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NeoPixel Ring - 16 Christmas Ornament Battery Powered — Parallax Forums

NeoPixel Ring - 16 Christmas Ornament Battery Powered

JohnR2010JohnR2010 Posts: 431
edited 2014-09-30 12:13 in General Discussion
Building on JonnyMac's PASM and David Betz's Christmas ornament from last year I would like to make a battery powered version that will hang from my wife's candy canes she lines our driveway with. My plan is to use this project to get me up to speed on making a battery powered ZigBee device.

I'm working on my power budget and right off the bat I have a challenge I was wondering if anyone has a quick solution . I'm using Adafruit's NeoPixel 16x ring for my ornament it has 16 LEDs daisy chained with the WS2812 constant current addressable chip. When all the LEDs are off and I'm not sending any commands to the LEDs (Johnny's driver is stopped) the ring still pulls 15ma on the 5v VCC pin. This will kill my batteries in about a week my goal is 3 months of run time. Is there an off command I need to send? Johnny's driver sends out a block of memory values that represent a 24bit RGB color value for each of the 16 LEDs. To turn them all off I set all memory locations to 0x00 and stop the cog running the PASM at this point the ring is still pulling 15ma. Is there something I'm missing?

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-09-29 09:11
    What board are you using? What does your board do while "resting". If you can use a waitpxx or waitcnt in the single running cog, you can save more power.

    You can also switch your clock speed to RCSLOW when the Prop is in rest mode.

    Do you have a power LED on the board? These can pull a few mA.
  • JohnR2010JohnR2010 Posts: 431
    edited 2014-09-29 09:30
    The board I'm using is the Mini and the power for it Is not a problem I have it down to .014mA with slow clock and setting all the unused pins to output and high. The 15mA I'm asking about is being delivered directly to the NeoPixel's 5v VCC in pin.

    Thanks Duane
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-09-29 09:34
    JohnR2010 wrote: »
    The board I'm using is the Mini and the power for it Is not a problem I have it down to .014mA with slow clock and setting all the unused pins to output and high. The 15mA I'm asking about is being delivered directly to the NeoPixel's 5v VCC in pin.

    Thanks Duane

    Then it seem like you need a relay (or transistor of some sort) to turn the Neopixels on and off.

    Unless, there's a way to put the WS2811 chip in a sleep mode. Have you checked the datasheet?
  • JohnR2010JohnR2010 Posts: 431
    edited 2014-09-29 10:13
    Duane Degn wrote: »
    . Have you checked the datasheet?

    I have checked the data sheet http://www.adafruit.com/datasheets/WS2812.pdf and not seeing anything on a command for sleep. It just appears to be the colors are settable. I think I have some old power transistors laying around I just wanted to check and see if anyone else had a trick before I went down that route.

    Thanks.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-09-29 10:25
    JohnR2010 wrote: »
    I have checked the data sheet http://www.adafruit.com/datasheets/WS2812.pdf and not seeing anything on a command for sleep. It just appears to be the colors are settable. I think I have some old power transistors laying around I just wanted to check and see if anyone else had a trick before I went down that route.

    Thanks.

    I think you'll want to find the WS2811 datasheet for more information about the IC used to control the LEDs.

    Nope. It doesn't provide any sleep info.
  • TubularTubular Posts: 4,702
    edited 2014-09-29 15:39
    The logic in ws2811 chip consumes about 1ma quiescent each, so 15mA is about right for a 16 WS2812 ring. This is just the "logic", consumed even with leds off.

    Its a function of supply voltage so you can get it down to around 0.5mA per ws281x, and still have led operation (though blue and green are dimmer) down towards 3v.

    Using a P-fet to switch the supply is a good option. Or for small numbers of leds (less than 8 or so) you can use the prop output pins to switch, so long as you accept a lower brightness. There's some more info in my blog post (click under my avatar)
  • JonnyMacJonnyMac Posts: 9,105
    edited 2014-09-30 05:32
    You might consider powering the LED string with a p-channel FET. (Edit: I see Lachlan suggested that).

    You can also put the Propeller into very low-power mode when not animating LEDs (see the DEFCON badge code)

    My name is Jon. Not John, Jonny, or Johnny. Jon. J. O. N. (see my signature) :)
  • NWCCTVNWCCTV Posts: 3,629
    edited 2014-09-30 12:13
    My name is Jon. Not John, Jonny, or Johnny.
    I guess that is confusing since your username is JonnyMac.
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