- Tue Aug 18, 2015 4:45 am
#184127
Hi,
I am building a PCB with an 11 x 10 matrix of neopixel LEDs, WS2812B.
- I have a 1000uF cap on the VCC line coming in from a 9V adapter. It is then regulated to 4.95 volts.
- Using ATMEGA 328_TQFP to run the LEDs. 5V data signal.
- Data line has a 431 ohm resistor before the first LED
- 5 V powering the LEDs
- 0.1uF Capacitors at each LED
The first 10 LEDs light and respond fine. From there on, the string does not work. I replaced the 11th LED thinking it was damaged, but did not help.
I replaced LED 10. Did not help.
I then monitored the data signal with an oscilloscope and see that the Data Out signal from LED 10 does not have a nice flat top at 5 volts. (how can I attach an image without a URL?)
So it looks like LED 11 is not working due to a bad data signal from LED 10. Installed a new LED at LED 10 and it still had the same bad shape for Data Out.
LEDs 1 - 9 have signals that all look the same, clean flat top.
I compared my PCB data signal to the 8x8 Neopixel Matrix Adafruit sells. LEDs 1 - 9 have data out signals that looks like Adafruit's.
Any ideas on why my data out signal from LED number 10 suddenly looks different from other 9 LEDs?
Some sort of PCB design issue?? Have images of oscilloscope to attach, but do not know how.
Thanks for any advice.
Rich
I am building a PCB with an 11 x 10 matrix of neopixel LEDs, WS2812B.
- I have a 1000uF cap on the VCC line coming in from a 9V adapter. It is then regulated to 4.95 volts.
- Using ATMEGA 328_TQFP to run the LEDs. 5V data signal.
- Data line has a 431 ohm resistor before the first LED
- 5 V powering the LEDs
- 0.1uF Capacitors at each LED
The first 10 LEDs light and respond fine. From there on, the string does not work. I replaced the 11th LED thinking it was damaged, but did not help.
I replaced LED 10. Did not help.
I then monitored the data signal with an oscilloscope and see that the Data Out signal from LED 10 does not have a nice flat top at 5 volts. (how can I attach an image without a URL?)
So it looks like LED 11 is not working due to a bad data signal from LED 10. Installed a new LED at LED 10 and it still had the same bad shape for Data Out.
LEDs 1 - 9 have signals that all look the same, clean flat top.
I compared my PCB data signal to the 8x8 Neopixel Matrix Adafruit sells. LEDs 1 - 9 have data out signals that looks like Adafruit's.
Any ideas on why my data out signal from LED number 10 suddenly looks different from other 9 LEDs?
Some sort of PCB design issue?? Have images of oscilloscope to attach, but do not know how.
Thanks for any advice.
Rich
You do not have the required permissions to view the files attached to this post.
Last edited by RichKC on Tue Aug 18, 2015 6:26 pm, edited 2 times in total.