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A couple of initial questions
MUFF WIGGLER Forum Index -> nw2s  
Author A couple of initial questions
After playing with this unit for a week, I am really enjoying it but I came across one observation and two problems during my setup (I built this from the kit).

First, anyone who is building this from a kit and has sensitive eyes should really consider replacing the blue LEDs with something other. I find the unit useless with these LEDs on. Anything over 20% sent to the Adafruit board is too bright for me. On full - pilots flying overhead are blinded. I have disabled all of these until I replace them this weekend. Truth be told, I typically will not buy anything with blue LEDs if at all possible - I should have known, but I wanted to build the kit as sent before modifying it. cry evil MINI-RANT OFF.

1) I can not get the noise random pot to get the percentage to anything lower than around 82% using bTestRNGTuning - the pot does adjust it from 82% to 100%. I have the noise at 18V P-P. Any ideas? Also, the noise source has a high ~120Hz/240Hz component - definitely audible - are all like this?

2) I have paired the unit with bluetooth, have used the serial monitor to monitor the print, have used the DTR to reset the unit, and have used ERASEANDRESET to erase and reset when appropriate programs are loaded BUT I have yet been able to upload a sketch via BT. I get a "no device found on cu.AdafruitEZ... after the ERASEANDRESET when attempting an upload. I am using an old iMAC if that matters - absolutely no problems with the USB except for port accessibility.

Regarding the LED brightness... Good news is that you can set it to be as bright as you want.

The decision to use a high-efficiency LED was a conscious one.

Using standard LEDs, with 32 potentially being on at 20mA each, you're talking about 640mA just powering LEDs.

The greens have 1k resistors which puts them at about 3mA each.

The blues run at 20mA, but pulse width modified at about 1/5 that (with the stock 'b code base) so that's effectively 4mA.

Grand total of 112mA. Still not a tiny amount compared to most modules, but a significant savings over 640.

If they are too bright, simply open up PCA9685.cpp, line 52, and change the 50 to something like 100 or even more if you like. Adjust to taste! Looking at the code, it looks like I was doing some work fine tuning it and never really cleaned it up.


writeLED(ledNumber, 0, 0 + ((amount * 10) / 50)); cpp

Of course you are right - for some reason I was thinking I am loosing resolution - now I realize 12 bit resolution for an LED is a huge-bit nutty. Not only did I limit the On time for the PWM where you said, but I also limited the input to the LED call to 0 - 100. Still overkill. hmmm.....
Well, you can get the LED down to just a faint glow, but I suspect that you may just not like blue. That's fair.

As to the noise, that does sound odd. The first things I would look for are making sure all of the filter caps are in the right direction, the transistors are in the right direction, all the solder joints are solid, and that none of the op-amp pins are bent.

Have you tested the two DAC outputs? If they don't have the same hum and gain problems, then it's likely in the noise circuit rather than the op-amp.

I'll think about some other tests that could help...

Is it possible to have all LEDs default to off when the unit is powered on, so that there isn't this huge flash in the beginning until your code runs? This will help with the initial in-rush current requirements too.
Hm. Good question. I'll have to take a look at that one.
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