[GreenKeys] USB to Loop TTY Control Device

Thu Mar 14 12:32:11 EDT 2024

Yes, I would think so as well.

Steve G./N4TTY

From: eric <epvgk at limpoc.com> 
Sent: Thursday, March 14, 2024 12:18 PM
To: steve.n4tty at gmail.com
Cc: 'greenkeys' <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] USB to Loop TTY Control Device

I did, and more recently Jordan built a bunch more, but that's not to say someone shouldn't do an updated design with more modern features!

Harold's design is much more comprehensive, for instance - https://w6iwi.org/rtty/DspTU2/

In either case though, I'm afraid the bill of materials will be substantially more than $5.

eric

On 2024-03-14 08:45, steve.n4tty at gmail.com <mailto:steve.n4tty at gmail.com>  wrote:

Didn't Eric Volpe make this exact device several years ago?

Steve G./N4TTY

From: greenkeys-bounces at mailman.qth.net <mailto:greenkeys-bounces at mailman.qth.net>  <greenkeys-bounces at mailman.qth.net <mailto:greenkeys-bounces at mailman.qth.net> > On Behalf Of ad7i
Sent: Wednesday, March 13, 2024 8:17 PM
To: greenkeys <greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net> >
Subject: [GreenKeys] USB to Loop TTY Control Device

Greeting Greenkeyers --

I've been reading on this group about the discontinued manufacture and availability of USB to SERIAL (bridge) devices that can run 5 bit 45 baud data on the serial side.

I can't offer any alternative device suggestions that can do that USB-SERIAL bridge function natively like the older devices do, but I wanted to ask the group if anyone had an interest in a device that would accept USB Serial ASCII and the output would be a loop control switch (like an opto-coupler) that would key a loop with 5 unit TTY code, as controlled by the host PC?  It would be also possible for the host computer to send 5 unit code to the TTY by putting the device in mode where it only looks at the lowest 5 bits of the incoming ASCII code and then sends that 5 unit code to the TTY (which moves the responsibility of coding of FIGS and LTRS from the device to the host computer).  That type of functionality would *not* be compatible with existing PC or Linux code that drives one of the older USB-SERIAL devices that can run a 45 bps.  But if you had access to the source code it should be a straightforward task to modify that code to use the device I describe to drive a 5 unit TTY.  Control of the device (change mode from ASCII to BAUDOT or BAUDOT to ASCII, set bit rate (45, 50, 75, 100), disable/enable loop control inversion, etc. would be done through something like an escape character followed by two letters or numbers.  I'd propose to use the ASCII caret symbol (^,  0x5E) as the escape character.   So to set the loop baud rate to 45.45 bps the host computer would send ^45 (which would not print on the TTY).  To set the code to BAUDOT the host computer would send ^BA (which would not print on the TTY), etc.  The particular escape character and the two character command that followed could be most anything, as long the escape character is not a symbol that a TTY would print.  The device could also include functionality to send data from the TTY Keyboad loop to the host PC.

I think something like this device could be constructed for less than $5 in parts, including the PCB.  Power would be supplied to the device from the Host computer via the USB cable.

If this might be of interest to you please let me know and we can kick around the specifics of functionality and specifications.

73, Paul, ad7i

ad7i at ad7i.net <mailto:ad7i at ad7i.net> 

Middletown, NJ

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