Raspberry Pi 5 and CM5 as players and convolvers with lotsa analog ports

[john61ct]

Google says, HiFiBerry "DAC+ DSP" can operate completely independently of the Pi after programming!!!

[EDIT this post and subsequent are NOT about DAC8x]
Then the RPI5 can be repurposed elsewhere in the system?

So, use RPI5 (or SigmaStudio?) to program the DAC+ DSP, those settings are stored in its EEPROM.

Then use it to configure other DAC+ DSP, and/or could use it

to run DSPi units

or as a standalone passthrough CamillaDSP node at a point where lotsa taps are needed

or once the system is "in production" just as a player, e.g. squeezelite rendering upstream of the analog preamp.

seems to good to be true??

keyword: Modularised DSP

 

[phofman]

Google says, HiFiBerry DAC8x can operate completely independently of the Pi after programming!!!

Then the RPI5 can be repurposed elsewhere in the system?

So, use RPI5 (or SigmaStudio?) to program the DAC8x, those settings are stored in its EEPROM.

It's necessary to verify what LLMs say, especially the low-performance one provided by Google for free.

Just look at the DAC8x board. It contains 4 x PCM5122A chips and one EEPROM (U1). That U1 is right next to I2C EEPROM pins (27/28), with traces visible to them. That EEPROM is just HAT ID EEPROM https://github.com/raspberrypi/hats .

Then you have the driver for the DAC8x. Overlay is dtoverlay=hifiberry-dac8x. So search for hifiberry-dac8x in https://github.com/search?q=repo:raspberrypi/linux hifiberry-dac8x&type=code

You will see the corresponding overlay code https://github.com/raspberrypi/linu.../dts/overlays/hifiberry-dac8x-overlay.dts#L49 - no I2C bus configured, dummy_codec, only one GPIO used (for ADC board detection).

Another search result is the actual driver code referenced by the layout https://github.com/raspberrypi/linu...9ec/sound/soc/bcm/rpi-simple-soundcard.c#L521 . The relevant codes are trivial and do not show any config communication with the codecs https://github.com/raspberrypi/linu...ound/soc/bcm/rpi-simple-soundcard.c#L412-L416 , https://github.com/raspberrypi/linu...ound/soc/bcm/rpi-simple-soundcard.c#L400-L410 . All that driver does is configure the I2S transmitter to be master.

So no, RPi does no configuration, but logically you need some I2S data bus for fetching audio data to those DAC chips. Of course you do not need RPi for the operation, if you have a different I2S bus (e.g. from some hardware DSP).

So if you have a 24ch I2S, you certainly can hook 3 8ch I2S DAC boards. But I very much doubt that's the case as I2S transmitters with more than 8 channels are quite rare.

 

[john61ct]

EDITED to correct my brain fart.

Removed everything I thought now irrelevant.

I am an rPI noob, and most of that code stuff is way over my paygrade

...

The "DAC+ DSP" is the only DSP in the chain in this scenario.

There are 6 analog INPUT channels from the line-level "switcher / master source"

So to simplify, forget frequency / magnitude aspect and the multiple crossovers within e.g. the Front L/R pair channel

If I just want to say, manage timing delays / phase alignment tuning between those six input channels, this can be done with one DAC+ DSP unit per pair, a total of three units, each fed by a separate "stereo" ADC.

With my previous thinking, I would have needed three rPi left in place fulltime.

However now it seems the three DAC+ DSP HAT DSP nodes can be left in place without the RPI5 used to configure them, correct?

Yes a windows box is also needed for SigmaStudio as below, tx somebodyelse

 

[somebodyelse]

The DAC8x is the only DSP in the chain in this scenario.

Your post confirmed the three DAC8x HAT DSP nodes can be left in place without the RPI5 used to configure them, correct?

Is a windows box also needed for SigmaStudio?

I think Google's AI mixed up HifiBerry's boards, and passed that confusion on to you. The DAC8X is just a DAC and has no DSP, like almost all of their DAC boards. The "DAC+ DSP", DSP Addon and Beocreate are the only boards with an onboard ADAU1451 DSP which can be programmed from SigmaStudio and can operate stand-alone after programming. The DSP Add-on is not compatible with the DAC8X according to the product page. SigmaStudio does need Windows (hardware or virtual machine), and can't run on linux via Wine because it won't start if it can't find the driver for the USB programmer. This is particularly frustrating because if you're using a Pi you don't need the programmer - you just run SigmaTCP on the Pi and do the programming via the network.

 

[phofman]

I am afraid a project like this will require some understanding of the hardware audio basics. IMO you will have to learn a bit about I2S, (compared to I2C which is something else), read the intro section of the PCM5122 datasheet to understand what that DAC actually does (and the hat as that hat is just 4 those DACs on a single PCB).

Your post confirmed the three DAC8x HAT DSP nodes can be left in place without the RPI5 used to configure them, correct?

You can use as many DAC8x boards as you want because they need no configuration (hardware mode of PCM5122, as described in its datasheet), but you need 8 channels of I2S for each board. RPi5 can output only 8 channels - i.e. only one DAC8x board (i.e. 4 stereo PCM5122 DAC chips).

 

[john61ct]

I think Google's AI mixed up HifiBerry's boards, and passed that confusion on to you.

