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

[Mike Douglas]

 A possible alternative is to let the host computer use a standard baud rate (e.g., 9600) and have the processor on the interface board throttle the host with a handshake line. I've done this with a 60ma interface board I've recently designed and it works fine.

Mike

     On Sunday, March 28, 2021, 09:42:41 AM CST, W2HX <w2hx at w2hx.com> 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

-----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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>
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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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