Wemos/Lolin S2 Mini w/ESP32-S2, D1 Mini pin compatible

[durapensa]

I ordered the $4 Wemos/Lolin S2 Mini to give it a try with [pre-loaded] MicroPython. I'll build & test Tasmota using the ESP32-S2 board definition.

More on this board at the wemos.cc wiki & the CNX Software writeup.

[barbudor]

I think ESP32-S2 are a great stuff for CircuitPython because CircuitPython mount the internal flash as a mass storage and you can easily edit or drop *.py file directly.
For MicroPython, this doesn't bring much value over a standard ESP32
For Tasmota, ESP32-C3 is more interresting as even cheaper and a good replacement for ESP8266

[durapensa]

I plan to try some existing ESP32-S2 CircuitPython builds with this board, and likely a new board definition for CP will be trivial. I'd also like to try to load a UF2 bootloader (something the ESP32 cannot do, to my knowledge).

Even for MicroPython, the advantage of ESP32-S2 over ESP32 is price - it's a cheaper chip to produce and seems it or the ESP32-C3 may be the high-volume successor to ESP8266. Without knowing Espressif's constraints for producing these two chips (if those constraints differ at all), I guess only time & market will decide this one.

Perhaps Wemos/Lolin will make a C3 Mini too - I don't know why they chose ESP32-S2 over ESP32-C3.

For this Wemos S2 Mini, getting Tasmota's Berry scripting on a $4 D1 Mini form factor is a big boon.

[s-hadinger]

Take a look at Berry scripting. It's similar to Python but much lighter in resources needs

[durapensa]

Take a look at Berry scripting. It's similar to Python but much lighter in resources needs

See the last sentence in the block you replied to. 🙂

[sfromis]

One reason for not choosing the C3 is that it is very new in the market, only recently out of prototype stage, and some people may not want to do the bleeding on the leading edge. Outside of potential philosophical preferences for Risc-V, the advantages of C3 are small, and production delta cost may not be much of a factor in how Espressif choose to price chips.

[Jason2866]

S2 Arduino has a bug with flash read/write which makes LittleFS to fail. See espressif/arduino-esp32#5550
There is no need to wait for Lolin to do C3 boards. There are already nice ones from others

[barbudor]

... it would be pretty simple to make a board like the "narrow" breadboard-compatible D1 Mini

Don't ask, they already made it
With Ch340 :
€ 2,09 | CH340G USB-TTL converter for ESP8266 -ESP07 / ESP12 to WIFI D1 mini, with pin-headers set.
https://a.aliexpress.com/_ujCon0

Without Ch340, better for battery powered
€ 1,36 | RobotDyn WIFI D1 mini - ESP-07 Shield, with pin-headers set compatible with Arduino boards WI-FI ESP8266 for DIY Electronic
https://a.aliexpress.com/_uIdnMA

[durapensa]

I've seen people do these module replacements. A nice thing about the S2 Mini is that it uses a bare ESP32-S2FN4R2 SoC (all flash & PSRAM & USB controller in-package) rather than a module, so smaller with fewer external components & more pins.

[blakadder]

There already is a small (but taller) footprint C3 dev board - https://t.ly/VPyw

[barbudor]

A pity they have soldered the M module on it instead of putting an edge-connector

[durapensa]

I had my eye on that C3 engineering sample dev board & its specs.

They also make a board with ESP-C3-12F module (soldered, no edge connector), ESP-C3-12F-KIT (specs).

[Jason2866]

The ESP32-S2 wemos board do not have a usb-serial converter on board! For flashing the chip USB port is used. Flashing is not possible without some (inter)action. I do not like this with a dev board. Imho a cheap design.

[durapensa]

For a normal Tasmota install, I agree that TinyUF2 is unnecessary. Getting Tasmota installation to play nice with boards that have TinyUF2 factory-installed (in ROM or in flash) would be nice. In the case of tinkering with this new S2 Mini, I'd like the option of using TinyUF2 & switching firmware without erase or complete flash, if all partitions can fit & co-exist in 4MB flash.

Looking at platformio-core/Tasmota/esp32_partition_app1572k_spiffs983k.csv from a recent build, 1572k is the smallest ota_x size I found, and platformio-core/Tasmota/build_output/firmware/tasmota32.bin is 1244k. I'm wondering if the 1408k size example from the TinyUF2 docs can be reduced, or if I should shave off from the 960k FAT partition to make room for a SPIFFS partition and whether this has a minimum size requirement too.

[Jason2866]

Partitions can be defined, easy. So we did for Tasmota. The problem with UF2 is you have to use the predefined ones (factory flashed). If you need a different scheme you have to reflash (the usual old way). I stopped at this point for Tasmota...
Is it possible to reduce the FAT partition? If not this would be the next killer point for bigger projects. Loosing 256k (uf2 loader) and 960k (FAT)! For a program that does more than "Hello World" a no go with a device with 4MB flash.
The 1244k size of Tasmota is only reached by using our own Tasmota Arduino core. Using the standard core will need 245k more of flash. Imho anything lower 1500k free for program is a design fail

Long story short: Tasmota will not run with uf2 on a 4MB device

[Jason2866]

For the S2 it makes no sense at all to use uf2. The inbuilt DFU mode works without problems. Just the manual steps are not comfortable. Windows setup (installing driver) is the tricky part. Many people will fail here. Espressif describes this badly and the mandantory part is well hidden.

[durapensa]

I'm not suggesting that UF2 be a default installation method or built-in for Tasmota for ESP32-S2 boards, only that a method to install Tasmota on UF2-enabled boards, without wiping out UF2 or other partitions, be documented (I'll document it). Some ESP32-S2 boards come with UF2 factory-installed in flash, particularly the CircuitPython focused boards (also, it's CP that uses the FAT partition), and I'll install UF2 on an S2 Mini to tinker with it.

A workaround for the FAT/SPIFFS partitioning issue could be to distribute a tasmota32s2.uf2 without LittleFS and with a note that users wanting LittleFS must perform a complete/erase DFU flash to install a full tasmota32s2.bin. Likewise, Tasmotizer could be tweaked to provide these options too upon detecting a board with UF2 in a flash partition.

[Jason2866]

Why? Everything is easy to reflash. Doing a special (crippled) build will make more issues than it solves.
Since Tasmota is Open Source maybe someone is doing it. I think Theo will not be a fan of such a special version.

[Jason2866]

We do not disagree. But for a development board i want the easiest way to program.