On Apr 29, 9:42 pm, Thad Smith <ThadSm...@acm.org> wrote:
> simon86 wrote:
> > Hi,
>
> > I am currently working on a university project that concerns the
> > functionality of an inductive loop sensor. While I understand its basic
> > functionality I am unsure how to use it with microcontroller.
>
> > We will be using the sensor to detect vehicles that are parked in a
> > parking spot.
>
> There are standard detectors that put out a logic signal, usually grounding
> an output line when a vehicle is detected. They are used as input for
> traffic light controllers. My understanding of them, though, is that the
> standard design is dynamic: they average the inductance over time to set a
> threshold. Typically they will "tune out" cars that set over them for many
> minutes. That might make the standard units unworkable if you want to
> detect when a vehicle leaves its spot.
>
> --
> Thad
Our design output a PWM signal based on impedance (mix of capacitance
and inductance). It works well as long as the Z distance is small
compared to the X,Y or radius. For example, I have seen detection
rings of 1.5 times the size of cars.
A few of them are at the intersection outside my house.
Reply by Thad Smith●April 30, 20082008-04-30
simon86 wrote:
> Hi,
>
> I am currently working on a university project that concerns the
> functionality of an inductive loop sensor. While I understand its basic
> functionality I am unsure how to use it with microcontroller.
>
> We will be using the sensor to detect vehicles that are parked in a
> parking spot.
There are standard detectors that put out a logic signal, usually grounding
an output line when a vehicle is detected. They are used as input for
traffic light controllers. My understanding of them, though, is that the
standard design is dynamic: they average the inductance over time to set a
threshold. Typically they will "tune out" cars that set over them for many
minutes. That might make the standard units unworkable if you want to
detect when a vehicle leaves its spot.
--
Thad
Reply by Neil●April 30, 20082008-04-30
simon86 wrote:
> Hi,
>
> I am currently working on a university project that concerns the
> functionality of an inductive loop sensor. While I understand its basic
> functionality I am unsure how to use it with microcontroller.
>
> We will be using the sensor to detect vehicles that are parked in a
> parking spot. Once detected, we want the sensor to communicate with some
> sort of microcontroller so a timer can be set. How to actually connect the
> sensor and microcontroller is where we are facing difficulties at the
> moment. If you could provide information on how this could be done that
> would be highly appreciated.
>
> Also, what microcontroller has the following specifications:
> - Has one or more timers
> - is able to have an RF transciever connected to it
> - can be connected to an inductive loop sensor
>
> Thanks
>
>
Most Microcontrollers have timers Usually more than one.
There are many types RF transceivers many are serial and can connect to
any Microcontroller. Others are part of the chip.
To work with a microcontroller your loop sensor must out put a signal.
A voltage that can be measured or a pulse that can be timed. Assuming
it does not just output a Car / No Car signal.
Reply by linnix●April 29, 20082008-04-29
On Apr 29, 11:48 am, "simon86" <simo...@optushome.com.au> wrote:
> Hi,
>
> I am currently working on a university project that concerns the
> functionality of an inductive loop sensor. While I understand its basic
> functionality I am unsure how to use it with microcontroller.
>
> We will be using the sensor to detect vehicles that are parked in a
> parking spot. Once detected, we want the sensor to communicate with some
> sort of microcontroller so a timer can be set. How to actually connect the
> sensor and microcontroller is where we are facing difficulties at the
> moment. If you could provide information on how this could be done that
> would be highly appreciated.
>
> Also, what microcontroller has the following specifications:
> - Has one or more timers
> - is able to have an RF transciever connected to it
> - can be connected to an inductive loop sensor
>
> Thanks
Interesting, we did an experiment of exactly what you are considering,
only at a smaller scale. We made a loop of resistors, which has
capacitances and inductances as well. Let call it impedance
detection. With a detection loop of radius R, we found about 10%
change in impedence with 1R and 80% in 0R. Bascially, you are limited
to roughly 1R above the planer circle.
http://linnix.com/proto/fig1.jpg show relative frequency of no object
http://linnix.com/proto/fig2.jpg show object at 1R
http://linnix.com/proto/fig3.jpg show object at 0R
Reply by Richard Seriani●April 29, 20082008-04-29
"simon86" <simon86@optushome.com.au> wrote in message
news:jOadnf5aLdv98IrVnZ2dnUVZ_oGjnZ2d@giganews.com...
> Hi,
>
> I am currently working on a university project that concerns the
> functionality of an inductive loop sensor. While I understand its basic
> functionality I am unsure how to use it with microcontroller.
>
> We will be using the sensor to detect vehicles that are parked in a
> parking spot. Once detected, we want the sensor to communicate with some
> sort of microcontroller so a timer can be set. How to actually connect the
> sensor and microcontroller is where we are facing difficulties at the
> moment. If you could provide information on how this could be done that
> would be highly appreciated.
>
> Also, what microcontroller has the following specifications:
> - Has one or more timers
> - is able to have an RF transciever connected to it
> - can be connected to an inductive loop sensor
>
> Thanks
>
Simon86,
If I understand your question, the only part of the proposed project you
presently have any knowledge of is the basic functionality of the loop
sensor. If this is true, you should seriously consider becoming involved in
a different project unless you have a several months from concept to
completion. However, I may have misread your post.
As for your question about which microcontroller has the specs you listed,
which microcontrollers have you studied in your courses? It would be much
easier (faster) to start with one you know. It is very likely that one from
that (or those) manufacturer(s) would meet your needs. Check the
manufacturer's web site of the ones you are familiar with for a search
engine that will allow you to select based on desired capabilities. Your
project is unlikely to succeed if you have no knowledge of microcontrollers
unless you have time to learn everything you need to know about a particular
(or any) MCU.
You would need to provide more specifics in order to get much help:
What is it you don't understand about connecting the loop sensor to the MCU?
Is it the hardware required to convert the loop sensor output to something
the MCU can use? Is it the software to make that signal start a timer?
What type/lenght of timer do you need and what part of implementing this in
an MCU do you not understand?
What part does the RF transceiver play and what part of its implementation
do you not understand?
Basically, what have you done so far and exactly what is it you are having
problems with? There are several solutions to most problems and it wouldn't
be much use for someone to provide you a suggestion without knowing your
capabilities and what you have already tried (successfully or
unsuccessfully).
If all you are looking for is a complete solution with little effort, you
may have come to the wrong place. If you have already done some of the
groundwork and have specific questions about a particular issue, there are
many folks in this group who will be willing to help.
Good luck,
Richard
Reply by simon86●April 29, 20082008-04-29
Hi,
I am currently working on a university project that concerns the
functionality of an inductive loop sensor. While I understand its basic
functionality I am unsure how to use it with microcontroller.
We will be using the sensor to detect vehicles that are parked in a
parking spot. Once detected, we want the sensor to communicate with some
sort of microcontroller so a timer can be set. How to actually connect the
sensor and microcontroller is where we are facing difficulties at the
moment. If you could provide information on how this could be done that
would be highly appreciated.
Also, what microcontroller has the following specifications:
- Has one or more timers
- is able to have an RF transciever connected to it
- can be connected to an inductive loop sensor
Thanks