Ok I forgot how limited these devices were. The crystal divider is going to be external to the S1883. So there's some logic that changes the divide by for the clock and the bits and parity settings when the baud rates switch is moved.
You'd need to figure out how to load a different divisor into the BRG register. I haven't followed the details that closely, but one of the questions I had was does it need to be powered down after changing setting or did it turn out to have some sort of processor? If it's getting the setting out of a ROM, the 45.45 stuff might be able n it but not used.
Thinking about my suggestion, it would probably adversely affect the 110 baud rate which you may want to preserve. It might be possible to re-strap the uart for 45 baud if you are able to find any documentation on the chip.
Yeah I hooked it up to a 5v loop and logic analyzer last night, and sure enough 50 baud is EXACTLY 50 baud. It sends baudot for the first two and ASCII for 110 baud. Seems like it works!
Maybe try adjusting your range finder? Front panel says 50 baud not 45 baud?
Sent from Nine
From: Jeff G <[email protected]> Sent: Tuesday, January 24, 2023 9:26 PM To: Daniel Jones Cc:[email protected] Subject: Re: [GreenKeys] Navy Teletype Message Generator
Nothin wrong with spitballing - I'm going to take it back out to the garage and fiddle a bit. One thing I was trying was I had piped a signal gen through it and to a speaker, and had Fldigi listening via a webcam, but it couldn't decipher,
even putting it mark only mode. I'm going to see if my logic analyzer can record serial data. I also have one of those old Robot RTTY keyboards, not sure if that had a loop jack on it but I may pulling that out and see.
Jeff
On Tue, Jan 24, 2023 at 8:51 PM Daniel Jones <[email protected]> wrote:
I probably should have thought about it a little more before I sent the last message. It’s outputting a loop current it sounds like and not audio to be converted.
Don’t mind me while I go to the back of the room. Hi hi.
Unfortunately the VOLPE board can't make heads or tails of it either, no matter what baud or mode I use. Either the baud rate is wrong or I dunno what. In 45 baud mode, it prints gibberish similar but not identical to what the machine prints.
I may have to take it back out to the garage and fire up the logic analyzer lol. Then I can also check to see the ASCII/BAUDOT pin on the MM rom to see what mode its actually using.
5815 maps to Federal Supply Classification (FSC) 5815 = Teletype and Facsimile Equipment.
Google hasn't made any sense out of the other numbers yet.
Wayne
WB4OGM
-----Original Message-----
From: Jeffrey Golas <[email protected]>
To: Greenkeys <[email protected]>
Sent: Tue, Jan 24, 2023 7:40 am
Subject: [GreenKeys] Navy Teletype Message Generator
Thought you guys and gals might find this interesting...I volunteer on Battleship NJ and found this tucked away. Appears to be Navy-like but mentions "project" on
it, serial #3 lol. Other than WMS on the board theres no manufacturer.
Its a RTTY/Teletype message generator that does the "quick brown fox" message. Whats really interesting is that all that is based on ONE chip whose sole purpose is
exactly that. A MM5220DF. Other chips in that series have similar purposes, like ASCII-BAUDOT conversion.
Theres what looks like a white CPU, but Icant find any docs on it. It almost looks like something they had a surplus of, and with no rom, possibly wired it as a NOP
(no-operation) so that it would just be an 8 bit counter. I think anyway.
It does seen to work after cleaning all the switches, I plan to test on the loop. All it does is keying via a solid state relay. I tried piping my signal gen through
it but Fldigi couldnt decode.