[GreenKeys] TTY-CONNECT loop adapter thingy

[gil smith]

Hi folks:

Well, an update on the new 232-to-loop adapter board for hooking up the 
Dovetrons to your machines (and doing other stuff).  I am calling it 
TTY-CONNECT, unless I think of something with a catchier ring to it.  We 
discussed a wish-list and some prelim specs many months ago, but I have not 
had much spare time.  Now that the Dovetrons are shipping I need to get 
this moving.

Some of you have my first-generation board, TTY-232, from a few years 
ago.  It had a full/half-duplex high-voltage loop (for M14/15/19/28...), a 
half-duplex low-voltage loop (for M32/33...), and an RS-232 
interface.  Loop supplies were all built into the case, and everything was 
opto-isolated.  It also had an optional microcontroller, which I set up to 
automatically convert 19200-baud ascii on the 232 port, to 60/66/75/100-wpm 
baudot, or 110-baud ascii, on either of the tty loops.  With no micro 
installed, the 232 port must be driven with the appropriate speed baudot or 
ascii stream, as needed -- this can be done by Bytheway's RTTYArt program, 
or Buzbee's HeavyMetal program.  You can also connect your Dovetron's 232 
output to tty loops with this board, provided the machines are operating at 
the appropriate WPM.

Which brings us to TTY-CONNECT.  For this board, since the 232 output from 
a TU is likely to be 60 or 75-wpm and your machine may not, I want to add 
baudot-to-baudot speed conversion as well (yes, there are buffering 
limitations for hi-to-low speed).  Also, 232 output from a TU will be 
low-speed baudot, so this should have a second 232 port, since it is 
handled differently in the micro.  Hmm, a logical extension of this is to 
connect two tty machines at different speeds, so I am going to add a second 
HV loop as well.  And the low-volt loop might as well get a duplex switch 
as well.  So what we have then, are five different "ports," that connect to 
different types of hardware.  An optional micro can sit in the middle of 
everything, and provide interconnection and conversion, or you can simply 
jumper port-to-port directly.  You only need to populate the board for the 
ports you need (eg: just 232 and one loop).  The five ports are:

- PC-232:  a high-speed 232 port for a PC, with a DB9-F jack
     -ascii-only with 8/N/1/XON required, programmable for 
9600/19200/38400-baud

- TU-232:  a low-speed 232 port for a TU such as a Dovetron, with screw 
terminals
     - programmable for 60/66/75/100-wpm baudot, or 110/300-baud ascii

- HV-LOOP-1:  an opto-isolated high-voltage (150V) tty loop with two 1/4" jacks
    - for M14/15/19/28...
    - switch-selectable for full- or half-duplex
    - programmable for 60/66/75/100-wpm baudot

- HV-LOOP-2:  an opto-isolated high-voltage (150V) tty loop with two 1/4" jacks
    - for M14/15/19/28...
    - switch-selectable for full- or half-duplex
    - programmable for 60/66/75/100-wpm baudot

- LV-LOOP:  an opto-isolated low-voltage (30V) tty loop with two 3.5mm 
(1/8") jacks
    - for M32/33...
    - switch-selectable for full- or half-duplex
    - programmable for 60/66/75/100-wpm baudot, or 110/300-baud ascii

It looks like the board will be about 8-inches wide by about 3-inches 
deep.  All connectors and the full/half-duplex switches will be on the rear 
of the board.  Connections to the four transformers (one for 5V, one for 
30V, and two for 150V) will be along the front of the board.  I envision 
this mounted in an aluminum box or rack chassis, with the board at the 
rear-center, and the transformers mounted in front of it.  The two HV loops 
are at the right and left sides of the board, so the power resistors and 
heatsinks will be on either side of the board.  Various status leds can be 
mounted on the board, or wired to front-panel led indicators.  I'm also 
thinking of adding connections to a small text lcd that will scroll along 
with the data stream.

Once again, you only need to build the sections you need.  You can simply 
jumper the sections together if speeds are the same, or you can add the 
optional micro.

There are a lot of features for the micro that don't need to be finalized 
at this point -- I am just wanting to get the hardware defined so I can get 
the board off to the pcb house.

Still time for changes.  All feedback appreciated.  I'd also like a rough 
head count of those who are interested in a board, full-kit, or partial kit.

thanks,

gil



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