From: Johan Hovold <johan@kernel.org>
To: "Michael G. Katzmann" <michaelk@IEEE.org>
Cc: charles-yeh@prolific.com.tw, linux-serial@vger.kernel.org,
linux-usb@vger.kernel.org, Charles Yeh <charlesyeh522@gmail.com>,
Joe Abbott <jabbott@rollanet.org>
Subject: Re: non-standard baud rates with Prolific 2303 USB-serial
Date: Mon, 22 Feb 2021 14:18:38 +0100 [thread overview]
Message-ID: <YDOvLseYXaUHs0lS@hovoldconsulting.com> (raw)
In-Reply-To: <e2dcc839-3b43-2c80-6ad1-2d97e639b46a@IEEE.org>
On Mon, Feb 22, 2021 at 07:39:42AM -0500, Michael G. Katzmann wrote:
> On 2/22/21 3:52 AM, Johan Hovold wrote:
> > Does your updated algorithm also result in 110 baud (8n1) being encoded
> > as:
> >
> > a8 a6 01 80 00 02 07
> >
> > And are you using some official Prolific Windows driver or something
> > that came with the device?
>
> Johan,
>
> On Windows I did not install a new driver. It was recognized by the
> system and uses the Microsoft provided Prolific driver Ver 3.8.38.2.
Thanks for confirming. Then this sounds like something which Prolific
should be very well aware of.
> On windows everything looks fine (no sign of distress (i.e. no yellow
> caution triangle)).
>
> Where should I look for the encoding (a8 a6 01 80 00 02 07) ? (110bd
> encodes as 80 00 C3 54 using the algorithm I described))
That was the encoding used by Joe's device (same driver I think) for
110n81.
It may not work with your device, but 0x10000 could just be a
2-prescaler bit:
32 * 12*10^6 / (2 * 0x6a8 * 4^5) = ~110.03521126760563380282
where as you would have:
32 * 12*10^6 / (0x354 * 4^6) = ~110.03521126760563380282
Could you try hardcoding 0x1a6a8 and and see if you end up with 110 bd?
> > I tried asking Prolific about this but I'm still not sure whether these
> > are official chips or counterfeit. 0x0300 is supposed to be a PL2303TA
> > and Prolific claims that the current driver is working fine with these
> > so we'd need to key off something more than just bcdDevice.
Johan
next prev parent reply other threads:[~2021-02-22 13:21 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3aee5708-7961-f464-8c5f-6685d96920d6@IEEE.org>
[not found] ` <dc3458f1-830b-284b-3464-20124dc3900a@IEEE.org>
2021-02-22 8:52 ` non-standard baud rates with Prolific 2303 USB-serial Johan Hovold
2021-02-22 12:39 ` Michael G. Katzmann
2021-02-22 13:18 ` Johan Hovold [this message]
[not found] ` <fb1489c2-b972-619b-b7ce-4ae8e1d2cc0f@IEEE.org>
2021-02-22 15:34 ` Johan Hovold
2021-02-22 15:42 ` Michael G. Katzmann
2021-02-22 15:50 ` Johan Hovold
2021-02-22 16:37 ` Michael G. Katzmann
2021-02-22 16:48 ` Johan Hovold
2021-02-24 23:08 ` Joe Abbott
2021-02-25 8:44 ` Johan Hovold
[not found] ` <43da22ced8e14442bbc8babea77e4ed7@MailHC2.prolific.com.tw>
2021-02-23 10:18 ` Johan Hovold
2021-02-23 13:25 ` Michael G. Katzmann
2021-02-23 14:58 ` Michael G. Katzmann
2021-02-23 15:43 ` Johan Hovold
2021-02-23 15:57 ` Michael G. Katzmann
2021-02-23 16:14 ` Johan Hovold
2021-02-23 16:30 ` Michael G. Katzmann
2021-02-23 16:52 ` Johan Hovold
2021-02-23 19:15 ` Michael G. Katzmann
2021-02-24 17:04 ` Johan Hovold
2021-02-24 18:13 ` Michael G. Katzmann
2021-02-25 8:42 ` Johan Hovold
2021-04-08 15:35 ` Johan Hovold
2021-02-24 7:34 ` Charles Yeh
2021-02-24 17:00 ` Johan Hovold
2021-02-24 17:12 ` Michael G. Katzmann
2021-03-05 9:32 ` Charles Yeh
2021-03-05 9:36 ` Johan Hovold
2021-03-06 20:18 ` Michael G. Katzmann
2021-03-07 4:15 ` Michael G. Katzmann
2021-03-11 16:08 ` Johan Hovold
2021-03-12 13:17 ` Michael G. Katzmann
2021-03-12 13:44 ` Johan Hovold
2021-03-12 20:29 ` Michael G. Katzmann
2021-03-13 1:28 ` Michael G. Katzmann
2021-03-15 9:07 ` Johan Hovold
2021-03-15 10:07 ` Charles Yeh
2021-03-15 10:24 ` Johan Hovold
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