[GreenKeys] TTY to Ethernet Converter or TTYoIP

[John Nagle]

On 8/2/2011 9:01 AM, greenkeys-request at mailman.qth.net wrote:
> On 01/08/2011 02:42, Keelan Lightfoot wrote:
>>> I'm working on a 'TTY to ethernet' converter, that will
>>> eliminate the need for a separate computer entirely. The hardware
>>> design is complete, and I have all the pieces needed to build a
>>> prototype, I just haven't had the time to put one together. The
>>> hardware will occupy a board about the size of a business card,
>>> and will include an Ethernet port for connecting to a network,
>>> and a teletype loop connection (reconfigurable as either half
>>> duplex or full duplex).
>>>
>>> My initial design was going to use a Lantronix XPort, which is a
>>> serial-to-ethernet converter housed in a slightly oversized
>>> through hole ethernet jack. The XPort wasn't capable of anything
>>> lower than 300 baud, 8 bit operation, so I was going to include
>>> a PIC microcontroller to handle the conversion to 45 baud, 5 bit
>>> operation. Then I discovered that the same people that make the
>>> Xport also make the XPort 'pro', which is the same hardware, but
>>> it runs a tiny Linux OS.
>>>
>>> I've spent some time poking around the serial driver firmware
>>> source, and it supports 5 bit operation out of the box (contrary
>>> to the XPort documentation), and with a few changes to the
>>> firmware, I will be able to add 45.45, 50 and 75 baud operation.

     This seems like a good device for that.

     Remember to turn the gap time and the buffer size way down.  The
device has an accumulation timer, which is, by default, 4 character
times.  If you leave it at the default, there will be a delay of 4
character times between hitting a key and having it sent.  At 45 baud,
that's seriously annoying.

     The default buffer size is 2048 chars, and if left at that size,
when you interrupt output, you get to wait for the remaining 2048 chars
to print.  I went through all this with USB to serial converters.  It
can all be made to work, but the modern defaults are far too big. 			

>>> The idea is to allow a teletype to connect to any internet
>>> service that supports telnet, including other teletypes. I've
>>> also been working on a 'TTYoIP' server that would allow a number
>>> of teletypes to be connected together on a virtual loop via the
>>> internet.

     The Xport device, by default, is set up as a client, not a
server. It will need to be reworked so that it initiates connections
to some external server on its own.   If you can do that, you can
eliminate the need for an external computer.

				John Nagle