NeoPixel Current

blittled2

I am planning on using 2 NeoPixel rings with 12 NeoPixels each on a Propeller Robot Control Board (#28230) and was wondering if that is too large a current draw on two separate output pins?

Duane Degn

Your NeoPixels should be fine on that board. The 5V regulator is rated at 3 amps according to the datasheet.

blittled2

Thanks, Duane, I saw that a Propeller Pin could only handle 50mA when in worse case the ring needs 250mA. Then after reading your reply I realized that the 50mA is input current, output current is limited to the current that is powering the board and like you said is up to 3 AMPS which is plenty. I don't think my brain is getting enough current either today

Duane Degn

Just in case it's still not clear, the current from or to a Propeller I/O pin should be limited to about 20mA (I'm not positive that's the exact limit but it's close).
One advantage NeoPixels have, is they're not powered from the I/O pin. The I/O pin just sends data to the NeoPixels to tell it which colors to display. The power to the LEDs come from the 5V power line.
In a way, NeoPixels are comparable to servos. The data line on a servo isn't powering the motor, just like the data line on NeoPixels isn't powering the LEDs.
That board should work particularly well with NeoPixels. I've had many NeoPixels which don't work will with 3.3V logic. The board you have shifts the logic up to 5V so the NeoPixels should behave well.

JonnyMac

I always budget 60mA per pixel and then goose the total by 50%. Remember, the IO pins are not powering the pixels, there is nearly no load on the signal pin. The current is pulled from your 5v supply.

blittled2

Thanks for the clarification. I have quite a few Propeller boards and like you said I picked that one due to the level shifters on the pins

JonnyMac

If the distance between the Propeller and the first pixel is short, a level shifter is usually not required. In my pro work, I use a TT4427 as a level shifter because it provides a very stiff output which ensures a good signal across a long line to the pixels.