I'm looking for the simplest way to add a proximity detector that
detects when something moves in front of it, at a range of ~ 1meter -
no info on distance is necessary, just on/off.
Can you point me to some resource - possibly DIY? I only found until
now the Sharp GP2D12, but I'd prefer a slightly larger range.
The Sharp has a range of a few millimenters to 1.3 meters -- seems to
fit the bill according to your specs.
In any case there are versions with longer ranges. look at the
GP2Y0A02YK. It has limited close-range sensitivity, but a maximum of
about 2.5 meters.
You will find the LM565 ? PLL to be the lowest
cost and highest performance device .
Its antenna pattern is distorted by objects
and the rate is readable .
Since its a PhaseLockedLoop , it will
read rate as well as the pull .
You can gaurd them , so they will be able
to figure if the object is moving and how
fast and what direction .
There is less cost and hassle , using
LM565 . But of course you must use
an ARM 7 , 144 pin , to make it "sing"
I'm using them and a $20 700by420 pixel
BW CCD camera to control moving objects
like robots and cars . It has .01 LUX ( I.R.)
Im using front surface mirrors that rotate
in front of the camera , periodically to
expand the vu of the camera .
I will scan only every 10th vertical line
and evaluate it , as a insects compound
eye does . Then switch to full scan
to do slow stuff .
I2C and RS232 and SPI . Everyone thinks
they are narrow . But clever people can
make them work more .
You might try using SPI to do RS232
and vice versa , and SPI sub for I2C
etc etc ..
We read the specs , and get blinded ,
because spec sheets are poorly written
leave out stuff and amount to advertizing !
So we arent brave enuf to experiment .
I will be booting ARM by many methods .
I want flexibilty and fault tolerance ,
so when i want to boot it , i want
to be able to select many methods of
booting , at boot time .
The SPI bus is the lowest cost and
smartest method , just put a tiny 2K
EEPROM there .
If you boot wide , then you'll have to
configure EXT RAM . SPI is easier .
74HC595 and 597 is a generic way to
do parallel on SPI bus . HC299 also
I will use many ARM 7 mcu's to
do the work .
thank you for the GP2Y0A02YK. suggestion, I didnt know it and I guess
it will be OK.
Concerning the LM565, I confess I did not understand how to use it. If
you (werty) have a link to some schematics I'll be happy to study
ignore werty. in fact, ignore anyone whose name is a linear sequence
of characters on a standard keyboard. it is unlikely that you would
want to use a phase locked loop for this application.
sharp rangefinders work pretty well. i have used them on every robot
if you want to d.i.y, you could use an infrared led and detector as
available at radio shack. that, however, would be a luminance based
sensor, so a good reflector at much more than one meter range would
trigger it before a poor reflector at less than one meter. also, it
would have as wide beam pattern as the led, which is usually pretty
sharp rangefinders have an infrared led with a focus lens so they have
a pretty narrow beam width. also, they measure angle, not luminance,
so as long as there is minimum reflection they are unaffected by
Proximity detectors are electrostatic
and Piezio ( worthless ) .
Electrostatic have a long range .
But cost 1000 times more $$ .
LM565 has a cap and a coil , the coil
is the antenna , a big loop of wire .
Anything that has capacitive coupling
to the loop of wire , will pull the PLL .
So look at the DC voltage change
on VCO .
Its easy to experiment .
BTW I have been studying the ARM
Instruction set . Its a closely gaurded
Everyone wants you to see only nuemonics
and not the binary it refers to .
Ville Pietikainen of Finland , gave out
a free xxxx.PDF on Thumb , but it was
buggy . He does not understand the "H"
I've been searching for months , for
second sources on Thumb ISA .
Fortunetly , Edward Nevill
firstname.lastname@example.org has a more
accurate chart .
Its a struggle , cause they want to appear
a WIZARD , and show you how great their
assemblers are . Assemblers are WORSE !
They lock 2 doors !
They claim Psuedo ops . But its supposed
to be in a "macro" NOT a psuedo op !
Im doin ARM 7 and 9 .
I have boxes full of ARM mcu's .
Every door closed ! ATMEL created
some helpful tools to boot its AT91xxx .
Bloat crap , SAMBA is 20MB !
I will instead program a tiny 35KB Editor
"Qedit" to do the flashing .
All the I.D.E.'s and C/C++ compilers
are a huge waste of effort , in programming
MCU's for robots .
You can create s/w in minutes , with a
modern "loader" in 8 KB of the Flash RAM .
But exect the same Luddite Loaders
from all the big companys , ST , ATMEL,
Philips , all waste the 8KB , it will only
look in 2 places ! UART and USB ,
and then , expect deaf and dumb .
My loader starts in SRAM , so it can be
fixed , if it dont work , in minutes .
after weeks of coding , when you have
not needed to "improve" it , then flash
Always treat your flash as a HDD , and
use precious SRAM for hi-speed code .
The performanceof ARM 7 is slowed
by less SRAM .
I found 2 ARM7s with 64KB and 96KB
Your code running inside , will run very
fast and at extreme low power !
Im doin many things ,
ARM EVBs , Nintendo DS Lites ,
GP2X boxes , all ARM mcu's .
Very powerful !
In order to select the best rangefinder you will want to think about
what type of object you expect.
For instance, sonar should work for solid objects with large surfaces
that face your sensor, but not so well if they are at angles.
IR sensors also have strengths and weaknesses.
You can also use structured light.
And yes, there are electrical proximity sensors...
Best of luck!
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