DIY telemetry ... Re: [Diy_efi] tiny injection

[Jon V]

Many of the PICs have A/D converters built in. Last I checked, the 12c67x
was the smallest (they are 8-pin packs with two analog inputs, 128B ram,
and space for 1 or 2 K commands), and they are also some of the easiest
and most fun microcontrollers around, IMO. Built-in oscillator so you just
hook them up to power and they go. And they are TINY (especially the
surface mount OTP versions) and they use very little power, so you could
have them on an RC model (including a small electric stik plane) without
any difficulty.  Very easy to program. PIC assembler is a snap (30
commands or so), and I guess there are other development environments
available for them (I've only used the assembler).  The larger PICs have
more inputs, but often aren't so easy to use (some require external
clocking, etcetera).

There are other ucs with A/D out there, but I sort of inherited a stack
of PIC stuff from a job I was doing and I've never had an excuse to do
other research, so you'll have to find'em on your own.


What sort of range are you looking for? Line of sight only, or do you want
some penetration? There are a few companies that make adapters for RS-232
over 800mhz s.s. Last I checked, Inyo Media was one (the cheapest), and I
can't remember the others but they are available. Some are fairly small,
but you'd probably be better off with a purpose-built telemetry
transmitter.

At the high end, I've often considered searching for a fancy PDA (e.g.
ipaq, zaurus, etcetera) someone sat on and broke the display/backlight,
and using 802.11 for the radio link. It has a fairly good line-of-sight
range, and the PDA CPUs are more than capable of doing anything you want,
they have plenty of ram for data caps. Only downside is that they are
heavy...a couple of ounces at least...and they suck power.

-- 
Jon
---
A man of genius makes no mistakes.
His errors are volitional and are the portals of discovery.
                -- James Joyce, "Ulysses"




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