TLC59711: RGB LED flickering issue

Ismail Mohammed

Part Number: TLC59711
Other Parts Discussed in Thread: TIDA-00979, TLC5971

Hi,

I am using RGB LED drivers (2 No's) in daisy chain to drive 8 RGB LEDS. When I try to drive single RGB LED with yellow color, other RGB LEDS are flickering with same yellow color with less intensity.

Observation:
With single write operation to the LED drivers (224 bit for each driver), LED flickering is seen. LEDs which should remain OFF was turning ON for a moment and then goes OFF.(Like Flickering).

Thanks and Regards,

Mohammed Ismail

over 6 years ago

0 Kenneth Du over 6 years ago

TI__Genius 14295 points

Hi, Mohammed,

Can you please try just send one TLC59711 data to test whether it is OK for one device?

Please send me your schematic so I can check the hardware.

Thanks.

Regards,

Kenneth

0 Ismail Mohammed over 6 years ago in reply to Kenneth Du

Prodigy 30 points

Hi Kenneth,

Thanks for your reply.

I tried by removing one LED driver IC. It worked fine with one LED driver.

Below are the schematics.

Thanks and Regards,

Mohammed Ismail

0 Kenneth Du over 6 years ago in reply to Ismail Mohammed

TI__Genius 14295 points

Hi, Mohammed,

The schematic is OK.

Since one device works well, I think it's probably the code is not correct.

Here are the TLC5971 code for TIDA-00979:

4135.3113.TLC5971.c

#include "TLC5971.h"

// Initialisation of array with 5 lamps
char lamps[5][4][3] = { { { 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 } },
						{ { 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 } },
						{ { 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 } },
						{ { 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 } },
						{ { 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 },{ 0x00, 0x00, 0x00 } } };


//command setup
char cd[5][4] = {{ WRITECMD, DSPRPT + 0x1F, 0xFF, 0xFF },
				 { WRITECMD, DSPRPT + 0x1F, 0xFF, 0xFF },
				 { WRITECMD, DSPRPT + 0x1F, 0xFF, 0xFF },
				 { WRITECMD, DSPRPT + 0x1F, 0xFF, 0xFF },
				 { WRITECMD, DSPRPT + 0x1F, 0xFF, 0xFF }};

//data set to be written
void sendData()
{
	char l = 5;

	do
	{
		l--;

		char b = 0;

		while (b < 4)
		{
			write(cd[l][b]);
			b++;
		}
		write(lamps[l][3][BLUE_OR_GREEN]);
		write(lamps[l][3][BLUE_OR_GREEN]);
		write(lamps[l][3][GREEN_OR_BLUE]);
		write(lamps[l][3][GREEN_OR_BLUE]);
		write(lamps[l][3][RED]);
		write(lamps[l][3][RED]);

		write(lamps[l][2][BLUE_OR_GREEN]);
		write(lamps[l][2][BLUE_OR_GREEN]);
		write(lamps[l][2][GREEN_OR_BLUE]);
		write(lamps[l][2][GREEN_OR_BLUE]);
		write(lamps[l][2][RED]);
		write(lamps[l][2][RED]);

		write(lamps[l][1][BLUE_OR_GREEN]);
		write(lamps[l][1][BLUE_OR_GREEN]);
		write(lamps[l][1][GREEN_OR_BLUE]);
		write(lamps[l][1][GREEN_OR_BLUE]);
		write(lamps[l][1][RED]);
		write(lamps[l][1][RED]);

		write(lamps[l][0][BLUE_OR_GREEN]);
		write(lamps[l][0][BLUE_OR_GREEN]);
		write(lamps[l][0][GREEN_OR_BLUE]);
		write(lamps[l][0][GREEN_OR_BLUE]);
		write(lamps[l][0][RED]);
		write(lamps[l][0][RED]);
	}
	while (l > 0);
	_delay_cycles(0x1FF);
}

//Funtion to blanking or turning on LEDs
void blank(char lamp, char status)
{
	if (status)
	{
		cd[lamp][1] |= BLANK;
	}
	else
	{
		cd[lamp][1] &= ~BLANK;
	}
}

//set global brightness function
void setGlobalBrightness(char lamp, char color, char value)
{
	if (color == RED)
	{
		cd[lamp][3] &= 0x80;
		cd[lamp][3] |= (0x7F & value);
	}
	else if (color == GREEN_OR_BLUE)
	{
		(value & BIT0) ? (cd[lamp][3] |= BIT7) : (cd[lamp][3] &= ~BIT7);
		cd[lamp][2] &= 0xC0;
		cd[lamp][2] |= (0x3F & (value >> 1));
	}
	else
	{
		(value & BIT0) ? (cd[lamp][2] |= BIT6) : (cd[lamp][2] &= ~BIT6);
		(value & BIT1) ? (cd[lamp][2] |= BIT7) : (cd[lamp][2] &= ~BIT7);
		cd[lamp][1] &= 0xE0;
		cd[lamp][1] |= (0x1F & (value >> 2));
	}
}

//set brightness function
void setBrightness(char lamp, char row, char color, char value)
{
	lamps[lamp][row][color] = value;
}

//Get brightness function
char getBrightness(char lamp, char row, char color)
{
	char roworder [4] = {1,0,3,2};
	return lamps[lamp][roworder[row]][color];
}

//Set color function
void setColor(char lamp, char row, char red, char green, char blue)
{

	char roworder [4] = {1,0,3,2};
	lamps[lamp][roworder[row]][RED] = red;
	lamps[lamp][roworder[row]][GREEN] = green;
	lamps[lamp][roworder[row]][BLUE] = blue;

}

//data write
void write(char data)
{
	while (!(UCB1IFG & UCTXIFG));
	UCB1TXBUF = data;
}

//TODO: eliminate this function completely
// delay func in milliseconds (with 100ms resolution)
volatile int delay_timer;
void delay(int i)
{
	/*for(; i>0; i--)
		__delay_cycles(1000);*/
	if(i/100 == 0)i = 100; //to fix delays below 100ms
	delay_timer = 0;
	while(delay_timer < i/100);
}

2043.TLC5971.h

Please take for reference and check your code.

Thanks.

Regards,

Kenneth

0 Ismail Mohammed over 6 years ago in reply to Kenneth Du

Prodigy 30 points

Hi Kenneth,

I see that the issue is with internal latch timing requirement. During heavy loading of the system, we are not able to meet this requirement.

Thanks and Regards,
Mohammed Ismail

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TLC59711: RGB LED flickering issue