Noob help needed - Teensy 3.1 and WS2812B Strip

[dotbat]

I just ordered my first Teensy 3.1 along with a 60 LED strip from Adafruit. I also picked up the 74AHCT125 that Adafruit had in stock and recommended to step up the logic to 5v. So far, I cannot get the LED strip to light at all. I have tried with and without the 74AHCT125 (some places said they might work without it, at least enough to test). I have tried using the strandtest with the adafruit neopixel as well as just changing a couple of pixels according to their code.




Okay... so in uploading this I realized I left off the ground on the LED logic. I know it isn't in this picture, but I know for a fact I tried it with the ground. I removed some excess components and wires before taking this picture and going to bed, so I must have accidentally removed it.

Some other details: the Teensy works fine otherwise in the current setup. I have separated the VIN and VUSB pads and power it only from a 5v/2A wall wart. I can write programs to make standard LEDs light, blink, etc. I know the LED strip is getting power because some of the LEDs flash when I plug in the barrel connector. The logic cables from the LED strip are snug in the bread board but I have also connected them more directly to test. I have also tested with and without the resistor on the logic cable. If it matters, I'm using the latest Arduino and Teensy software (downloaded last night) on my Mac. I may try it on my Windows computer tonight.

If we assume it doesn't work with the ground there, I have a few questions:

• Is there anything obviously wrong with my setup?
• Should I be able to use the 74AHCT125?
• Am I using the 74AHCT125 correctly?
• Is the Adafruit neopixel library what I should be using right now, or is there something better for troubleshooting?
• Should I be able to use these LEDs at all without the 74AHCT125 for testing purposes?
• What should my next steps be to troubleshoot this?
• Is there any functional difference running the Teensy and Arduino software on Mac vs Windows?

Thanks for bearing with me and my many questions. This is kind of a totally new world for me, and I'm excited to learn it.

I will connect the ground up correctly tonight and tinker with it some more.

Thanks for your help!

 

[aikx]

Some other details: the Teensy works fine otherwise in the current setup. I have separated the VIN and VUSB pads and power it only from a 5v/2A wall wart. I can write programs to make standard LEDs light, blink, etc. I know the LED strip is getting power because some of the LEDs flash when I plug in the barrel connector.

You need about 60 x 3 x 20mA. May be the power supply isn´t strong enough.
Its a good idea to test the logic with a single WS2812B or a NeoPixel Stick.

 

[dotbat]

Would it still not work even when trying to light a single pixel?

 

[dotbat]

Well, I figured out the the pre-soldered wires on the LED strip are on the wrong side (by design, but I didn't know that). So, that helps, but nothing will light up.

Question. If I measure voltage across the logic cable I can read voltage, but if I loop it through the 74AHCT125, I can't measure any voltage. What am I doing wrong with this?

I have changed around the setup a little. Here are pictures:
https://www.dropbox.com/s/dlrm41srxpbb6zw/2014-05-23 21.35.22.jpg
https://www.dropbox.com/s/3eif32by6mbbvs4/2014-05-23 21.36.17.jpg

 

[dotbat]

And now I figured out that if I have the logic running through the 74AHCT125 and ground it (the logic input to the LEDs) to one of the pins on the Teensy or even myself, some of the LEDs will light up. If I plug it into pin 3 while running OctoWS2811, then some random colors light up. The first few light up red if grounded to myself.

If it isn't running though the 74AHCT125, then nothing.

 

[dotbat]

Got it working! For anyone else having problems, here's what fixed it:

• I was sending logic into the wrong end of the strip. Check the arrows. Pre-soldered cables mean nothing
• The capacitor on the power of the strip was reducing the voltage. Removed.
• Make sure and use this adafruit library: https://github.com/PaulStoffregen/Adafruit_NeoPixel

The 74AHCT125 will work! So, yay!

Here are some pictures for anyone trying a similar setup: