Re: TI-H: RF link
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Re: TI-H: RF link
From: "Simon Trimble" <gingerno1@hotmail.com>
> I think the best way is to you a uC and those ready-built 433Mhz modules
> that only cost a few and can transmit around 40m.
I agree, I found several different versions, varying in price from
$20 to about $120. The capabilities were about in line with the price.
The most expensive version was basicly transparent to serial data and
would make implimenting a link almost trivial.
As usual with TI hardware, most people would rather spend less at
the cost of complicating the hardware :)
Often people will tell you that the ~433 band is not usable
because its too busy, however I have not found this to be
true. If you desire long range it would probably be a problem,
but for short range communications it should work just fine.
Radio solutions for longer range (over about 10-20m) tend
to get expensive, but you do tend to get what you pay for.
> Emulating a direct link-cable connection would be best i think in that
> hardly any software would need to be written (can be done in basic if
needed
> too) and it would be compatible with 'all' (prove me wrong) TI calcs.
IMO, the best mode of operation would be for the module
to communicate the state of the link port lines. This
would allow compatibility with any link port protocol.
However, allowing the microcontroller to cache and transmit
packetized data (say 5-10 bytes at a time) would be likely
to be faster.
> PS. The radio link cable that ive see on the net so far is quite
> complicated and uses IC's that ive never seen before. Perhaps a
> link cable that uses well-known components and IC's (perhaps a
> PIC microcontroller, coz most elctronics enthusiasts have the
> facilites to program them. If not they only
> cost a few $ to buy ready-programmed).
For the most rapid application development time, I'd suggest the
use of the 28.8 Ricochet Wireless Modems, which really do have a
pretty good cost-performance ratio, but have now been discontinued
by the manufacturer. The new Ricochet 128's do NOT do peer-to-peer
connections, as the 28.8's do.
Heres one.
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=473103446
And a reality check.
http://slashdot.org/articles/00/05/23/1311203.shtml
Of course, for what I'd consider the BEST wireless link, you'd have
to interface the microcontroller (AVR preferably) to the address
lines inside the calc, and keep the entire thing internal. :)
DK