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'[PIC] Sensors request for info'
>From my privious posts, you can all tell I'm a newbie. But as I anxious wait
for my new Pickit2 burner and shipment of a couple different PIC's from
Microchip I'm starting to think of projects.
So my question is, how many and what kind of environmental sensors are PIC
friendly? Like making a weather box. Check temp, humidity, temperature,
On my second and most important project. Are there any "pressure sensors"
that can be used with Pics? I'd really like to make a Chess board that could
detect piece movement and feed that into the computer for computer-vs-human
games. From a software point of view it's pretty simple. As long as I can
get x/y coordinate from a grid I'm ok, then send the resulting x,y
coordinates back. Figure I'll have LED's on x,y for the board. Then sensors
along X and Y for input. Just need to know what kind of sensors I can use.
Not as nice as pressure sensitive for all 64 squares. But capturing
file/rank is enough for a starter project :)
Any tips? Anyone do something similiar?
For the pressure sensors, there are many that are 3 wires (ground,
+5vdc, and signal out) with the signal out at 0 -5 VDC which matches the
PIC's typical ADC 0 -5 VDC input. Just quickly looking at Digikey, I
find some typical part numbers.:
Typically several small filter capacitors are required, but other wise
just hook the sensor directly. There are many other manufacturer's, just
go to the web page and search for pressure sensor, 5 volt output, and
your pressure range. There are ones that get down to the range of
barometers and altimeters. The other 2 routes are 1: a sensor with out
built in OP-AMP where you add the external OP-AMP, and 2: The single
wire connected to a serial port, but simplest is the direct connection.
Joshua Shriver wrote:
Joshua Shriver wrote:
Search the piclist. Several years ago (at least 2) they had a
discussion on just such a project. Being able to know which chess peice
was where on the board.
Joshua Shriver wrote:
I know just the ticket for that application.
Use reflective IR emitter/receivers at each chess square. Each chess
piece would have a reflective bottom.
When the piece is removed from the board it is sensed, then when it is
placed it is sensed again. From that,
it is easy to deduct what is happening on the board.
Digikey sells these devices, they need only a small hole about 3/16" in
How 'bout a small magnet in each base and hall sensor or cheap reed switch at
each position. No holes... AND, a thin steel strip on the side will hold the
captured pieces in one place.
Bob Axtell wrote:
>> On my second and most important project. Are there any
>> "pressure sensors"
>> that can be used with Pics? I'd really like to make a
>> Chess board that could
>> Not as nice as pressure sensitive for all 64 squares. But
>> file/rank is enough for a starter project :)
Hall sensors under each square and magnets in the pieces.
RFID in each piece.
Excite detectors one square at a time (maybe by row / column
powering and read each piece absolutely.
A version of this *could* be reasonably cheap.
Place excitation coil under each square row column
addressed. Each piece has a transmitter in it. Could be RF,
acoustic even IR.
Selected piece declares its ID to probably a single
Could have resonant coils in each piece and tune across
range per square till resonance found.
Dr Skip wrote:
These are even better! Halls use a lot of current, but its only 64 places...
> RFID in each piece.
> Excite detectors one square at a time (maybe by row / column
> powering and read each piece absolutely.
You don't need anything that complicated.
The pieces have fixed starting points.
Any piece that is lifted has only a few legal destinations.
Castling is the only time things get even slightly interesting.
Squak if someone puts a piece down where it can't legally get to.
>> RFID in each piece.
>> Excite detectors one square at a time (maybe by row /
>> powering and read each piece absolutely.
> You don't need anything that complicated.
> The pieces have fixed starting points.
> Any piece that is lifted has only a few legal
> Castling is the only time things get even slightly
> Squak if someone puts a piece down where it can't legally
> get to.
I agree that you don't NEED absolute position detection if
everything works "by the rules". And my suggested Hall
effect system works at that level.
But it would be "nice" if one could handle real life rather
than demanding that actions suit your limited reality. If
you ever knock over a piece (let alone pieces) or nudge one
enough off its square to create an anomalous situation, then
something which detects piece position absolutely would be
useful. Also, alas, more expensive and complex.
Alan B. Pearce
> On my second and most important project. Are there any "pressure sensors"
> that can be used with Pics? I'd really like to make a Chess board that
> detect piece movement and feed that into the computer for
Rather than pressure sensor I would be tempted to use capacitance sensors.
Microchip have a series of app notes on using a PIC for this, for keyboard
sensing. With chess pieces I would look at putting a metal shim in the base
to make a capacitance bridge.
Another technique is to use a transformer sensor. I have somewhere a copy of
an HP Journal where they did this for a keyboard, with each transformer
being a 2 turn primary and 2 turn secondary as PCB etch. The key had a metal
pad on the bottom that acted as a shorted turn when the key was pressed. It
didn't actually contact the PCB, just came close enough to affect the
Alan Pearce wrote:
>I have somewhere a copy of
>an HP Journal where they did this for a keyboard
As an aside, HP Journals are available on line as .PDFs here:
Be patient as the download rate is slooow!
victorf ATSIGN windreader DOT com**
Alan B. Pearce
>Alan Pearce wrote:
>>I have somewhere a copy of
>>an HP Journal where they did this for a keyboard
>As an aside, HP Journals are available on line as .PDFs here:
>Be patient as the download rate is slooow!
Oh, wow - seventh heaven indeed. The downloads don't appear to be that slow,
other sites I have been to are worse ...
Somehow the description of the 1700 series scopes as 'Power Thrifty &
Portable' doesn't seem to hack it now ... (May 1971).
Ahh, the first description of HP-IB what eventually became IEEE-488. (Oct
1972). Further refinements described in Jan 1975.
The first of the scientific pocket calculators - the HP-35 (June 1972) -
ahh the nostalgia ...
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