Yes, sorry. Could just be me, old brain crossed wires.

The "DAC+ DSP" is the unit I've been focusing on.

Apparently all that is needed after programming is TOSLink input and 5V power on GPIO, processed signal comes out the analog RCA output.

I will investigate the HiFiBerry "DSP Addon" to see what other line-level devices support that mode.

The amplifier aspect of the Beocreate is unlikely to interest me.

Are you certain it is the ADAU1451 DSP ?


> SigmaStudio does need Windows

Thanks for clarifying

> USB programmer

so that is from Windows, via the RPI5 the HAT is temporarily mounted on?

> run SigmaTCP on the Pi and do the programming via the network

I'm happy to go either way. Are there any pro's & cons between the two as far as SigmaStudio functionality, ease of learning etc?

 

[john61ct]

My abject apologies, DAC+ DSP was what I meant DAC8x was a brain fart

maybe even a shart.

If you're willing please go to the top of the page and re-read with that in mind.

Plus ELI5, as stated my RPI5 and DSP knowledge are at very low points, just starting the learning curve.

Just look at the DAC8x board

 

[john61ct]

So I believe I2S is out of the picture (Whew!) just S/PDIF TOSlink in, RCA analog out.

I plan to use miniDSP's PocketADC per pair of channels, so x3.

Unless good SQ alternatives can be found that are less expensive.

 

[somebodyelse]

Are you certain it is the ADAU1451 DSP ?

That's what's on the DAC+DSP I picked up cheap a while back. I've not used it much, or tried using it in stand-alone mode. I didn't much like HifiBerryOS, and having to run Windows in a VM was frustrating (I don't have any Windows PCs.) The documentation wasn't up to much either - not sure if it's improved any since then.

> USB programmer

so that is from Windows, via the RPI5 the HAT is temporarily mounted on?

No. Most ADAU14xx boards expose pins for a programming interface, and that's what the USB programmer would connect to. I think the programmer is a USB to I2C adapter. On the Pi you would just run SigmaTCP and give the IP address in SigmaStudio - the software accepts the info over the network and sends it via the Pi's onboard I2C. IIRC it was included in HifiBerryOS - it's a few years since I did anything with it.

 

[john61ct]

That clarifies some, thanks. and I guess I'll understand more as I move forward.

Seems like SS shouldn't be the first DSP tool in the learning curve anyway.

I plan to start with REW, maybe CamillaDSP or a version of Hang Loose as Convolver

 

[somebodyelse]

Seems like SS shouldn't be the first DSP tool in the learning curve anyway.

Definitely not. It's more of a graphical programming environment than a DSP tool, and requires a good understanding of how the underlying hardware is connected.

 

[john61ct]

Which low-cost HiFiBerry DSP units can be integrated with DAC8x ?

Say if only one or two pair of the channels actually need DSP'ing

or later I decide to DSP more of them?

Apparently only the 2-channel DACs are compatible with the HiFiBerry DSP add-on board ?

DAC2 HD
DAC2 Pro
DAC2 ADC Pro
Digi2 Pro

I really like the idea that once programmed, the DAC and this DSP board can run standalone without the RPI5, it's only needed for the setup stage, or if tweaking is needed later?

 

[melomane13]

Which low-cost HiFiBerry DSP units can be integrated with DAC8x ?

no one
DAC8x is ideal with camilladsp

 

[somebodyelse]

Which low-cost HiFiBerry DSP units can be integrated with DAC8x ?

Say if only one or two pair of the channels actually need DSP'ing

or later I decide to DSP more of them?

Apparently only the 2-channel DACs are compatible with the HiFiBerry DSP add-on board ?

DAC2 HD
DAC2 Pro
DAC2 ADC Pro
Digi2 Pro

I really like the idea that once programmed, the DAC and this DSP board can run standalone without the RPI5, it's only needed for the setup stage, or if tweaking is needed later?

Short answer: None - as you've seen, only the 2 channel boards are officially supported.
Longer answer: The DSPs do expose i2s so if you know what you're doing you can attach other things to them, but it's not supported so you're on your own. You might be able to make it work with 2 of the 8 channels of the DAC8X, but there'll be a good deal of learning before you get there.

 

[john61ct]

no one
DAC8x is ideal with camilladsp

Hang Loose also right?

You might be able to make it work with 2 of the 8 channels of the DAC8X, but there'll be a good deal of learning before you get there.

OK thanks both for clarifying

 

[john61ct]

RaspberryPi DIYer wanted, sponsor piBrick Pocket-CM5 project

Raspberry Pi 5 project - handheld "cyberdeck" with keyboard and AMOLED screen https://www.notebookcheck.net/piBrick-Pocket-CM5-Raspberry-Pi-handheld-with-keyboard-and-AMOLED-unveiled.1311677.0.html I want one bad, maybe more than one, willing to collaborate for free, maybe help share risk I...

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[john61ct]

Given an RPi5, say 32 48kHz channels I/O over USB or AVP, assuming ALSA/JACK/PipeWire routing all working

Is there a difference in channel count processing capacity between HLC and CamillaDSP ?

I don't think FIR tap-length will be an issue, and I'm not much concerned about latency, but is there a difference there?

It seems CamillaDSP is easier for IIR filters out of MSO or REW?