Application experiment of analog-to-digital conversion DAC0832

[ Experimental task ]
Use two buttons to control the output of DAC0832 through the microcontroller, so that the OUT terminal can output two waveforms, sawtooth wave and triangle wave, with an amplitude of 0-5V and a frequency of 1KHZ. After the power is turned on; press INT1 to output a triangle wave, and press INT0 to output a sawtooth wave.

[ Experimental principle ]
ADC0804 is an 8-bit full MOS medium-speed D/A converter, using R-2RT resistor decoding network, the conversion result is a pair of differential current output, the conversion time is about 1us. Use a single power supply +5V-+15V. The reference voltage is -10V-+10V. Here we directly choose +5V as the reference voltage. DAC0832 has three working modes: direct mode, single buffer mode, double buffer mode; here we choose the direct mode, connect all XFER WR 1WR2 CS pins to digital ground. Pin 8 is connected to the reference voltage, and the reference voltage we connect here is +5V. Then after the first stage op amp, the output voltage will be -5V-0V, and after the second stage op amp inverts and amplifies 1 times, it can output 0V-5V. When we control the regular changes of the output data of P1 port, we can generate waveforms such as triangle wave, sawtooth wave, ladder wave, etc.

[ C language source program ]
#include
unsigned char keycnt=0;
unsigned char tcnt=0; //Key value judgment
bit sjz=0; //Flag used when generating triangle wave
void delayl() //Delay subroutine
{ unsigned char i,j;
for(i=20;i>0;i--)
for(j=248;j>0;j--); }
void KEY() //Key scanning program
{
if(P3_2==0)
{
delayl(); //Delay skips the jitter when pressing
if(P3_2==0)
{
keycnt=0; //Timer generates sawtooth wave flag
TR0=0; //Temporarily stop waveform output
TH0=0x256-40; //Assign TH0 TL0 to
TL0 TL0=0x256-40;
TR0=1; //Start timing and generate sawtooth wave
while(P3_2==0); //If the key is pressed all the time, wait for the key to be released to open
delayl(); //Delay to skip the jitter after releasing
} }
if(P3_3==0)
{
delayl(); //Delay to skip the jitter when pressing
if(P3_3==0)
{
keycnt=1; //Timer generates triangle wave flag
TR0=0; //Temporarily stop waveform output
TH0=0x256-40; //Assign TH0 TL0 value
TL0=0x256-40;
TR0=1; //Start timing to generate triangle wave
}
while(P3_2==0); //If the key is pressed all the time, wait for the key to be released to open
delayl(); //Delay to skip the jitter after releasing
}
} //Please pay attention to the format specification when writing the program, this is to save paper
void t0(void) interrupt 1 using 0 //Timer interrupt service function
{
if(keycnt==0) //Generate sawtooth wave
{
P0=tcnt;
tcnt=+0x0a; //Step 0.2V/one interruptif
(tcnt==0xfb)
{tcnt=0;}
}
if(keycnt==1) //Generate triangle wave
{ if(sjz==0)
{P0=tcnt;
tcnt=+0x0a;//Step 0.2V/one interruptif
(tcnt==0xfa)
{sjz=1;}
}
if(sjz==1)
{
P0=tcnt;
tcnt=-0x0a;
if(tcnt==0)
{sjz=0;}
}
}
}
void main(void)
{
TMOD=0x02; //Timer works in mode 2
ET0=1;
EA=1;
while(1)
{ KEY(); }
}

[Hardware Circuit Diagram]