Gemma M0 shuts off

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colleen110
 
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Gemma M0 shuts off

Post by colleen110 »

I have a Gemma M0 connecting to two 20 NeoPixel strands (A1 -> DIN, VOUT -> 5V) and a NeoPixel jewel (A2 -> DIN, VOUT -> 5V). All the ground wires are connected.
I was able to run my code compiled on Arduino, turning all NeoPixels on and do some effects.. But after running for about 5 minutes it just goes off. Powered either by USB through my laptop or "Lithium Ion Battery - 3.7V 2000mAh". After that it just won't turn on for a while. What could be the issue here?
First I thought maybe the strands are drawing too much power but I see several projects with similar or more amount of NeoPixels. https://learn.adafruit.com/animated-neo ... /materials
Please help!
Gemma M0 https://learn.adafruit.com/assets/49776
20 NeoPixel strands https://www.adafruit.com/product/3630

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dastels
 
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Re: Gemma M0 shuts off

Post by dastels »

It could be a current demand issue. The amount of current required by NeoPixels depends on how much light they are producing, not just the number of pixels. If it's set to full brightness white, a pixel will draw 60mA, full brightness red, green, or blue would be 20mA. lower brightness takes less current.

Try lowering brightness of having fewer pixels on. See https://learn.adafruit.com/sipping-power-with-neopixels for more tips on lowering current requirements.

You might have trouble when the Gemma is powered through the USB: the NeoPixels are bing powered with 5v, but the data signal is 3.3v. The power and data should be the same voltage. In this case that means powering the NeoPixels with 3.3v, or using a level shifter to boost the 3.3v signal to the same level as the pixels are being powered with. See https://learn.adafruit.com/neopixel-levelshifter

And in general read through https://learn.adafruit.com/adafruit-neopixel-uberguide if you haven't.

Dave

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colleen110
 
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Re: Gemma M0 shuts off

Post by colleen110 »

Interesting. All the tutorial projects I see connect them to VOUT (5v) pad. Glad I know that now.
I have disconnected the strands so now I just have one NeoPixel on it, but Gemma M0 itself doesn't even turn on so I'm not able even upload the code to tone down the brightness. Have I busted my M0? Luckily I have another one so I'll redo this tonight connecting to 3.3v pad...wish me luck!
Thanks Dave.

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dastels
 
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Re: Gemma M0 shuts off

Post by dastels »

Vout is either 5v from the USB or the battery voltage, whichever is higher. The result is that it's the battery if USB is not connected, and 5v if it is. Have you tried a different USB port on your computer. USB hardware will often disable ports that try to draw too much current. If that's the case, powering off & on the computer will re-enable the port.

Dave

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colleen110
 
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Re: Gemma M0 shuts off

Post by colleen110 »

Hmm I switched to another USB port, it turned on for 5 seconds and then went off. I restarted the computer and now both ports not turning it on. Is is indeed giving me the message "Unplug the accessory using too much power to re-enable USB devices". But I only have an NeoPixel Jewel (7 LEDs) connected to M0 now.

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dastels
 
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Re: Gemma M0 shuts off

Post by dastels »

What colour are you setting the jewel to? If all 7 pixels are on bright white the jewel will take 0.42A all by itself and most (iirc) USB ports can provide 0.5A. Try without the jewel or with all 7 NeoPixels set to (0, 0, 0) i.e. 0x000000 i.e. off.

Dave

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colleen110
 
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Re: Gemma M0 shuts off

Post by colleen110 »

Ok looks like Jewel was indeed the problem! Removed the Jewel and it's turning on. I've been setting 6 LEDs on the Jewel to white with brightness 20 out of 255.

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dastels
 
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Re: Gemma M0 shuts off

Post by dastels »

Hmm. NeoPixels are hungry little things. I would think that wouldn't be drawing too much power, but I have no idea what the library and NeoPixel controller chip does with the numbers you send it in terms of mapping it to a PWM duty cycle for the LED.

If you're going to use strands of any length it looks like you'll need a separate power supply. One that plugs into the wall if possible. Again, https://learn.adafruit.com/adafruit-neopixel-uberguide has l;oads of information on powering them.

Dave

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colleen110
 
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Re: Gemma M0 shuts off

Post by colleen110 »

Yeah I'm changing my design to not use white...Thank you so much for your help Dave!

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dastels
 
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Re: Gemma M0 shuts off

Post by dastels »

You're welcome.

Dave

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