From: Solomon Peachy via rockbox <rockbox_at_lists.haxx.se>
Date: Sat, 1 Apr 2023 07:39:38 -0400

On Sat, Apr 01, 2023 at 12:29:27PM +0200, Michael Sparmann via rockbox wrote:
> I wouldn't see why not - perhaps the RP2040 could also be a good candidate?

The ESP32 is doable, but just barely -- It has more than enough raw
compute performance (dual cores _at_~250MHz) but where it falls flat is
onboard RAM -- It only has 512K on-chip. While it can natively use up to
4MB of off-chip SPI-attached PSRAM, that comes at a signficant
performance penalty.

So while a simple port to an ESP32 is certianly possible, it's not going
to yield great results compared to the current set of targets. With a
lot of additional work, rockbox could be better adapted to handle the
ESP32's limitations (eg directly execute plugins/codecs from flash) but
I don't really see that as being worth the effort, especially when you
consider the lack of a viable portable physical enclousure.

TBH I think a RPi Zero (or some of its similar form-factor clones [0]) is a
much better starting point, and they have far, far more capabilities than an
ESP32, at the same rough price point.

But circling back, the RP2040 is _way_ too limited -- The advertising
copy says "plenty of fast on-chip RAM" but in reality that equates to
just 264KB, an order of magnitude too little for a rockbox port [1] even
if we re-architect rockbox to execute _all_ code from flash.

264KB is even less RAM than the RKNano and ATJ2137-based shovelware mp3
players out there -- and those sport hardware codec engines!

That's the problem with microcontrollers in general; even modern ones
are very RAM limited, and only the highest-end units can work with
external RAM. By the time you add that external RAM, the BOM cost and
PCB footprint is such that you're probably better off with a more
full-featured SoC such as what's on the RPi series, the various Ingenic
parts we already run on, or Allwinner's FC100/V3 series. (Plus, if that
"real" SoC runs Linux, a usable port requires relatively little software
work!)

[0] https://itsfoss.com/raspberry-pi-zero-alternatives/
[1] Or at least a port of anything with sufficient features to be
    recognizable as rockbox.

 - Solomon

-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      _at_pizza:shaftnet dot org   (matrix)
Dowling Park, FL                      speachy (libra.chat)

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Received on 2023-04-01