Blink-O-Matic Code LED power supply

Hi, I have a SparkFun Electric Imp breakout board. I uploaded this code and I used one of my LED lying around my room. When I measured the current the board was producing 5mA… Since the suggested current is 16 - 18 mA and voltage is 1.8 to 2.2V I can’t power the LED…

Is there any other ways to power the LED to give the visual reference?

Many thanks

Can you clarify how you’ve got your parts connected and how you took your current measurement? It’s a little ambiguous right now.


…also, LEDs at 16-18mA will be incredibly bright, in general; as an example, I believe the red LED within the imp is driven at 2mA.

The GPIOs on the imp are not designed to directly drive bright LEDs - you’d need to add a transistor for that.

@tbuttner this is the setup…

I just got into the Arduino and Electric Imp developing a few days ago… So I don’t really know about the hardware developing…

Generally, you don’t just put an LED between power and an IO pin. You should always use a current limiting resistor (this is what gets the 3.3v down to the ~2v of the LED).

With a big old LED like that, and the limited drive of an imp pin, you may be ok though. One thing that’s not going to help you here: you have the LED the wrong way round. Flat side is negative (cathode) and should go to pin9, whereas the other side (anode) would go to 3v3. Worst case: LED is very bright then doesn’t work any more. You have been warned - really, 100 ohms in series with either leg would be best.

There is a nice series of arduino specific tutorials over here