[GreenKeys] Interface ASR33 to Linux serial port

Michael Katzmann vk2bea at gmail.com
Tue Jan 9 13:15:07 EST 2024 

I did some work on the Linux Prolific driver to get it to work with
arbitrary baud rates (e.g. 110). There are several variants and the one I
had did not give the right speed when set to 100. I was able to reverse
engineer it (with a lot of trial and error) and now AFAIK all the
variants now work.
https://github.com/torvalds/linux/blob/master/drivers/usb/serial/pl2303.c

Michael


On Tue, Jan 9, 2024 at 12:38 PM Eric Moore <mooreericnyc at gmail.com> wrote:

> DriverGenius 4 Port USB to Serial RS232 DB9 Adapter Coverter with 12 X
> LEDs - Win11 & Mac (4XRS232, Metal) https://a.co/d/6xXQ0fy
>
> This is what I use, definitely does 110 baud on all 4 ports, should do
> lower.
>
> Uses the PL2303 I think, the FTDI I have had issues at low speeds.
>
> -Eric
>
>
> On Tue, Jan 9, 2024, 11:13 AM Chuck Rehor <chuck at rehor.com> wrote:
>
>> Hi GreenKeyers,
>>
>>
>>
>> In the past for my RS-232 projects when I’ve needed serial
>> communications, I ran into unexplained problems with USB-to-RS232-Serial
>> converters incorporating the Prolific chipset. Since Prolific has become
>> so, well, prolific, it has a huge market share, so foreign companies have
>> knocked off the Prolific chip and flooded the market with counterfeit chips
>> marked Prolific, but are NOT Prolific brand.  These counterfeit chips have
>> flooded the electronics parts supply chain, and therefore, have been
>> inadvertently used in even legitimate companies' USB adapters (even
>> name-brand companies).  To protect themselves, Prolific finally changed
>> their drivers so that their drivers are on the lookout for bogus chips. I
>> think those Prolific drivers are part of the Microsoft Plug-n-Play
>> devices.  If the new Windows driver finds a counterfeit chip being used on
>> the system, the driver will give a warning and disable the device by
>> overwriting the driver on your system. With the RPi running its version of
>> Linux, I’ve scratched my head trying to get gettys to run right because it
>> might show the login prompt, but either not accept characters, or it
>> accepts characters but would not give me a Password prompt, so I couldn't
>> get logged in. Searching on the internet, I saw other people had problems
>> with the Linux drivers too.
>>
>>
>>
>> So I’ve given up on Prolific and only use devices which use the FTDI
>> chipset. If a device doesn't specifically say it uses the FTDI chipset,
>> chances are it doesn't, so I don’t bother with it.
>>
>>
>>
>> Recently I’ve had great luck with Gearmo 4-Port RS232 to USB FTDI chip
>> Adapter w/RX and TX Status LEDs (
>> https://www.amazon.com/Gearmo-Port-RS232-Adapter-Status/dp/B08P24ZQ1B
>> $44). It comes in a version that doesn't have the status LEDs for a few
>> dollars cheaper, but LEDs are well-worth it when trying to debug something.
>>
>>
>>
>> If you only need one RS-232 port, I can recommend Gearmo's USB to Serial
>> RS-232 Adapter with LED Indicators FTDI Chipset (
>> https://www.amazon.com/gp/product/B00AHYJWWG   $23).
>>
>>
>>
>> The only thing I can't verify is if it goes down to 110 baud (I don't
>> have a 110-baud device in the same location).  I did connect Ports 1 & 2
>> together (via a null modem connector) and opened two putty sessions set for
>> 110 baud, 8 bits, 1 stop, no parity, xon/xoff, and it seemed to work (I
>> could send characters back and forth between windows).  I used putty
>> version 0.78 on Windows 11 and a command line of: "C:\Chuck> putty
>> -serial COM5 -sercfg 110,8,1,n,X" because I could never correctly configure
>> putty with its GUI.  However, when I opened a putty session for 300 baud
>> and kept the other at 110, I expected I couldn’t communicate between them,
>> but lo and behold, it worked anyway, so I’m not sure it actually went down
>> to 110 and 300 baud.  Maybe it defaults to a certain speed if someone tries
