Yummy AD/DA Cookie

Tiny audio PCBs

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Audio Cookies are tiny SMD audio circuits which can easily be used in bigger projects. The PCBs are designed in a castellated-holes style (aka half holes), which somehow reminds me on cookies.

This one is a square inch sized breakout board for the excellent AKM AK4556 audio codec.

I decided to split my ESP32 Guitar Shield project into smaller modules, which can be reused in other projects. This is the AD/DA part

AD/DA Cookie

This square-inch-sized PCB is a high quality audio codec board featuring an AKM AK4556 i.e. an analog to digital and digital to analog converter. 

  • I2S Interface (configurable)
  • Configuration is easily done with four pins, no complicated I2C interface 
  • 24 Bit, up to 216kHz 
  • Dynamic Range / Noise floor
    • ADC 103 dB
    • DAC 106 dB
  • Signal to Noise Ratio / THD+N
    • ADC 91 dB
    • DAC 90 dB

Please see the schematics in my GuitarShield Project to see the wiring. The configuration for an ESP32 can be seen in my yummyDSP audio library


KiCad schematic file

sch - 19.99 kB - 06/28/2019 at 09:38



KiCad Layout file

kicad_pcb - 104.23 kB - 06/28/2019 at 09:38


  • Schematics!!!

    GaryGru06/28/2019 at 10:01 0 comments

    I've uploaded the KiCad schematics and layout files. The connectors changed to a double row pin header half hole combination. The PCB is now breadboard friendly when assembled with pin headers but can still be soldered directly on a PCB as well.

  • yummyDSP ESP32 audio lib

    GaryGru06/05/2019 at 08:50 0 comments

    btw. I've uploaded the libray I'm yusing to GitHub

  • DevKit setup

    GaryGru06/05/2019 at 08:44 0 comments

    The codec is running fine in my ESP DevKit test setup. No problems so far even at 192 kHz! Input to output latency is only 2ms!

  • PCBs arrived

    GaryGru05/06/2019 at 08:05 0 comments

    Hooray, the OSHPark PCBs arrived. Took some weeks to Germany with free shipping. They are perfectly purple, solder mask and silk screen are looking really good. Knowing that OSHPark does not officially support castellated holes, at least one side is looking ok. The other side is not through-hole plated at all, although the design is fully symmetrical. Nevertheless, should be ok for a prototype (solder blobs to the rescue!)

  • Prototype PCB

    GaryGru04/14/2019 at 10:18 0 comments

    I decided to give OSHPark a try although they don't officially support castellated holes. So for now I'm waiting for the prototype PCB...

  • Gerber

    GaryGru04/10/2019 at 21:41 0 comments

    Today I found the time to finish the design and export the Gerbers in KiCad. 


    • Gerber export is done via File->Plot in PCBnew
    • Solder mask min width had to be set to 0.099 mm to allow 0.1 mm solder mask bridges between the codec pads (found in Setup->Pads to Mask Clearance)
    • Looks like castellated holes leads to extra charge due to special milling bits 

  • PCB layout

    GaryGru04/03/2019 at 21:47 0 comments

    Schematics and layout are done and yay it fits into 1 square inch! Gerber stuff and production files are next.

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GaryGru wrote 04/15/2020 at 21:41 point

Great @Juan! Have a look at my GuitarShield project to see an example of how to wire the Codec. I just shared my KiCad schematics. Feel free to contact me if you need more info. Cheers, Gary

  Are you sure? yes | no

Juan wrote 04/16/2020 at 16:46 point

Great, thanks

  Are you sure? yes | no

Riccardo Paolo Bestetti wrote 01/05/2020 at 15:23 point

Hi! I found this while researching alternatives to Bela (expensive) and freeDSP (expensive and afaik mostly out of production).

This project looks incredibly promising. In my opinion, to bring this forward, what is needed are more expansion boards. The ESP32 only has two I2S ports, but figure that with external framing and a proper HAL those could be multiplexed even for 4 in + 4 out 16 bits stereo channels at 48 kHz sampling rate.

Are you still working on this? Would you be open to collaboration?

  Are you sure? yes | no

GaryGru wrote 01/30/2020 at 08:42 point

Hi! Yes a proper HAL would be awesome. Also it should be no big problem to switch to TDM to get more channels. I also thought about expansion boards (Pots, mini TSR, CV stuff, ..) but I'm totally running out of time at the moment. So it would be great if you join the project. There is still a lot to do on the software and hardware side. Best, Gary

  Are you sure? yes | no

Juan wrote 03/06/2020 at 20:52 point

I am not having a lot of time, but happy to help too. Can you share how to connect to the DevKit?

  Are you sure? yes | no

Richard Hogben wrote 04/04/2019 at 15:23 point


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