Date: Tue, 21 Apr 2015 08:03:57 +0200 From: Hans Petter Selasky <hps@selasky.org> To: ticso@cicely.de, freebsd-usb@freebsd.org Cc: Bernd Walter <ticso@cicely7.cicely.de> Subject: Re: Strange problems with CH340G (uchcom) Message-ID: <5535E84D.2010905@selasky.org> In-Reply-To: <20150420194855.GA29418@cicely7.cicely.de> References: <20150420194855.GA29418@cicely7.cicely.de>
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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 > reading. > The strange thing is that I can see a valid response on a scope just > a few µs 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. --HPS
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