Hi Troy, love what you're doing here and I have to admire your very professional approach to software engineering, bug fixing and feature requests! I've read the whole thread and although it has been touched upon by a few people, I notice that there hasn't been much mention of usage cases and finished product integration. Haha - that sounds a bit more pompous that I meant
but in reality it's an entirely selfish feature-request before things get more fixed!
In my case I would like a stand-alone DSP crossover with multiple SPDIF/TOSLINK/USB/BT inputs and level attenuation, controlled by a standard IR remote (or possibly a webpage/App). Configuration by USB, outputs SPDIF/TOSLINK/I2S/etc. or internal DAC. Obviously you're pushing the Pico to its limits (and beyond!) so I was thinking of adding another "helper" Pico in a way that compliments what you've already done.
Pico "helper" board
-------------------
USB Config of itself and attached DSPi
WiFi Config/Control(?)
USB Audio Input
Digital Audio Inputs (SPDIF/TOSLINK/I2S/etc.)
Bluetooth Audio Input(?)
IR Receiver Input for Remote Control (Learning?)
ADC Input for motorised linear volume pot
2x Relay outputs for motorised linear volume pot
Quadrature Input for source selection encoder
Input for Mute/Power button on encoder
LED Outputs for source indication
I2C for config of attached DSPi (multiple)
Digital Audio Output (Selectable Pre/Post volume) (SPDIF/TOSLINK/I2S/etc.)
Digital Audio Output to attached DSPi (multiple)
And an amplifier Trigger output for good measure!
So, the helper board would select the external/internal audio source (using IR-remote/encoder/webpage) outputting pre/post-volume loop-through audio for a multi-room system (or alternative HiFi system) and send the main digital audio output to one or more DSPi boards. Multiple DSPi boards for when more outputs/filters are needed for a high-driver-count active loudspeaker and subs. Volume control could be done anywhere in the chain(?), but would be set using IR-remote/volume-pot/webpage - I personally like to use a motorised linear-pot controlled by relays, feeding the analogue output into an ADC. I like this concept as it gives a retro feel to the controls and means you don't need a display to see what the volume level is - opinions may vary! LEDs would indicate active source and Mute state, flashing for bluetooth pairing and USB link-status. The config and other control for the DSPi would be via I2C, which should be plenty fast enough and allow more than one DSPi board to be used simultaneously - although more than two would seem excessive!
I guess you would have to have a second mode of operation for the DSPi, for configuration over I2C, but this could easily be done via a pull-up on a pin(s) which would also indicate the address if more than one board is used. Or you could do an initial setup via USB to set the mode/address, but this would seem a bit more fiddly. For DIY use you would have to program and upgrade all Pico boards via their own USB, but I assume that a finished product could use I2C for transferring the .bin via the helper board to the DSPi board(s)? I don't know if the helper board would reduce the burden on the DSPi board enough to allow more features, but presumably it would allow more interface-type features to be added to the helper board than would be possible with just the DSPi.
I hope you take this selfish request in the way that it was intended!
AJ
