TLC5940, problems with leds staying on after they are faded

edocod · December 11, 2013, 2:06pm

Hi everyone!
I'm experimenting with some tlc5940 ICs and some leds for a project i'm making.
After some trying, i found the perfect setup for me but also some problems.

This is my current configuration:

A - 1500µF 10V ELNA capacitor to minimize ripple
B1 and B2 - Resistors to limit current, two in series for each chip since i don't have exact values
C - Arduino NANO connected to USB @ Ubuntu Studio
D1 and D2 - TLC5940 daisy chained
E - 5v From arduino, this is not used right now, the power for leds and chips is from a separate 10A @ 5V power supply.
F - 5v From 10A @ 5V power supply, used to power leds and chips
Green Line - Ground, common for arduino and chips/leds

These are the voltages i get from each supply (E is Arduino, F is power supply)

This is the code i have on the Arduino (C):

#include "Tlc5940.h" // Include TLC5940 library
#include "tlc_fades.h" // Include animation library
int incomingByte; // Var for serial data
int led = 0; // Var for led
 
void setup() {
	Tlc.init(); // Init TLC library
	Serial.begin(9600); // Open serial port, 9600bps
}
 
void loop() {
	incomingByte = Serial.read(); // Read the serial port and give its value to incomingByte
	if(incomingByte > 0) { // If i receive something from serial
		led = random(0,32); // Get a random led
		tlc_addFade(led, 0, 4096, millis(), millis()+80); // Add to the queue a fade from 0 to 4095 brightness from now to now+80ms
		tlc_addFade(led, 4096, 0, millis()+81, millis()+600); // Add to the queue a fade from now+81ms to now+600ms from 4095 to 0 brightness
	}
	tlc_updateFades(); // Update and display the fades.
}

Basically when i input something i get a fading led.

Now here's the problem. After a fade the led gets barely lit, as if i set the pwm to "1", you can't really see it, but some times it is very lit and you can notice it.
How can i resolve?

If i do a Tlc.Set(led, 0) after the fade the led stays off and the problem disappears, so i guess the problem is software, or maybe not working TLCs/Arduino?
Another thing i was thinking about, the data to the TLCs is sent via the pin 13. Could it be the led connected to that pin that messes up things?

Thank you and sorry for the poor English, i'm Italian

arduinodlb · December 11, 2013, 6:15pm

Hi,

I don't know the answer, but I congratulate you on a well detailed first post, including code with comments, inside code tags. This level of detail is rare for a first post.

fungus · December 11, 2013, 7:01pm

edocod:
If i do a Tlc.Set(led, 0) after the fade the led stays off and the problem disappears, so i guess the problem is software, or maybe not working TLCs/Arduino?

Sounds to me like a bug in the 'fade' functions.

But you already have a workaround for it...

edocod · December 11, 2013, 7:07pm

arduinodlb:
Hi,

I don't know the answer, but I congratulate you on a well detailed first post, including code with comments, inside code tags. This level of detail is rare for a first post.

Thank you. Since i'm not English i try to make my posts detailed as i can, hoping that it will compensate my language mistakes.
See you on the forum

fungus:

edocod:
If i do a Tlc.Set(led, 0) after the fade the led stays off and the problem disappears, so i guess the problem is software, or maybe not working TLCs/Arduino?

Sounds to me like a bug in the 'fade' functions.
But you already have a workaround for it...

Hi,
The problem is that it works only if you give the command seconds after the fade. If you try it immediately after it will not work.
I think the library is still managing the led some milliseconds after the fade, blocking every external command.

arduinodlb · December 11, 2013, 7:48pm

I just had a look at the tlc_fades.h file of the library here:
http://code.google.com/p/tlc5940arduino/source/browse/trunk/Tlc5940/tlc_fades.h

It looks to me like tlc_updateFades() should be working correctly, and result in a Tlc.set(led,0); at the end of the fade.

Is this the library you are using? Are you sure you have the latest version of the libraries? In your library tlc_fades.h file, just check if the uint8_t tlc_updateFades(uint32_t currentMillis) is identical to the one here.

edocod · December 11, 2013, 8:00pm

Hmm, let me check the library. It seems very old to me. I think it needs a rewrite.
I updated the library with the one you linked me but i have the same problems.
I found something new, though: the led that stays lit is not the one that fades, but the one adiacent to the fade.

00--03--05--07--09--11--13
--02--04--06--08--10--12--14

For example, if i fade the led 07, the leds 09 and 05 will stay lit.

arduinodlb · December 11, 2013, 8:04pm

The code you supplied only fades one led.

Can you post the complete code you are using?

edocod · December 12, 2013, 1:35pm

arduinodlb:
The code you supplied only fades one led.

Can you post the complete code you are using?

Hi,
the code i'm using is the one in the main post, if i enter three chars, i will get three leds fading. If i enter one, i will get only one led.

