AVR Freaks

hi all,

   good day.  I am struggling to figure out how to and where to  set the bit values for led brightness. In my application i want to setting bits for LED brightness control through hyper-terminal. I don't want to do LED ON in OVF. I read the data sheet in that after low the BLANK GS counter will increment and it reaches 4096 then BLANK is high. And the Brightness control is through 12 bits. How to set these bits and where to set it. Can you please help me where i am getting struck. It is something different and i like to learn.  My piece of code i have tried and circuit is,

/*
 * PWM_TLC5940NT.c
 *
 * Created: 12/12/2014 4:53:16 PM
 *  Author: Dev5
 */ 

#define F_CPU 8000000UL

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include <stdio.h>


void uart0_init(void)
{
	UCSRA=0x00;
	UCSRB=0x18;
	UCSRC=0x06;
	UBRRH=0x00;
	UBRRL=0x33;
}

unsigned char receiveByte( void )
{
	while(!(UCSRA & (1<<RXC))); 	// Wait for incoming data

	return UDR;
}

void transmitByte( unsigned char data )
{
	while ( !(UCSRA & (1<<UDRE)) )
	; 			                /* Wait for empty transmit buffer */
	UDR = data; 			        /* Start transmition */
}

void transmitString(char* string)
{
	while (*string)
	transmitByte(*string++);
}


int main(void)
{
	unsigned int GS_counter = 0, Data_counter = 0;
	
	DDRB = (1<<PB5)|(1<<PB7)|(1<<PB4);
	PORTB |= (1<<PB4);             // CS pin is not active
	
	SPCR = (1<<SPE)|(1<<MSTR);    // Enable SPI, Master, set clock rate fck/2
	SPSR |= (1<<SPI2X);
	_delay_ms(100);
	
	
	DDRD |= (1<<PD4)|(1<<PD5);                    //OC1A, OC1B outputs
	
	//Timer 1
	TCCR1A = (2<<COM1A0)|(2<<COM1B0)|(2<<WGM10);  //PWM#14, active-high LEDs
	TCCR1B = (3<<WGM12)|(3<<CS10);                //PWM#14, div64
	ICR1 = F_CPU/64/100 - 1;                      //OVF @ 100Hz
	TIMSK |= (1<<TOV1);
	
	
	uart0_init();
	_delay_ms(500);
	
	transmitString("\n\n\nin main");
	
	
	
	while(1)
    {
        //TODO:: Please write your application code 
		
		transmitString("\nin loop");
		
		PORTB &= ~(1<<PB4);    //BLANK low for GS counter increment
		
		GS_counter++;
		
		PORTD = 0x30;
		//OUTn switch ON  AND SET BIT VALUE FOR led BRIGHTNESS
		if(GSCLK_counter>4095)
		{
			PORTB |= (1<<PB4);     //BLANK high for OUTn switch OFF
			GS_counter = 0;	
			PORTD = 0x00;
		}
		
    }
	return 0;            // Standard Return Code
}

   Good day.  

I would just connect an LED (with resistor) to OC1A and OC1B pins.    Then experiment with different PWM  modes and different duty-cycles.

 

Then connect the TLC5940 to the SPI pins.    And send commands to the TLC5940 that control the light form LEDs connected to OUT0 .. OUT15.

I connected LED(with resistor) to OC1A and OC1B pins and also i connected LED's to OUT pins also. In this case the  LED(with resistor) connected in OC1A and OC1B pins are less brightness and LED's connected in OUT  pins are very good brightness and it is not getting dim and off. always on.