[time-nuts] Re: Ryzen mobos with serial port for Garmin GPS?

[Lux, Jim]

On 11/5/21 11:32 AM, Andy Talbot wrote:
> Use FTDI USB serial ports - you can't go wrong with them.
> https://ftdichip.com/
>
> I have, at the last count, used something like 200 of their FT232 device in
> one form or another on the shack PC.   I know that, because device manager
> has registered up to COM200.  Every time a new one is plugged in, a new COM
> port is set up.
>
> Andy
> www.g4jnt.com
>
>
>
> On Fri, 5 Nov 2021 at 18:26, Alec Teal <alec at unifiedmathematics.com> wrote:
>
>> A friend of mine who lives and breaths this stuff (I wont tell you what
>> he does - but suffice to say he's authoritative) basically said to me on
>> something about serial ports that you can't go wrong with USB stuff,
>> even on Linux.
>>
>> Would that work?
>>
>> Serial ports certainly are getting scarce! You'd get 2 to a board an
>> embarrassingly long time ago!

A caution - FTDI has several series of chips (FT23x, FT245) that wind up 
in commodity USB to Serial/RS-422/etc products. Some of them do not have 
driver support for MacOS post Mojave (MacOS pulled the FTDI driver into 
the kernel, but it only accepts some PID/VID values, etc).

I can't speak to Windows 10 etc since I've not tried it.

I've got a dozen or so RS232 dongles that are now useless in a general 
sense - sure, they work with the old PC, but they lurk waiting to 
frustrate you when you plug them into another computer that doesn't 
support them.


And then, of course, there are the famous FTDI clones which "sometimes" 
work.

For Linux, you may or may not care - depending on libusb, etc. But I've 
had version compatibility issues there, too (Ubuntu, various LTS 
versions we use at work).

Just budget for potential replacements.

And, because this is timenuts - any modem control signal (e.g. RTS) 
going across USB is going to have a 125 microsecond uncertainty due to 
the 8kHz frame rate of USB.