
mereyes
Australia
Asked
— Edited
Hey guys,
I tried to use the original LED that comes with the WALL-E U-Command with the EZ-B, but the LED does not turn on (using digital ports).
Should the original LED work, or should I use another type of LED with the EZ-B?
LED Info
Tried LED both ways (polarity), but still not turning on. Maybe I have 2 faulty LEDs...?
They were working before pulling apart the WALL-E though.
Did you use the original LED for the eye on WALL-E?
Sometimes LEDs cannot self limit the current going through them and burn out when direct voltage is applied. Usually a 330 ohm or 220ohm resistor is needed to limit the current going through the LED to around 20mA for common 5mm LEDs.
EZ-B puts out 5V (TRUE) on each I/O pin, so using ohm's law Voltage = I(current) * Resistance 5V = 20mA * R
R = 5V/20mA = 250 ohms so the closest more common resistor values are 220 and 330 ohms. 330ohms is the safer value cause it limits the current going through the LED to 15mA. This resistor can be in series with the LED on either the anode (+) or cathode (-) of the LED.
Hope the mini-tutorial is useful
*Note: If you were to use Signal and +5, then you will need a resistor. And your LED would always be on.
It turned out to be both original LEDs were faulty (I must have blown them somehow).
Tested a LED I pulled from a LED torch & it works fine with the EZ-B.
Now that I need to get some new blue LEDs for WALL-E, was thinking of using "color changing LEDs" instead to simulate Wall-e's different moods.
Will the color changing LEDs work with the EZ-B?
You can easily blow an LED if you connect the power directly to +5 and GND without a resistor (even for a brief second while testing polarity). You do not need a resistor if you connect the LED directly to the EZ-B's DIGITAL I/O
That's exactly what I need so I'm getting one straight away instead of using the color changing LED.
The BlinkM has PWR - + & I2C d c pins, how do I connect the 2 d c pins to the EZ-B?
Just looked at the EZ-B manual & it mentions the I2C header onboard
I've noticed is that when changing the intensity of a led or animating for instance a light pulse, that
the leds will flicker excessivly every so often when the intensity is changed. Would using a resistor
reduce this flickering?
Hi, do you also experience flickering when changing the intensity of leds that are directly hooked up on the i/o ports?