| From: Stewart C. Russell via talk <[email protected]>
| It's a little hard to find the exact EP32 module used for that simulation.
| That's part of the problem: there are many different chips called ESP32
| /something/, but many of them are incompatible. Some have one core, most have
| two. Some have the ability to take a few megabytes of extra external
| (slow-ish) RAM, many don't. Some are even RISC V in disguise (the new ESP32-C6
| is fully RISC V) , or have a tiny RISC V acting as an Ultra Low Power
| Processor that can do basic electronic logic and while the main processor is
| asleep.
Yes. Espressif has done a terrible job naming these things.
You know the following but others might find it interesting.
Beware: LONG
These SoCs have an amazing collection of features to interact with
devices in the real world. A few parts are not so great (eg. the
Analog to Digital Converters seem to have disappointing accuracy).
It is in the same ballpark as a Raspberry Pi Pico.
ESP32-S? are the ones with the Xtensa main processor(s)
ESP32-C? are the ones with the RISCV processors
The Xtensa-based one have more compute power. It seems like a
reasonable processor. The S3 even has something for accelerating AI
computing (I'm haven't looked to see if it is documented).
The RISCV-based ones are less expensive and seem to be designed to
replace ESP8266 chips. Note the RISCV is 32-bit and doesn't have
an MMU as we know it. Not suitable for Linux.
Espressif also make a confusing set of modules and those are the
things that most boards have. WROOM and WROVER (with
external-to-the-chip RAM and ROM) are the main ones.
I window shop for these on AliExpress. Most ads are unclear about
just what modules they use.
The "camera" variant seems like a lot of bang for the buck. Here's an
example (I don't know anything about this vendor):
<https://www.aliexpress.com/item/1005003804757059.html>
Beware: for this and many other listings you choose a "color" to
select the configuration. If you get it wrong, you get a booby prize
(eg. only an antenna).
The most powerful normal ESP32 board seems to be an ESP32-S3 with 16M
of flash and 8M of RAM (often written N16R8). Two USB connectors are
nice: one is for programming and the other is for whatever your
program wants it to be. Too bad this one requires you to solder the
headers:
<https://www.aliexpress.com/item/1005004617322170.html>
Color 1: $4.92 C3
Color 2: $9.02 S3 N16R8
Color 3: $7.44 S3 N8R2
| > I wonder if uClinux could be ported to ESP32. But not enough to try!
| > It's not clear to me that it would be very useful.
| Apparently it can —
| https://www.cnx-software.com/2021/07/18/linux-5-0-esp32-processor/ - but it's
| doing it via RISC V emulation. I can't see how it would be useful at all,
| though
That's expedient but wasteful and, as you say, unlikely to be useful.
As far as I remember, the Xtensa CPUs have memory protection but not a
sufficiently general MMU for UNIX or Linux. They do have enough RAM
and ROM for ancient and small UNIX-like systems. A maxed-out
PDP-11/45 had 256K of RAM.
---
Post to this mailing list [email protected]
Unsubscribe from this mailing list https://gtalug.org/mailman/listinfo/talk
