TLC59711 Light On But No One Home
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Re: TLC59711 Light On But No One Home

by adafruit_support_bill on Mon Sep 16, 2013 1:31 pm

What is RGBI? Those pins should be connected to the ground of your 12v supply. This should also be connected to the ground of your Pi.

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Re: TLC59711 Light On But No One Home

by jnovack on Mon Sep 16, 2013 1:53 pm

Referencing this diagram:

Image

The PWM cable is V+ (P1) through LAT (P6).
The RGBI cable is 0, 1, and 2.
The RGB+ cable is V+ row directly under 0, 1, and 2.

When I plug in the RGBI to be entirely GND, they are bright, however, are uncontrollable. The strip goes bright white and the PWM seems to be bypassed.
Last edited by jnovack on Mon Sep 16, 2013 1:59 pm, edited 2 times in total.
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Re: TLC59711 Light On But No One Home

by adafruit_support_bill on Mon Sep 16, 2013 1:57 pm

You want to connect RGBI to the gate of the MOSFET (where you have RGB+ connected now). This is your control signal.
You do not need to connect RGB+ - your strips are already getting power.
You need to connect the rightmost pin of the MOSFETs to ground.
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Re: TLC59711 Light On But No One Home

by jnovack on Mon Sep 16, 2013 2:03 pm

I think that was one of the one of the iterations I tried, but who knows now.

The Gate of the MOSFET is the 0,1,2.
The Drain of the MOSFET is the R, G, B out.
The Source of the MOSFET is the GND. Coming off the 12v?

So the only thing the PWM is doing is sending a data like signal to the MOSFET over the 0/1/2 line to the gate?

Do I still need the 1k Ohm resistors in place?
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Re: TLC59711 Light On But No One Home

by adafruit_support_bill on Mon Sep 16, 2013 2:07 pm

The Source of the MOSFET is the GND. Coming off the 12v?

All your grounds should be connected together (12v supply, Pi & TLC59711).

You should not need the resistor.

When the PWM signal line goes high on the Gate, the MOSFET will conduct current between the Source and the Drain. This will connect your LEDs to ground, completing the circuit from the positive side of the 12v supply.
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Re: TLC59711 Light On But No One Home

by jnovack on Mon Sep 16, 2013 2:13 pm

That makes a huge amount of sense. Thank you everyone. I'll try this out and post the finished diagram tonight when I get home.

This is so exciting and I appreciate the patience and knowledge of everyone here.
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Re: TLC59711 Light On But No One Home

by adafruit_support_rick on Mon Sep 16, 2013 3:01 pm

Sorry - you still need the resistor between V+ and the output signal. The output signal won't go high without it.

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Re: TLC59711 Light On But No One Home

by adafruit_support_bill on Mon Sep 16, 2013 3:09 pm

you still need the resistor between V+ and the output signal. The output signal won't go high without it.


I see. I looked like it was intended to limit the gate current..

You still want to connect RGBI to the Gate. Then connect the resistors between the gate and RGB+.
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Re: TLC59711 Light On But No One Home

by jnovack on Mon Sep 16, 2013 7:04 pm

Heh, it is MUCH brighter now, with one issue.

1 is 0 and 0 is 1.

When I set R to 0, G to 1, and B to 0, I would expect to see Green. However, I see Purple. It's lighting up Red and Blue, and Green is dark.

I can fix that programmatically, but is that right?
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Re: TLC59711 Light On But No One Home

by adafruit_support_bill on Mon Sep 16, 2013 7:11 pm

Yes. The logic is inverted. The TLC59711 turns on LEDs by pulling the output low. But the MOSFET turns them on when the gate is driven high. Since you are using the TLC59711 signal to drive the MOSFET, everything is inverted.
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Re: TLC59711 Light On But No One Home

by jnovack on Mon Sep 16, 2013 8:36 pm

Thank you, this solves the issue for the 24-channel PWM. I'll have to figure out how to wire the 12-channel PWM with my software before I repost back here.

You can add this to your file. :)
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Re: TLC59711 Light On But No One Home

by adafruit_support_rick on Mon Sep 16, 2013 10:17 pm

Yessir, that does look right!

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Re: TLC59711 Light On But No One Home

by jnovack on Fri Sep 20, 2013 5:38 pm

This went unnoticed when transitioning between colors, however, when attempting to send lots of commands quickly, the LED strip flashes white between transitions.

Even when I quickly send a single color very quickly repeatedly, the strip flashes white before being set. Is this a function of the PWM or the MOSFETs that is causing this?
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Re: TLC59711 Light On But No One Home

by adafruit_support_rick on Fri Sep 20, 2013 6:24 pm

Unfortunately, the flashing is a side effect of the way the PWM loads new data you send it. Essentially, it turns the PWM output off while loading the new PWM value. Since your logic is inverted, it shows up as a while flash.

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Re: TLC59711 Light On But No One Home

by jnovack on Sat Sep 21, 2013 7:02 am

Yuck. Is there a PWM that does not do this? I would be looking at the Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface - PCA9685 instead.
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