[GreenKeys] USB-teletype adapters (update #2)

[epvgk at limpoc.com]

On Sat, May 07, 2016 at 10:41:38AM -0500, Chris Elmquist wrote:
> 
> I would never judge your code!  You _actually_ did something I've only been
> thinking about for years.
> 
> Some other folks asked about a serial to serial converter similar to this
> and I did do one of those a few years ago using an ATTiny2313 but it is not
> a production solution.  It's a one off, wired on Vector board and built into
> one of the BlackBox RS232 to current loop converters.   I use it to
> change baud rate for my M33s and manage flow control with RTS/CTS on
> the 9600 baud side.

I was thinking that one of these adapters plugged into a raspberry pi type thing
would be a reasonable solution for that. You could let the adapter handle the
loop signalling and character set stuff and linux could just copy serial back
and forth to/from a USB rs232 serial port. Plus you'd have the option of throwing
on a couple of pushbuttons and being able to print canned printouts on demand 
from a flash card or USB drive. 


> > It's a 32u2 and it's only half full. 
> 
> We should be able to fit a TCP stack and web server in there then ;-)

I have another project that does have that on a 328. It was a matter of principle
at the time, and it worked, but it ended up with having three bytes of flash free. :) 
(It sampled a bunch of ADC channels to measure AC current, did the math to compute 
RMS value, and sent the readings to a graphing server via UDP and allowed queries
and reconfiguration via web)

I also have a fully digital implementation of the RTTY demodulator that runs on avr,
but the adc doesn't have enough dynamic range for it to work very well without being
fiddly... 

eric


> 
> Chris N?JCF
> -- 
> Chris Elmquist