palmerr

Any USB audio functions are not related to the hardware. This hardware would be compatible with any transport protocols up to 32 x 32 channels. I'd suggest that you ask the question under a separate topic. Another option would be to use my...

Almost no difference between K and M - I simply had the wrong 1.8V regulator specified on L. L & M have the extra buffers on MCLK and WCLK and an extra pin on the Expansion header to more easily enable 32x32 mode. All three revisions work...

Hi All, Two updates. 2-stage DAC Biquad filters added to repo - code and arguments are based on Teensy Audio filter_biquad.h More boards are available on Tindie - with the WCLK and BCLK buffers + an extended expansion header for the...

Yes, that looks correct. BTW, I'm working on a stackable 4 channel mic-line preamp board. Very low noise, individually switchable phantom power, individually switchable -30dB pad (for pro-line inputs) and 20dB gain to bring the level up to where...

I've rewritten HPF to accept any cut-off frequency up to 5kHz. 0 still sets the filter off. Verbose( ) now controls HPF( ) diagnostic printing. Enjoy!

OK, a little less efficient than doing a full 32-bit transfer, but workable enough! Might as well set 32-bit mode and be done with it. I'll get onto the control code over Easter. It shouldn't be too hard - just a couple of changes to the code...

A code update overnight fixes the gain and HPF issues. Use HPF( ) instead of setHPF( )

Yes, I've been using the platypus logo on musical instruments and technology for more than 15 years. I thought I'd bring it across!

The new HPF( ) code has been updated to fix a definition error.

Another option is to add a pin to the Expansion header. It can be fly-leaded to 32 on the main PCB and patched where needed on slaves. It's the only extra signal now that each board has BCLK/LRCLK buffers. The OUT1A / OUT1C patch is already...

Jonathan, I have uploaded new code for the HPF which has corner frequencies of 0Hz (off), 10, 20 & 50Hz. It uses the programmable coefficients on Reg Page 1 instead of the default set, The new function is HPF(freq, chan, codec) Thanks for the...

I've updated the hardware repo with the full Rev K schematics. The only difference is the added BCLK/LRCLK buffers and removal of the series resistors for DI/DO (as above). I will add the PCBA files after the initial run of boards has been tested.

Jonathan, I'm updating the commissioning notes for 32x32 mode for the next gen board with MCLK and LRCLK buffers on board: Is this the correct text for 32x32 mode? I'm still not quite clear on the correct SAI1 mappings.

I just found this reference - it might help... TI SCAA088 Generating Low Phase-Noise Clocks from low frequency word clock

I'd agree, clock sync is a whole other issue. I've subscribed to the thread you referenced, if the discussion ever picks up again. Phase-locked loops could regenerate BCLK and MCLK from LRCLK, though getting the phase shift small enough could be...

@JayShoe Basically, whatever Paul's licence on his Teensy products is, that's what mine will be. Syncing with an external clock isn't on the cards for Teensy, AFAIK. It's a whole other level of complexity, probably better to use the Teensy to...

24 bit is not formally supported, but there are a number of forks for higher bit count. Of course you reduce the number of supported channels that will fit into a 256bit slot when you increase the bit depth! For live sound, 16 bits isn't much...

Not derailing at all - the whole reason we build the hardware and software is for people to use it in interesting ways. Good to see that there's a use case for 32x32. BTW Polymod looks cool - right out of the 70's or 80's! As you can see above...

I've had a quick look at it. I've added buffers to MCLK and LRCLK on each board. That reduces the fan-out to acceptable levels. With the existing jumpers for DI and DO that should support the 32x32 case with pins 6, 7, 8, 9 for DI/DO patching as...

Sadly the 12 pin input and output IDC cables are going to interfere with getting the SD card to the edge of the PCB. Those committed to (or for?) big numbers of channels could always put some kind of a cutaway at the top corner of the case to...

Thanks. All looks doable on the main board - at least up to 32x32. 64 and beyond will need a T4.1. I might widen the new board by a few mm so that the T4.1 pin is over the PCB. Realistically, beyond 32x32 is just for fun... I can't very many...

What! Only 64 channels! Seriously, it's great to see your multi-TDM code in action - and the moderate CPU usage is a nice surprise. Did you try without the clock buffer board? What was the outcome? Which DI/DO pin pairs did you end up using? I...

Good to see that you got them working without much trouble! I forgot to mention - 13mm x 3mm tapped spacers work well for board stacking. I'll add some construction notes to the repo in the next day or so.

The Main board and Wings are now live on Tindie if anyone wants to procure via this channel rather than buying boards direct from JLCPCB. Pricing is $US. Tindie: 8x8 Teensy Audio Board Sadly, I couldn't find any cheaper postage, so best to...

