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Wed 2018.08.22
Hello @Marty_McFly,
re: 'I know that they use about 1 mah when turned off'
Dr Emmett Brown here, . . . . It's more like 1.21 gigawatts? Great Scott!
ref: youtube.com/watch?v=I5cYgRnfFDA
Would you provide a link to the datasheet you got that factoid from please. Which chip are you using?I'm not seeing that 1mAh detail for the WS2812
https://cdn-shop.adafruit.com/datasheets/WS2812.pdf
SK6812
https://cdn-shop.adafruit.com/product-files/1138/SK6812+LED+datasheet+.pdf
Now on to how the project will power the Neopixel:re: 'so if I connect the neopixel's power to an IO pin'
I'd be really concerned with the microcontroller GPIO pin:
See: http://www.espruino.com/datasheets/STM32F401xD.pdf
p.59
Each GPIO pin can source or sink only 25ma
Total max all pins is 120maSo, out of luck that way, unless you use the GPIO pin to control a transistor to turn on that power. A standard 2n2222 should do.
Incidentally, I'm against sourcing power using three GPIO pins tied together. Why risk frying a $30 microcontroller, for the sake of a $0.25 part? Turn off current can wreak havoc as the AdaFruit Uber Neopixel pdf indicates.
Inexpensive way
http://web.mit.edu/6.101/www/reference/2N2222A.pdfExpensive way using a relay
Also remember the Neopixel will draw ~60mA when producing white.See this forum post WS2812B issues from a week ago:
http://forum.espruino.com/conversations/324269/#comment14372431So, what is the plan to power the insert name of espruino controller for your single neopixel project. A stand alone battery operated demo maybe?
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Robin
Hey y'all,
I'm thinking of using a neopixel in my project and I know that they use about 1 mah when turned off by the controller chip. I'm only going to use a single pixel anyways, so if I connect the neopixel's power to an IO pin and only provide power when I'm actually going to use it, will I be able to save the 1mah and thus improve battery life?
Thanks! :)