CAT811TTBI-GT3OSCT-ND
 8   Connector, audio               CP1-3525N-ND
 1   Resistor, 0 ohm, 603           311-0.0GRCT-ND
 8   Resistor, 150 ohm, 603         311-150HRCT-ND
 8   Resistor, 560 ohm, 603         RMCF0603FT560RCT-ND
 2   Resistor, 2.2K ohm, 603        311-2.20KHRCT-ND
 8   Resistor, 10K ohm, 603         311-10.0KHRCT-ND
10   Resistor, 100K ohm, 603        311-100KHRCT-ND
16   Capacitor, 2.7nF, NP0, 805     445-7508-1-ND
 4   Capacitor, 10nF, X7R, 603      490-1512-1-ND
10   Capacitor, 0.1uF, X7R, 603     490-1524-1-ND
14   Capacitor, 4.7uF, X5R, 805     1276-6463-1-ND
10   Capacitor, 10uF, X5R, 805      399-4925-1-ND
 1   Capacitor, 22uF, X5R, 805      490-1719-1-ND
 1   Capacitor, 100uF, X6T, 1206    490-10525-1-ND
 1   Inductor, Ferrite Bead, 805    490-1054-1-ND
 1   Circuit Board        
 1   Teensy 4.0           
 2   Socket, 14x1         
 2   Header, 14x1         
 1   Heatsink                       (optional: CS42448 runs hot)

I also created a schematic in KiCad, although there doesn't seem to be a way to attach PDFs here. Paul, can I send it to you so that you can make it available for others?

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Paul Stoffregen wrote 02/24/2021 at 10:38 point

Can you upload the schematic and other files to github?  Or a page here on  Or any other site with a permalink (pretty much anything except Facebook).  Then I'll add links here and on the OSH Park page.

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glenn wrote 02/26/2021 at 17:44 point

I put my KiCad schematic files on github, as well as a PDF version of the schematic and a BOM (including Digikey, Mouser, and PJRC part numbers) in .csv format. If anyone finds any discrepancies between the PCB and schematic, let me know

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David wrote 02/06/2021 at 20:56 point

nice thx a lot :) is Multichannel usb audio possible by any chance ? That would be sooo dope

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Paul Stoffregen wrote 02/07/2021 at 00:41 point

It certainly is possible on Teensy 4.0 & 4.1 with 480 Mbit/sec USB speed, where "possible" means a deep dive into USB descriptors and buffers and low-level code.  There's a thread on the forum where a few people have tried.  So far none have reported success or shared any useful code.

Where "possible" means already implemented in the libraries and reasonably well documented in the graphical design tool, and actually tested to work with some combination or Mac, Windows & Linux, well... that may be a while.  Right now many things are much higher priority, including better documentation of the many features already implemented.

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David wrote 02/07/2021 at 09:31 point

thank you for the quick reply. Sadly I’m not dev enough to solve that I think but I will keep an eye on the forum. Thanks so much for your work and the time to answer. I’m a designer, if that  can be of any help (ux, icons...) let me know. 🙏

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Arev wrote 01/17/2021 at 02:26 point

Dear Paul, do you plan to share the schematics for the board? I'm a little confused regarding the TDM communication / connection. All the best!

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Paul Stoffregen wrote 02/07/2021 at 19:47 point

There is no schematic.  I just put the parts right into the layout and click their pins to form the netlist.

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Arev wrote 02/07/2021 at 20:01 point

no worries, I guess it was just too late to think clearly at the time ;) 

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Christian vdF wrote 01/05/2021 at 11:08 point

You have done so much for the community...really thak you sir!!! :) . Ive  been doing some audio proyects with my teensy but this is a must!

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