EDIT: I think i found a fix

[missing code...]
void setup() {
        Tlc.init(); // Init TLC library
        Tlc.setAll(0);
        Tlc.set(0,0);Tlc.set(1,0);Tlc.set(2,0);Tlc.set(3,0);
        Tlc.set(4,0);Tlc.set(5,0);Tlc.set(6,0);Tlc.set(7,0);
        Tlc.set(8,0);Tlc.set(9,0);Tlc.set(10,0);Tlc.set(11,0);
        Tlc.set(12,0);Tlc.set(13,0);Tlc.set(14,0);Tlc.set(15,0);
        Tlc.set(16,0);Tlc.set(17,0);Tlc.set(18,0);Tlc.set(19,0);
        Tlc.set(20,0);Tlc.set(21,0);Tlc.set(22,0);Tlc.set(23,0);
        Tlc.set(24,0);Tlc.set(25,0);Tlc.set(26,0);Tlc.set(27,0);
        Tlc.set(28,0);Tlc.set(29,0);Tlc.set(30,0);Tlc.set(31,0);
[missing code...]
}
 
void loop() {
       [missing code...]
        tlc_updateFades();
        Tlc.update();
        
        if(millis() % 20 == 0) {
          Tlc.setAll(0);
        }
}

This will reset all leds every 20ms. You can still see the leds staying on, but after 20ms they go off.
The problem was the library sending wrong data to the tlc and forgetting about it.

I'm not very happy with the solution, though, the leds flick every 20ms, but that's better than the leds staying on.

fungus · December 12, 2013, 3:00pm

edocod:
EDIT: I think i found a fix
        Tlc.setAll(0);

Tlc.set(0,0);Tlc.set(1,0);Tlc.set(2,0);Tlc.set(3,0);
Tlc.set(4,0);Tlc.set(5,0);Tlc.set(6,0);Tlc.set(7,0);
Tlc.set(8,0);Tlc.set(9,0);Tlc.set(10,0);Tlc.set(11,0);
Tlc.set(12,0);Tlc.set(13,0);Tlc.set(14,0);Tlc.set(15,0);
Tlc.set(16,0);Tlc.set(17,0);Tlc.set(18,0);Tlc.set(19,0);
Tlc.set(20,0);Tlc.set(21,0);Tlc.set(22,0);Tlc.set(23,0);
Tlc.set(24,0);Tlc.set(25,0);Tlc.set(26,0);Tlc.set(27,0);
Tlc.set(28,0);Tlc.set(29,0);Tlc.set(30,0);Tlc.set(31,0);

a) Didn't Tlc.setAll(0); already set them to 0
b) Ever hear of a thing called a loop?

edocod:
This will reset all leds every 20ms. You can still see the leds staying on, but after 20ms they go off.
The problem was the library sending wrong data to the tlc and forgetting about it.

I'm not very happy with the solution, though, the leds flick every 20ms, but that's better than the leds staying on.

Why don't you use the "tlc_isFading()" function to find out when a fade has finished and then set it to zero?

edocod · December 12, 2013, 4:34pm

fungus:
edocod:
EDIT: I think i found a fix
        Tlc.setAll(0);

Tlc.set(0,0);Tlc.set(1,0);Tlc.set(2,0);Tlc.set(3,0);
Tlc.set(4,0);Tlc.set(5,0);Tlc.set(6,0);Tlc.set(7,0);
Tlc.set(8,0);Tlc.set(9,0);Tlc.set(10,0);Tlc.set(11,0);
Tlc.set(12,0);Tlc.set(13,0);Tlc.set(14,0);Tlc.set(15,0);
Tlc.set(16,0);Tlc.set(17,0);Tlc.set(18,0);Tlc.set(19,0);
Tlc.set(20,0);Tlc.set(21,0);Tlc.set(22,0);Tlc.set(23,0);
Tlc.set(24,0);Tlc.set(25,0);Tlc.set(26,0);Tlc.set(27,0);
Tlc.set(28,0);Tlc.set(29,0);Tlc.set(30,0);Tlc.set(31,0);

a) Didn't Tlc.setAll(0); already set them to 0

Yeah, but better be sure

b) Ever hear of a thing called a loop?

Yes, but it was faster for me writing every line. My editor does it automatically

edocod:
This will reset all leds every 20ms. You can still see the leds staying on, but after 20ms they go off.
The problem was the library sending wrong data to the tlc and forgetting about it.

I'm not very happy with the solution, though, the leds flick every 20ms, but that's better than the leds staying on.

Why don't you use the "tlc_isFading()" function to find out when a fade has finished and then set it to zero?

Because the adiacent leds are the ones that are lit, not the fading one.

arduinodlb · December 12, 2013, 6:40pm

I don't believe this should be necessary.

I checked the tlc_updateFades() function in the library that I linked to, and at the end of the fade, it should automatically be calling setLed(Led,0).

So, something else is going on here. But, in order to fix it properly, we need you to post your entire code, not just parts of it.

If you want us to have a look at the problem, take out your hacks, and post the full code. And ideally, a link to the library you are using.

If you're happy with your solution and you don't want us to look, that's OK too.

edocod · December 12, 2013, 6:49pm

arduinodlb:
I don't believe this should be necessary.

I checked the tlc_updateFades() function in the library that I linked to, and at the end of the fade, it should automatically be calling setLed(Led,0).
[...]
If you're happy with your solution and you don't want us to look, that's OK too.

