[GreenKeys] Nagle's teletype board key part nearing end of life

[eric]

On 2021-03-28 08:40, W2HX wrote:
> It would seem to me, someone with the requisite skills might consider
> cooking up our own UART using maybe CPLD or something. Or maybe
> simpler, using an Arduino somehow. That project could be extended to
> have a USB interface. Seems we may have to "roll our own" at some
> point when all these chips disappear.
> 73 Eugene W2HX

I did this a couple of years ago and manufactured a pretty good sized 
run of them, so there are quite a few floating around. Jordan Cunningham 
had another run of them made this past year but I'm not aware if he's 
shipped any yet.  They are out there, though.
https://www.heepy.net/index.php/USB-teletype   The firmware source code 
is on github if you want to make your own, too.   
https://github.com/epvuc/usb-tty

As you describe, it looks like a USB serial port to the computer. 
There's a configuration mode which lets you configure baud rate 
arbitrarily (up to about 600 baud or so). There's a passthrough mode 
where it looks like the pl2303, and also a smart mode where it 
translates ITA-2 to/from ASCII and does various other stuff.

eric


> 
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net
> <greenkeys-bounces at mailman.qth.net> On Behalf Of s shumaker
> Sent: Saturday, March 27, 2021 11:54 PM
> To: greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] Nagle's teletype board key part nearing end of 
> life
> 
> I have a recently acquired (as in two weeks ago)   a CP2102N-EB that
> is cheerfully talking to itself on loopback at 110 baud  in prep for
> connecting to an ASR33.   Port selection in device properties goes as
> low as 75 baud without tinkering with the "Baud-Rate Aliasing tool".
> That may not solve your 45 baud rate problem  but the doc assertion
> that the unit won't work below 300 appears inaccurate and suggests
> some testing might be in order to see if it's unsupported but still
> present.....
> 
> Steve
> 
> 
> 
> On 3/27/2021 2:25 PM, John Nagle wrote:
>> My USD to serial board, described here:
>> 
>> https://github.com/John-Nagle/ttyloopdriver
>> 
>> uses the SiLab CP2102 USB to serial port part.
>> 
>> As of March 2021, the SiLabs CP2102 USB to serial part is "not
>> recommended for new designs". The "drop in replacement" CP2012N will
>> not work. It will not run at speeds below 300 baud.
>> 
>> From SiLabs' porting guide: "Baud Rate Aliasing is a feature that
>> allows a device to use a pre-defined baud rate in place of a baud rate
>> that is requested by the user. For example, a device using Baud Rate
>> Aliasing can be programmed to use a baud rate of 45 bps whenever 300
>> bps is requested. Baud Rate Aliasing is not supported on the CP2102N.
>> If Baud Rate Aliasing is used in a CP2102/9 design, the CP2102N is
>> incompatible as a replacement."
>> 
>> Ref:
>> https://www.silabs.com/documents/public/application-notes/an976-cp2102
>> -3-4-9-to-cp2102n-porting-guide.pdf
>> 
>> It's become difficult to find serial devices that will run at 45 baud.
>> The CP2102 was one of the last. It's still available, so if you plan
>> to build that board, stock up now.
>> 
>>                 John Nagle
>> 
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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
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> 
> 
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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
> 
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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
> 
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