Trying to build my own biquad I2S shield

[PegasYs]

Hello, I used the information given from the Audio System Design Tool and the SGTL5000 datasheet to try to make a biquad I2S shield, and using Eagle to design the board. My design came out like this and I ended up getting them produced by JLCPCB, but they're not working. I have a picture below of the schematic, only showing one of the SGTL5000s next to the wiring for the Teensy 4.0:

As far as I can tell I followed the exact recommended schematic to a T, as shown here: (Left off the headphone jacks cause I didn't really wanna use them):

Does anybody seem to know why mine isn't working? I uploaded a basic passthrough code and it works with my normal Teensy I2S shield. I also didn't know what it meant by "new designs" on the VDDD pin so I just left that off, it was really vague even in the text description on the datasheet.

I also realize it shows polarized caps but the ones I used were not polarized, I can assure that

 

[PegasYs]

I guess now looking at other schematics I can see that not hooking up the VDDD is where the problem lies. Guess I'm gonna have to get them rebuilt

 

[h4yn0nnym0u5e]

You may find you have other problems, too… I’d suggest you look at Paul’s known-working schematics on this page.

It’s not clear what you mean by a “biquad” audio shield (biquad is often used as an abbreviation for biquadratic filter). There are clues suggesting you’re wanting to make a 4-in 4-out shield, so I’m going with that. If I’m wrong, you may want to clarify matters…

• you’ve not connected the SGTL5000 control bus to the Teensy’s I2C; this is essential
• you’ve used the 20-pin version of the SGTL5000, which doesn’t have a configurable I2C address. This makes using two of them a pain, at best. Do yourself a favour and put 32-pin ones on, with their ADDR pins wired to give them different addresses
• fit I2C pull-ups
• you seem to be aiming to use a Teensy 4.0 - be aware that pin 32, needed for outputs 3 and 4, is actually a pad on the underside of the PCB. Your partial schematic makes it hard to guess your intentions…

As a rule of thumb, if you’re not sure what a pin does, you need to do more reading until you do understand it. Failing that, be sure at least to connect it to a test pad so you can modify the manufactured board. It’s also a good plan on a first board spin to make sure all signals are routed so you can cut the trace and re-wire it correctly, if needed. It’s rare to get anything other than the simplest board 100% right first time, but expensive and frustrating if you can’t even attempt to fix it

 

[PegasYs]

You may find you have other problems, too… I’d suggest you look at Paul’s known-working schematics on this page.

It’s not clear what you mean by a “biquad” audio shield (biquad is often used as an abbreviation for biquadratic filter). There are clues suggesting you’re wanting to make a 4-in 4-out shield, so I’m going with that. If I’m wrong, you may want to clarify matters…

• you’ve not connected the SGTL5000 control bus to the Teensy’s I2C; this is essential
• you’ve used the 20-pin version of the SGTL5000, which doesn’t have a configurable I2C address. This makes using two of them a pain, at best. Do yourself a favour and put 32-pin ones on, with their ADDR pins wired to give them different addresses
• fit I2C pull-ups
• you seem to be aiming to use a Teensy 4.0 - be aware that pin 32, needed for outputs 3 and 4, is actually a pad on the underside of the PCB. Your partial schematic makes it hard to guess your intentions…

As a rule of thumb, if you’re not sure what a pin does, you need to do more reading until you do understand it. Failing that, be sure at least to connect it to a test pad so you can modify the manufactured board. It’s also a good plan on a first board spin to make sure all signals are routed so you can cut the trace and re-wire it correctly, if needed. It’s rare to get anything other than the simplest board 100% right first time, but expensive and frustrating if you can’t even attempt to fix it

The bit about the pin 32 I do at least have covered, I just put a via on it to run a wire to the underside of the 4.0. I did this so I could do it with a 4.0 or 4.1 without changing the footprint. But obviously I have a lot of other problems haha. I've had a fair bit of luck on the past barely knowing what I've been working with and having it work out so far, knew my luck was gonna run out, I thought I had cleaned enough to make it work. Also is it not called biquad in the Audio System Design tool? I just used the name I saw there for the option of hooking up two Audio Shields. Regardless yeah it was probably a bad idea for me to jump the gun but live and learn, thanks for spending the time on helping me out!

 

[h4yn0nnym0u5e]

is it not called biquad in the Audio System Design tool? I just used the name I saw there for the option of hooking up two Audio Shields.

Nope. There’s an AudioFilterBiquad, described as a “Biquadratic cascaded filter, useful for all sorts of filtering. Up to 4 stages may be cascaded.” Then there’s AudioInputI2SQuad and AudioOutputI2SQuad which you’ll be using for your dual audio shield.

I just looked, and it appears JLCPCB have at best limited numbers of the QFN32 version of the SGTL5000 in stock. But the quoted lead times don’t look too bad, 9 or 10 days. Never had to contend with this so no idea if that’s realistic.

 

[PegasYs]

Nope. There’s an AudioFilterBiquad, described as a “Biquadratic cascaded filter, useful for all sorts of filtering. Up to 4 stages may be cascaded.” Then there’s AudioInputI2SQuad and AudioOutputI2SQuad which you’ll be using for your dual audio shield.

I just looked, and it appears JLCPCB have at best limited numbers of the QFN32 version of the SGTL5000 in stock. But the quoted lead times don’t look too bad, 9 or 10 days. Never had to contend with this so no idea if that’s realistic.

Ah yeah I got them confused, cause I was learning all about digital filters and got quad confused with biquad. I'm an EDM producer of more than 14 years and only now am I actually learning about the nitty gritty of the digital process of making music, but I guess to be fair the vast majority don't. Regardless, I will have to remake these and your help has made this a lot more of a possibility. Thank you.

 

[PaulStoffregen]

I hope you'll share photos and maybe even a video demo of the board when it's working?