On Sun, 29 Sep 2002, Dimitris Papavasileiou wrote:

> 1)Can the built-in UART deal with a reliable RF link (that is

Not in my experience.

> 2)What other things should I look out for?Like using Manchester code or not(I
> assume this is necessary as some transmission might include long 1 or 0
> strings which would result in clock drift),how the physical link should be
> established(FM RF,RF modem chip),etc.

I had to go with Manchester on the project I'm currently working on.
This of course pretty much rules out using the hardware UART.

Transmitting is easy, receiving much much less so.  I finally implemented
an interrupt driven tx/rx service routine that does both quite well, but
unfortunately I can't share the code as it was done on someone else's
nickel.  I can, however, tell you that a Microchip app note on Manchester
data exchange came in VERY handy.  It's not a PIC app note, it's a Keeloq
app note.

> 3)Out of curiosity.If all the above is possible and doesn't cost a fortune(it
> shouldn't) why do all commercial remote controls(RC cars etc.) use one analog
> channel per 'stick' instead of just reading a bunch of data with an MC and
> send it as digital data packets(like I want to do).It would give you as many
> channels as you can use with a 9600kbps link.

Well, I believe it's probably partly that they use dirt cheap application
specific chips dedicated for that purpose.  They also don't *need* to send
anything complicated, just very simple position information for X number
of channels.  Just a guess, but when designing for low-buck mass
production, cool counts for zero and cheap counts for everything.

Dale

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads