Well, CRC16 is a great link check and can be easily implemented with a
minimum cpu overhead. A PC-DOS program to transfer and receive files is
something quite easier to produce, except if you want to go for root
directories and tree structures...yack!... The ready made IrDA links for
PC is not so expensive and the hardware control is just somehow an
UART.  You can also implement your own IrDA hardware, a simple TOIM3232,
xtal 3.57MHz + TFDS3000 from Temic and a couple of resistors, this is
everything you need, well, you need to connect it to an UART, and it is
ttl level, so you would need a MAX232 or brute force with a 74HCT04...
it works and works well.  I use something like that to program/test a
portable device we have with IrDA.  This set could less than $20.00, I
don't know how much cost the ready made IrDA for PC's...
Wagner

Mark Willis wrote:
>
> Has anyone implemented ZModem on a PIC yet?  At least XModem or
> YModem?
>
>   Something where you just use the IrDA port as a serial "wired" link
> works just fine between my various laptops (Heck, I just use InterLink &
> InterServer!)  I do "Zip" files up so I can tell if I get an error,
> because not everything transmits over correctly - on occasion.  Really
> handy for my one laptop that doesn't have a floppy yet & which I haven't
> gotten PCMCIA Card & Socket Services installed into yet (Need to install
> Windows first.  GRRR.  Don't get me started.  <G>)
>
>   Seems to me you could try to treat this as a somewhat "noisy", wired
> connection, as that's what I've been able to do with it here, make some
> kind of half-smart protocol where the PIC occasionally pings the PC and
> only if the PC responds does the PIC try to establish a link, and then
> ZModem exchange your information.  {Half duplex is probably a better
> idea than full duplex <G>}  Error checking and NAKing is easy enough...
> I've done that often enough in Dos that I'd use Dos (I've done it in
> Windows, too, but the Dos app's just LOTS easier to do, more reliable,
> and far smaller - you can get a PC110 or the like and multi-boot it to
> Dos easily enough.  Use Windows if you prefer, just stating MY
> preference <G>)
>
>   Mark