[GreenKeys] Support for serial ports

[Chris Elmquist]

I took a slightly different approach to this problem--  which was to put
a small microcontroller (Atmel ATTiny2313) between the upstream serial
port and the TTY.

This micro does speed conversion from 9600 baud and manages hardware flow
control to the PC, Mac, USB to serial or terminal server it connects
to and the 110 baud TTY.  It also adds delays for CR and LF after they
are sent to the TTY which is another feature that modern Linux, Mac and
other platforms have forgotten about.

I put this micro inside one of those Black Box RS232 to 20mA converters
and so it is pretty much a transparent solution.

Now, my ASR-33 runs at 9600 baud, 8-bits, no parity instead of 110 baud,
7-bits, even parity and it doesn't munge characters when returning the
carriage or feeding the paper.   The delays are true time delays, not
sending of NUL or RUBOUT so you can punch a binary tape through this
scheme too with the only cost being a slight pause when 0x0d or 0x0a
goes by.

Chris N0JCF


On Wednesday (06/15/2011 at 02:57PM -0500), Randy and Sherry Guttery wrote:
> On 6/15/2011 11:13 AM, Bryan Brodie wrote:
> > I was never able to configure
> > MacOS/UNIX to transmit / receive over the serial port at less than
> > 9600 baud.
> That may be either a limitation of the USB <-> Serial 
> interface - or the software you're using.
> > I had believed that the USB to serial solutions didn't work
> > for TTYs, but it sounds like some of you guys have it working in UNIX.
> And PCs.  Can't try with Macs anymore - as the last one we 
> had (not counting the relics in storage) is gone.
> > If anyone has ever successfully connected a Mac to a TTY, I'd love
> > more details
> Well, back when Macs had "real" serial ports - it was easy 
> to configure those ports to interface with a TTY.  These new 
> (Intel) Macs - I don't have any experience with.
> 
> In theory, at least - the CP2102EK that's mentioned here 
> every-so-often should work with Macs just fine - since you 
> can "substitute" a "real" baud rate for a "requested" one.
> 
> That would be the direction I'd look at...
> 
> -- 
> randy guttery
> 
> A Tender Tale - a page dedicated to those Ships and Crews
> so vital to the United States Silent Service:
> http://tendertale.com
> 
> 
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-- 
Chris Elmquist