I had simillar issue - mqtt client running at esp32-s3 was disconnecting from its broker running at AWS (IoT Core) after a few seconds. It was regardless of mqtt_cfg.network.refresh_connection_after_ms setting to 0 value at the esp32 mqtt client library.

I had 2 devices connected, and mqtt client ...

Thanks a lot - it helps !

Thank you. In paralel I've also found HHD Device Monitoring Studio ( https://www.hhdsoftware.com/Downloads/device-monitoring-studio ). Its free version is good enough to sniff / log / depict all Serial Port communication under windows and compare with what esptool.py does (with skip 'stub' download ...

Ok, one more thing was to comment out loader_spi_attach_cmd(), as it was causing some error on ESP side. It's possible the spi config value needs to be more sophisticated than the default proposed. It looks to be somehow working w/o the function.

esp_loader_error_t esp_loader_connect(esp_loader ...

Thank you. Yes, I've just found a descriptin of the flash upload protocol: https://github.com/espressif/esptool/wiki/Serial-Protocol

After porting it (mentioned functions, but also those filesystem related) into STM32 project and an attempt to run it with ESP8266 board there are a couple of ...

Hello Angus,

thank you for sharing the link! :-)

I went throught the esp-serial-flasher project sources and following came into my mind:

1. is it using "a protocol" (SLIP_send_delimiter()/SLIP_send() functions) which is compatible with the one used in existing esptool.py (so it has also a chance ...

Similar thread under a name 'IDF and ESPTOOL_PY Licence Clarification Request' is here: viewtopic.php?f=13&t=13805 .

Hello Dear Friends from Espressif,

Allowing to upload (flash, like from esptool.py) ESP32 (and maybe even ESP8266 as well) from other host MCUs like STM32 by software written in C or C++ (a template / example project for that) would bring a value.

It may have sense to share what you have on it ...