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DAC0832 simulating with Proteus and Arduino

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pabspagg

New Member
Hi,
I am doing a project for an electronic class I am taking.
What I have to do is : Using an arduino as a counter ( 8 bits Counter) connected to a DAC0832 and in the output generating a Sine wave ( I can't use arduino for generating the sine wave. I will use amp ops later ). The last part I haven't simulate yet.
Cicuito Proteus com simulação.PNG

The problem is the following: I want the wave output to be triangular at first, with steps ups and downs . But now I am only getting the steps going down ( I am using an AMP OP inverter) and it's not going up ( Why not? ) . As you can see in the image, the arduino code is working 100%. It's going from 0 to 255 then 255-0. ( I am only showing part of it).

ArduinoContagem.PNG

Thanks a lot!
Sorry for the bad english :)
 

ericgibbs

Well-Known Member
Most Helpful Member
hi p,
Look at this clip from the datasheet, the Vout polarity is negative.
E
A002.gif
 

ericgibbs

Well-Known Member
Most Helpful Member
hi p,
Try to simulate this version of the circuit taken from the datasheet.
E
A003.gif
 

ericgibbs

Well-Known Member
Most Helpful Member
hi p,
If you post your program listing I am sure one of us could help.
Looking at your print out, you seem to be incrementing the DAC input, in one bit steps, the input inc/dec should follow a Sine wave sequence.
E
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
Can you post the code.... The simulation shows a ramp output... Its the code you need to change.. you have decreasing amounts going to the DAC but then when it hits bottom you need to slowly increase not start all over!!
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
When portd-- != 0.... It'll mess up with this...

The easier way is an index

C:
int inc = 1;
void setup() {
   PORTD = 0;
   DDRD = 255;
}

void loop()
   {
    PORTD += inc;
    delay(100);
     if ( PORTD > 254 ) inc = -1;
     if ( PORTD < 1 ) inc = 1;
    }
 
Last edited:

pabspagg

New Member
After trying a lot to solve the problem. The issue was indeed the code. It turned out that it wasn't a viable option using PORT manipulation on arduino .
Here's the new one .
Code:
int led[8] = {0,1,2,3,4,5,6,7};
boolean A[8];
int inc=1;
int saida=0;

void setup() {  
  for(int i=0;i<8;i++)  {   
    pinMode(led[i], OUTPUT);  
  }  
}

void loop() {  
  saida += inc;  
  if( saida > 254 )  {   
      inc= -1;  
    }  
  if( saida < 1 )  {   
      inc= 1;  
    }  
  conversor();  
 
  for(int i=0;i<8;i++)  {   
    digitalWrite(led[i],A[i]);  
  }  
}
void conversor(){
  int valor=saida;
  for(int i=0;i<8;i++)  {
      if(valor%2>0)    {
          A[i]=1;
        }
        else    {
          A[i]=0;
        }
      valor=(valor/2);
    }
  }
The output I am getting now. There's some noise. I'm still trying to figure out how to remove this.

new.PNG
 
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