dac0800 not working properly

[samic45mit1]

HI,

I am working on dac 0800 interfaced with atmega32. But when I run a simple counter then dac 0800 not give expected output. connection between microcontroller and dac is correct and digital output of microcontroller is also correct. And I am getting all supply properly. Only at +Vref of dac I getting no voltage but before 4.7k resistance it is 5V. And I use 2k on i to v converter in place of 4.7k. My circuit and wave from is attached.So please guide me to solve this.

/**********************************************************************************************************************************************/
int main(void)
{
	unsigned char i=0;
	
	PORTD=0XFF;
	DDRD=0XFF;	
    /* Replace with your application code */
    while (1) 
    {
	 i=i+1;
	 
	 if (i>=250)
	 {
	  i=0;
	 }
		  _delay_ms(50);
	 	
      PORTD=i;
	}
}

 

[FvM]

You don't show the ATmega part of the circuit. I see that DAC800 LSB is unusually connected to A8, may be it's just misconnected data lines.

 

[samic45mit1]

I also give fix value by putting "PORTD=254" or "PORTD=128" but on 254 it give full output (this is correct) but on 128 it give 0.7V. So and DSO also show correct voltage level on microcontroller port pins and there is no voltage drop portd pin.Please see the reference voltage pin. As I told I getting 0V on +Vref pin of DAC but before 4.7K it is 5V. So this is correct??

 

[FvM]

Please see the reference voltage pin. As I told I getting 0V on +Vref pin of DAC but before 4.7K it is 5V. So this is correct??

Yes.

I noticed an error in your application schematic. Vlc must be connected to ground to achieve correct logic thresholds for µC control.

Floating Vlc pin can well explain the reported arbitrary output signal levels.

 

[samic45mit1]

I connect Vlc with ground and also give +12V on +v and also on pin 14 by 4.7k resistance. but still not working.

 

[samic45mit1]

Please any one provide me exect schematic how to interface dac0800 with avr

 

[KlausST]

Hi,

Please any one provide me exect schematic how to interface dac0800 with avr

May I ask why you don´t provide the complete schematic instead? Read post#2.

Klaus