>> to give it a speed it can't handle.  Like I said, I don’t have a 110 baud
>> terminal in the same location so I couldn’t really verify 110 or 300 baud
>> operation, but sometime I will and report back.
>>
>>
>>
>> Hope the above helps.
>>
>>
>>
>> Chuck
>> W9CFR
>>
>> On Mon, Jan 8, 2024 at 2:36 PM Tom Lake <tlake at twcny.rr.com> wrote:
>>
>>> I have a PiDP-11 as well and the Teletype works fine with it. I replace
>>> the PiDP-11 with the Pi 5 using the same RS-232 converter and I can’t log
>>> into Linux with the Teletype.
>>>
>>>
>>>
>>> *From:* Michael Katzmann <vk2bea at gmail.com>
>>> *Sent:* Thursday, January 4, 2024 5:33 PM
>>> *To:* tlake at twcny.rr.com
>>> *Cc:* greenkeys at mailman.qth.net
>>> *Subject:* Re: [GreenKeys] Interface ASR33 to Linux serial port
>>>
>>>
>>>
>>> I've got a PiDP11 with a 33 attached.
>>>
>>> Usually the 33 is driven off the PDP11/70 SIMH emulator.
>>>
>>> I tried running the agetty command as you showed and it looks like it
>>> worked (except bash is confused for some reason)
>>>
>>> The OS is Raspbian (32 bit) but its pretty close to Ubuntu (both based
>>> on Debian). I favour Fedora myself!
>>>
>>>
>>>
>>> Michael
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Thu, Jan 4, 2024 at 3:52 PM Tom Lake <tlake at twcny.rr.com> wrote:
>>>
>>> I have an Ubuntu 23.10 system with agetty running on its eight serial
>>> ports. I can hook up most terminals to the ports and login to a bash shell.
>>>
>>> When I try to use a Teletype ASR 33, however, I get the login prompt and
>>> I answer enter the username. If I hit Return, nothing happens. If I hot
>>> Line Feed, the Password prompt is shown.
>>>
>>> After I enter the password (all uppercase) Incorrect password is shown.
>>>
>>>
>>>
>>> Since the prompts are displayed properly, I’m pretty sure the baud rate,
>>> BPS and stop bits are correct. What else can I check?
>>>
>>>
>>>
>>> I start agetty this way:
>>>
>>>
>>>
>>> agetty  -L -U ttyUSB0 110 tty
>>>
>>>
>>>
>>> The -L means it’s a dedicated line, not dial-in. The -U means the
>>> terminal is uppercase only and some upper/lowercase conversions should be
>>> made.
>>>
>>> The port is a USB to serial port (ttyUSB0), baud is 110.
>>>
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>>>
>>> --
>>>
>>>    |\      _,,,---,,_             Michael Katzmann
>>>    /,`.-'`'    -.  ;-;;,_         NV3Z / VK2BEA / G4NYV
>>>   |,4-  ) )-,_. ,\ (  `'-'
>>>  '---''(_/--'  `-'\_)
>>>
>>>
>>> ______________________________________________________________
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>>>
>>> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>>> https://teletype.net/gksearch
>>> >>> 2002-to-present greenkeys archive:
>>> http://mailman.qth.net/pipermail/greenkeys/
>>> >>> 1998-to-2001 greenkeys archive:
>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>>> http://comcents.com/tty/greenkeyssearch.html
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to chuck at rehor.com
>>>
>> ______________________________________________________________
>> GreenKeys mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:GreenKeys at mailman.qth.net
>>
>> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>> https://teletype.net/gksearch
>> >>> 2002-to-present greenkeys archive:
>> http://mailman.qth.net/pipermail/greenkeys/
>> >>> 1998-to-2001 greenkeys archive:
>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>> http://comcents.com/tty/greenkeyssearch.html
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to mooreericnyc at gmail.com
>
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
> https://teletype.net/gksearch
> >>> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> >>> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to vk2bea at gmail.com



-- 
   |\      _,,,---,,_             Michael Katzmann
   /,`.-'`'    -.  ;-;;,_         NV3Z / VK2BEA / G4NYV
  |,4-  ) )-,_. ,\ (  `'-'
 '---''(_/--'  `-'\_)
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