Cannot switch LoPy4 to download mode with Expansion Board 3.0 on Windows10

[Verkehrsrot]

I'm using a LoPy4 on Expansion Board 3.0 as native ESP32. I'm uploading my code with esptool.py using PlatformIO IDE.

This works smooth if i set the LoPy manually to download mode by connecting G23 to GND while pressing Reset.

My expectation was that this process is automated by esptool when using the expansion board 3.0, but it doesn't work.

The USB connection is working, if i open serial terminal i can see the serial prints of my app running on the LoPy4.

So it seems, only the switching procedure in esptool.py to activate the download mode does not work.

What's the solution? Changing USB driver? If so, what driver is needed?

[robert-hh]

@verkehrsrot Sorry, I do not know a documentation of the Pycom method. I also do not expect that the Pycom method will be implemented by esptool.py, since almost every other ESP32 board maker implements the DTR/RTS method.

[Verkehrsrot]

@robert-hh Thanks for this clarification, saves me wasting time to figure out this is a feature, not a bug.

So, could be a good feature enhancement for esptool.py to implement the pycom proprietary bootloader switch mode. Is it documented somewhere how it works?

[robert-hh]

@verkehrsrot esptools.py expects a certain switch logig on the board to set the device into update mode. That logic is not implemented by the pycom expansion boards.
If you download firmware packages from Pycom, use the Pycom updater. It supports the Expansion Board 3 switch mode.