[sdiy] Electrosmith Eurorack DSP platform

Eric Brombaugh ebrombaugh at gmail.com
Thu Jan 27 18:23:21 CET 2022


On 1/27/22 02:51, cheater cheater wrote:
> On Thu, Jan 27, 2022 at 1:33 AM Eric Brombaugh via Synth-diy
> <synth-diy at synth-diy.org> wrote:
>>
>> I've done one port to RP2040 so far and migrating is definitely a shock
>> to the system. A few things I've noticed:
>>
>> * The SDK libraries cover a lot of basic stuff you'd want to do, but not
>> everything that STM32 HAL does. Be prepared to "roll your own".
> 
> Could you give some examples please?

In particular, there is no I2S port and the example they provide for the 
PIO is output-only. I was able to modify their approach to provide full 
duplex (in + out to a codec) and it works fine, but it's not nearly as 
easy to do as in STM32-land.

>> * The RP2040 ADC is a lot noisier than anything on STM32. They claim
>> 12-bits resolution and 10-bit accuracy. Expect less unless you're doing
>> a lot of integration.
> 
> How is the RP2040 as a massive amount of audio DACs?

You could certainly do it. With eight PIO state machines you could 
easily get 16 channels of I2S audio output and probably more if you 
tried really hard. There's plenty of bandwidth on the internal buses for 
stuff like that. Question is how you would source all the data that kind 
of design would need - even 16 channels would more than saturate the 
full-speed USB port at 48k. Generating the data programatically or even 
just reading it from flash would likewise be a squeeze.

Eric



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