ESPTool entering Bootloader, RTS / DTR sequence

[Ing-Dom]

I have a question regarding the Auo-program mechanism.

I have ONE specific computer where the timing of the DTR and RTS signals are in a way entering bootloader does not work.

The esptool does following sequence:

pull RTS low ( => put ESP into reset)
sleep
pull DTR low ( => should pull GPIO0 to low, but with RTS beeing low it result in GPIO beeing HIGH)
set RTS high ( => to late, buddy...)
sleep
set DTR high ( => back to normal)
https://github.com/espressif/esptool/bl ... y#L97-L106

thats a picture of DTR (yellow) and RTS (blue) of a CH340C, while trying to "read_mac" with esptool.py (4.7.4).

20241018_171420_C.jpg (1.16 MiB) Viewed 1400 times

that results in

Using tool-esptoolpy@4.7.4 package
esptool.py v4.7.4
Serial port COM2
Connecting......................................
A fatal error occurred: Failed to connect to Espressif device: No serial data received.

and the reason seems to be the delay between DTR low and RTS high causing GPIO to be 1 du to the transistor logic..

20241018_171420.jpg (1.07 MiB) Viewed 1400 times

this seems by design, why is that? And how do I solve it?
On other computers the delay between pull DTR low and set RTS high is much less, so it works..