Yes, it's always a trade-off. Once you're 'inside the box' it's less important to use balanced lines, as you have good control over interference and a solid earth. The noise impact (less than 3dB) is trivial compared to the PGA's rise in N+D at...

MarkT - thanks for your comment. What's the context - SGTL5000 or this board?

Yes, all that is quite possible, though I'd probably create a custom wing board with an input and output IDC cable. Why not just use the SGTL5000 board for this as it seems that you are only using 2in and 2 out?

I've run some further input tests to explore jvphotog's question about mic preamps. Here's the N+D and ENOB at the input level where distortion starts to rise at each gain setting. The source is a sine wave from a pro 24-bit audio interface...

Yes, it's two layer! Only the top is populated. As above, I went for a slightly larger PCB for adequate ground planes, rather than 4 layers.

jvphotog You could use 100uF all around if you want as long as they fit. The only reason I specified the smaller caps for inputs is that they're driving into 30 k Ohms and will take longer to equalise voltages on start-up as VCOM rises. There's a...

Excellent! Noise and crosstalk shouldn't be any different with multiple boards - they are all main PCB issues that I have pretty much nailed. Substantial ground planes are why the boards are somewhat bigger than strictly needed for just the...

There are no back components in the BOM or placement files. Everything is on the front for the standard set up. You will need to purchase and mount all the connectors, as these are not cost-effective for PCBA. Also, the cost to do one board...

Here's a test with an ancient Electrovoice RE80 that hasn't been dropped too often (despite mainly being used as a bass drum mic). I've left the audio as recorded - Teensy peak indicators were at about 0.8 at the loudest part. The red line in...

The board files are now uploaded to the hardware repository, with full JLCPCB PCBA files for the main PCB and gerbers for all the Wing boards. https://github.com/palmerr23/Teensy8x8AudioBoard Apart from the main PCB, BOM files are indicative...

New PCBA boards have just arrived. A quick test shows CODECs are being programmed and audio inputs / outputs are working. More to follow after more thorough testing. Jonathan, I'll post the PCBA files on the repo as soon as the boards are...

The connection shuffling issue is why I write the dynamic patching example. Looping through arrays is a wonderful thing! The PCBA is complete and waiting for pickup. Monday next week looks like the likely arrival date. Testing should take almost...

I just ran Paul's memory and CPU usage example and (unsurprisingly) you are correct. I will amend the CPU load figures.

Yes, leave in the BCLK inversion - it will make things easier for other hardware creators. I only removed that feature from my solution as I didn't know if that it would be included in 1.60. BTW, thanks for the pull request with the fixes...

I've uploaded the example files. The 16-bit DMA-audio buffer data copying may not be required. I wrote it before I found the bug in the 32-bit code. The example files have no argument in the constructor, so I guess the code is unused .. it's...

Back-seat driver: The files are up in the repo for your perusal. https://github.com/palmerr23/control_TLV320AIC3104

True!

Jonathan, Yes, there will be a separate driver repo linked to the hardware one (control_TLV320AIC3104). I'll move the driver doco across to it when it's there. The mux code is incorporated, as Rob Tillaart's excellent library for the PCA9548...

The XLR board should have *close to* enough gain. The PGAs have 60dB of gain, so a vocalist with a strong voice will be fine, a whisperer not so much! I haven't yet tested this in practice - the XLR connectors haven't arrived yet! Most of my...

New boards ordered. Let's hope they're right this time!

Thanks teensygal, How many are you likely to want? If you're going to use them for a project, you could have a look at the output connector options (Wing boards). Unpopulated, they're only a few dollars each. I've just updated the options on...

The new T4.1 overhang is only a few millimetres. All that would be required to use Pin 32 will be a short flying lead from the DI or DO jumper. A duPont connector would work nicely. BTW, I've never had much success using pogo pins to the bottom...

Yes, I checked both on the Kicad Gerber viewer and JLCPCB PCBA tools and simply missed that I hadn't unchecked the "don't fill areas" option on the JLCPCB Tools settings page. C'est la vie! The benefit for others is that I was working on an...

The PCBA boards came back with no ground plane - my fault. I'll just have to try again!

Thanks J, The item isn't live yet on Tindie, but here's the correct link anyway. https://www.tindie.com/products/palmerr223/teensy-8x8-audio-board/

I have ordered 10 PCBA boards from JLCPCB to ensure everything is correct. They cost $100 US, without headers, including $15 postage to Australia. I also added an optional -5V rail generator on the rear of the board for those applications that...