Hi
The serial loader via UART can be extended by any means (Bluetooth, Wifi, etc) as long as the serial connection respects any flow control requirements needed (like XON/XOFF). Some of the loading protocols are binary handshake based so are not critical either.
The SREC protocol has also be used in a system extended via I2C, but such details are usually irrelevant to the serial loader itself since they are external transport systems.
If your question is about implementing the AT command set used by the ESP32 and using Wifi as an updating mechanism this is in use (also with other Wifi modules, such as ATWINC15xx/34xx) but is not included in the serial loader itself (it is included the reference application) since it is typically the application that manages the transfer of the new code and the serial loader just performs the application swap part of the operation.
Regards
Mark
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