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[aprssig] Replacement binaries for UIDIGI ? (stand-alone digi software)

Scott Miller scott at opentrac.org
Sat Feb 28 19:12:47 UTC 2009

> What Scott, you don't have fond memories of Z80 assembly?  I (re)wrote a whole
> kermit protocol implementation and UI in Z80 assembly in the 80s...  Does
> that date me :-)  You are absolutely right though, you can put a much more 

Despite its register limitations, I'll still take 6800 over Z80 any day. 
  Never done Kermit... I did squeeze an XMODEM implementation into the 
T2's bootloader in HC08 assembly, though.  That's the cross-platform 
firmware update mechanism.

> powerful processor on board that device in a smaller package and get some real 
> work done.  You could even spend some time to make it something that others 
> could assemble and use!

To some degree.  A 32-pin QFP will fit in a .6" footprint with room for 
the leads and traces.  You're going to need 24 pins for the address and 
data bus lines, though, plus control lines and whatever I/Os are needed. 
  Beyond 32 pins I think you'd have to go to a QFN or BGA package or 
something.  Unless you make the board larger and just have it hang over 
the side, anyway.  Or use surface mount pins on the bottom for the 
socket connection, but those would be a pain to install.  Edge-mount 
pins like on the Basic Stamp might free up a few mils compared to SIP 
headers.  Hmm.. yeah, that way you could probably squeeze a 64-pin or 
44-pin LQFP on there.  You can solder that by hand.

Fun stuff.  If I had time, I'd take a crack at it myself.  The T2's code 
could be adapted to use the external RAM for the packet buffers... I 
think that'd be the hardest part.  Most MCUs you're going to cram onto a 
board like that aren't going to have an external data bus, so the 
external RAM wouldn't be mapped into the MCU's address space, but modern 
MCUs are fast enough that it wouldn't matter that much.

For some reason I've only got sheet 2 of the MFJ 1270B's schematic. 
Anyone got a complete TNC2 schematic for reference?


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