Question about avr and leds as sensors : 8051 Microcontroller Projects AVR PIC Projects Tutorials Ebooks Libraries codes

Forums

8051 Microcontroller Projects AVR PIC Projects Tutorials Ebooks Libraries codes :: Forums :: Discuss and Learn :: AVR Discussion Forum		<< Previous thread \| Next thread >>
Question about avr and leds as sensors


Moderators: Ajay, Junied , abbas1707, Arun Kumar V, pdi33, Shailesh NAYAK, ۞ TPS ۞, shyam, sashijoseph

Author

Post

zatar

Mon Jun 09 2008, 07:01AM

Registered Member #8272

Joined: Thu Jun 05 2008, 05:39PM

Posts: 8
Thanked 0 times in 0 posts

Hi all,

I'm totally new to avr but because me and my teacher are working on the same project I should learn it a bit. So question 1 is: Does anyone know some good sites/ (e-)books?

A little bit on the project: We would like to build a miniature of a garage that shows how many parkings are free AND that guides you to a free parking by led arrows lighting your path.
A problem we have is how to detect the cars in a cheap way.

Therefore I would like to use a led as a sensor. Leds give up a small voltage when light drops in on them. I would like to test if it's possible to use a 2colour led with common cathode to make one half light up as lighting in the garage and one halve used as sensor. (if I'm not mistaking I need a ADC converter?)

Is there anyone who can help me get started with this? I would like to learn/use assembler since it is the die-hard way of programming

Also have an option 2 in mind by letting the led light up for a couple of µs or ms and then turn it of for a couple of µs/ms to measure. But that would truly be an option 2

Many thanks in advance !

sashijoseph

Tue Jun 10 2008, 12:11AM

Registered Member #5870

Joined: Mon Feb 04 2008, 06:26PM

Posts: 471
Thanked 106 times in 101 posts

Hi Zatar...
There's a nice tutorial right here in this site,which will quickly get you in business.Look here : http://www.8051projects.net/avr-microcontroller-tutorial.html

About your project; you can use an infrared led-infrared sensor pair for detecting cars.Wouldn't need an adc.
Using a normal led as a sensor could be tricky because different ambient light conditions could affect the accuracy.But with consistent light conditions and careful placement of the LED you could probably put it to use.
And yes you would need an adc to measure the small voltage generated by light falling on the led.
You could do sth. similar with an LDR as well.

Let there be music........