#include "Tlc5940.h" // Include TLC5940 library
#include "tlc_fades.h" // Include animation library
int incomingByte; // Var for serial data
int led = 0; // Var for led

void setup() {
Tlc.init(); // Init TLC library
Serial.begin(9600); // Open serial port, 9600bps
}

void loop() {
incomingByte = Serial.read(); // Get the serial
if(incomingByte > 0) { // Has the user inputted a byte?
led = random(0,32); // Choose a random led
tlc_addFade(led, 0, 4096, millis(), millis()+80); // Light it up
tlc_addFade(led, 4096, 0, millis()+81, millis()+600); //Shut it down
}

tlc_updateFades(); // Update everything
Tlc.update();

if(millis() % 20 == 0) { // Is the time a multiple of 20?
Tlc.setAll(0); //Then shut down all the leds so we start with a clean memory
}
}

And this is the library: Google Code Archive - Long-term storage for Google Code Project Hosting.
I just edited the config of the library to make it work with two tlc (there is a var for that)

fungus · December 12, 2013, 6:51pm

Something is very wrong.

Are you sure you've told the TLC library you have two chips connected?

edocod · December 12, 2013, 7:00pm

fungus:
Something is very wrong.

Are you sure you've told the TLC library you have two chips connected?

http://pastebin.com/hPHAffLU

This is my tlc_config.h, the only file i edited.

arduinodlb · December 12, 2013, 7:22pm

Ahhh. I understand now. Sorry, I didn't fully understand that was your entire code.

The problem seems to be in the Tlc.update(); function. The tlc_updateFades() looks like it should do the right thing, and it also calls Tlc.update(); at the end of the fade.

Unfortunately, I haven't worked with the TLC5940 and the Tlc.update() method is low-level chip stuff, so I can't really help you I'm afraid. I hope someone else here can help you though.

system · December 14, 2013, 1:34pm

edocod:

[missing code...]

void setup() {
Tlc.init(); // Init TLC library
Tlc.setAll(0);
Tlc.set(0,0);Tlc.set(1,0);Tlc.set(2,0);Tlc.set(3,0);
Tlc.set(4,0);Tlc.set(5,0);Tlc.set(6,0);Tlc.set(7,0);
Tlc.set(8,0);Tlc.set(9,0);Tlc.set(10,0);Tlc.set(11,0);
Tlc.set(12,0);Tlc.set(13,0);Tlc.set(14,0);Tlc.set(15,0);
Tlc.set(16,0);Tlc.set(17,0);Tlc.set(18,0);Tlc.set(19,0);
Tlc.set(20,0);Tlc.set(21,0);Tlc.set(22,0);Tlc.set(23,0);
Tlc.set(24,0);Tlc.set(25,0);Tlc.set(26,0);Tlc.set(27,0);
Tlc.set(28,0);Tlc.set(29,0);Tlc.set(30,0);Tlc.set(31,0);
[missing code...]
}

Or

[missing code...]
void setup() {
        Tlc.init(); // Init TLC library
        Tlc.setAll(0);
        For(int led = 0; led < 32; led++)
        {
          Tlc.set(led, 0);
        }
[missing code...]
}

edocod · December 14, 2013, 4:18pm

tack:
edocod:
[missing code...]

void setup() {
Tlc.init(); // Init TLC library
Tlc.setAll(0);
Tlc.set(0,0);Tlc.set(1,0);Tlc.set(2,0);Tlc.set(3,0);
Tlc.set(4,0);Tlc.set(5,0);Tlc.set(6,0);Tlc.set(7,0);
Tlc.set(8,0);Tlc.set(9,0);Tlc.set(10,0);Tlc.set(11,0);
Tlc.set(12,0);Tlc.set(13,0);Tlc.set(14,0);Tlc.set(15,0);
Tlc.set(16,0);Tlc.set(17,0);Tlc.set(18,0);Tlc.set(19,0);
Tlc.set(20,0);Tlc.set(21,0);Tlc.set(22,0);Tlc.set(23,0);
Tlc.set(24,0);Tlc.set(25,0);Tlc.set(26,0);Tlc.set(27,0);
Tlc.set(28,0);Tlc.set(29,0);Tlc.set(30,0);Tlc.set(31,0);
[missing code...]
}

Or

[missing code...]

void setup() {
Tlc.init(); // Init TLC library
Tlc.setAll(0);
For(int led = 0; led < 32; led++)
{
Tlc.set(led, 0);
}
[missing code...]
}

Thank you for the help, but that ended up in not being the problem.
I'll have to rewrite the entire library, since the one there is right now isn't working well.

Thank you for everyone that contributed on this thread.

AJB2K3 · December 14, 2013, 8:22pm

Not necessaries connected to your problem but your missing the bypass capacitors across the TLS's + and - line. (VSS & VDD)

edocod · December 14, 2013, 9:01pm

AJB2K3:
Not necessaries connected to your problem but your missing the bypass capacitors across the TLS's + and - line. (VSS & VDD)

The capacitor that is connected is also connected to the power supply of the TLCs.

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TLC5940, problems with leds staying on after they are faded

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