On 04/20/15 21:48, Bernd Walter wrote:
I tried to flash an ESP8266 with the onboard CH340.
The same board works fine when I use a CP2102 instead of the CH340.
Flashing requires a python tool, which sends a SLIP encoded request
and expects a SLIP encoded response with 115200@8n1.
The read function however times out receiving the response without
getting a single byte, even if I add a high delay between sending and
The strange thing is that I can see a valid response on a scope just
a few ┬Ás after the request completes, while the receiver don't even
see the first byte.
If however I physically loopback the CH340 it receives it's own request
just fine.
Two CH340 xconnected work fine too.
Same when I xconnect a CH340 and a CP2102.
Now I'm completely out of ideas, why the python tool has problems
to see the response data with the CH340.

Try using:

usbdump -i usbusX -f Y -vvv -s 65536

And see if the reply is seen by the USB ... maybe it is a timing issue like one character at a time instead of a word.

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