All leds are too bright
Closed this issue · 8 comments
Hello!
Thanks for a great library!
I`ve bought 2m LPD8806 strip and trying to use it with RPI. Powering it off ATX PSU via molex connector.
When starting example.py all leds light up on maximum brightness.
Colors are changing, but chaotically, not smooth like in your library.
Here is the video:
http://www.youtube.com/watch?v=vYSRQso3hak
Do you have any suggestions on this strange behaviour?
Thanks in advance!
Wow... those are crazy bright. Where did you get the lights from?
Are you using a signal level converter? The chaotic changing seems to be a
signal problem.
On Wed, Feb 12, 2014 at 4:44 PM, Ruslan Gainutdinov <
notifications@github.com> wrote:
Hello!
Thanks for a great library!I`ve bought 2m LPD8806 strip and trying to use it with RPI. Powering it
off ATX PSU via molex connector.When starting example.py all leds light up on maximum brightness.
Colors are changing, but chaotically, not smooth like in your library.
Here is the video:
http://www.youtube.com/watch?v=vYSRQso3hakDo you have any suggestions on this strange behaviour?
Thanks in advance!Reply to this email directly or view it on GitHubhttps://github.com//issues/12
.
I am not very proficient in electronics.
Got it from adafruit, www.adafruit.com/products/306
Ive just connected DI/CI to MOSI/SCLK directly, as recommended. The only issue I observe myself is ATX PSU giving out 5.3 on molex without load. Also Ive got Raspberry PI from production batch which is known to have bad soldering resulting in overheating under load, but after baking it in oven, it is working ok.
Where was it recommended to hook up the signal lines directly?
Yes, in theory it works, but 3.3V is technically below the logic level
threshold for the LPD8806 chips.
You can hook them up directly ONLY if using a 5V microcontroller, but the
Rasp Pi is 3.3V.
I use one of these: http://www.adafruit.com/products/757
Also, 5.3V is too high, and probably why they are so bright. You won't burn
them out at that voltage, but it's sill not good.
On Wed, Feb 12, 2014 at 11:07 PM, Ruslan Gainutdinov <
notifications@github.com> wrote:
I am not very proficient in electronics.
Got it from adafruit, www.adafruit.com/products/306Ive just connected DI/CI to MOSI/SCLK directly, as recommended.
The only issue I observe myself is ATX PSU giving out 5.3 on molex without
load.
Also Ive got Raspberry PI from production batch which is known to have
bad soldering resulting in overheating under load, but after baking it in
oven, it is working ok.Reply to this email directly or view it on GitHubhttps://github.com//issues/12#issuecomment-34946620
.
Thanks for the link and help.
I will try to connect to Arduino to see if led strip is ok.
Getting adafruit level converter is difficult, the shipping will take months.
Maybe I can assemble it myself.
For what its worth I have the exact same LEDs from adafruit running off an
RPi. I only have 1m connected, but it works perfectly at 5v for power and
3.3v logic from the RPi.
Have you tried lighting the LEDs up one at a time and seeing how it
reacts? It could be the strand is too long and not getting enough power at
the far end, or the power supply can't provide enough amps to turn all the
LEDs on at once.
I avoided using direct ATX PSU 5v line and used instead LM2596 based stabilizer to get 12v -> 5v to power ledstrip.
Using such power supply and connected to arduino everything works (every led is controllable and not so bright)
However, using it in RPI gives same random result.
I reinstalled Raspian from scratch,
and lowered hw spi frequency to 1Mhz, no difference.
Is there any way to debug SPI on RPI?
Thanks for help.
Sorry for the long hiatus... did you ever get this working?
Yes, everything is working proper once I added pullup resistors and connected all GND of all power sources together. Sorry for bothering you with this slightly offtopic teach-me-electronics non-issue.