DAC-08 as Digital potentiometer

Interfacing of Digital to analog converter for the development of Digital Volume control for Inverter motor control.

Many Inverter or 3-phase motor controller in industry have input 0-10V and an analog variable resistance is used to change the voltage which result in change in speed of the motor controlled by that Inverter. With the passage of time this potentiometer does not work fine. So, people try to find digital potentiometer which can give 0-10V digitally by the use of two push buttons.

This project is of digital volume control or digital potentiometer. Micro controller At89s52 0r any 8051 family microcontroller can be used with DAC08, or DAC-0800. The theme of project is very simple, two push button are used as input, one for increment and other for decrement of values between 0 to 255, this byte is then feed to digital to analog converter dac-08, the output current from DAC is converted to voltage between 0-10V accordingly. The circuit is simple and can be used any where.

Code or program for this circuit is written in Kiel c51 compiler, c source code is as follows,

sbit incr = P1^7; // PUSH button for increment in the speed

sbit decr = P1^6; // PUSH button for decrement in the speed

unsigned char vol = 0; // value of voltage which are then used by DAC-08

void main (void)

{

incr = 1;

decr = 1;

P2 = 0;

while(1)

{

incr = 1;
decr = 1;

if(incr==0) { vol ++; if(vol >= 254) vol = 254; }

if(decr ==0){ vol--; if(vol <= 1) vol = 1;}

delay(500); // delay of 500mSec

P2 = vol; // DAC is interface with P2 of microcontroller

}

}

Circuit diagram for the interfacing of DAC-08 with micro-controller

Source: http://microcontroller51.blogspot.com/2009/07/dac-08-as-digital-potentiometer.html