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Topic: Getting the Teensy to recongize the LED's (Read 442 times) previous topic - next topic

regios287

My circuit is currently:

TEENSY 2.0 to RESISTOR to LED to GROUND

Im trying to make it so that if green led = flash once, if yellow = flash twice, if red, flash 3 times

How would I do this? Is there a function call to make the Teensy board recognize the LED's? Or the Resistance?

macegr

You might be able to do this by attempting to read the LED voltage using an ADC, but that may not tell you anything because LEDs are made using various chemistries. The only reliable way to do this would be to use a color sensor chip and aim it at the LED. You'll find that to be a much more expensive and complicated project.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

fungus

You could read the voltage between the resistor and the LED.

That would tell you the difference between red and green, detecting other colors might be difficult.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

cjdelphi

Each wavelength / band gap - has a certain forward voltage drop, so that's what you'd be measuring...  curious project I might have a play see what results i get...


regios287

Let's say Im using these LED's

Code: [Select]

http://www.digikey.com/product-detail/en/WP113SRDT/754-1202-ND/1747601
http://www.digikey.com/product-detail/en/WP113GDT/754-1200-ND/1747599
http://www.digikey.com/product-detail/en/WP113YDT/754-1203-ND/1747602


How would I write that in Arduino?

cjdelphi

wow, i've not seen one of them since 1988 lol, age 7 at the top of the stairs my dad gave me a 9v battery and an LED, thinking back the 9v battery was pretty dead (he got me to taste it, very very mild) but yeah i connected the LED both ways until it lit up glowed almost changing color (obviously, too much voltage) but as the battery went dead , the LED was this type!

digitalWrite(pin,HIGH);

use a 300 ohm resistor in series to keep the current down on these old things...

cjdelphi

oh yeah, you meant reading the voltage duh....

hook one up and measure the voltage....

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