基于ATmega16单片机输出SPWM程序，PWM频率为25KHZ，输出正弦波为50HZ，输出电压波形光滑，失真度小，只需要硬件和软件相结合。电路简单，只修改程序就可以调整功能，成本低，可靠性主高。
#include <avr/io.h>
#include<avr/interrupt.h>
#define BIT(x) (1<<x)
//周期为20ms,产生50HZ的交流电，spwm频率为20k
const unsigned char list[]={1,4,7,10,13,16,19,22,25,28,31,34,37,39,42,45,48,51,54,57,60,62,
65,68,71,74,76,79,82,84,87,90,92,95,97,100,103,105,108,110,112,115,117,119,
122,124,126,128,131,133,135,137,139,141,143,145,147,149,151,152,154,156,157,
159,161,162,164,165,167,168,169,171,172,173,174,176,177,178,179,180,181,182,
182,183,184,185,185,186,186,187,187,188,188,189,189,189,189,189,189,189,189,
189,189,189,189,189,189,188,188,187,187,186,186,185,185,184,183,182,182,181,
180,179,178,177,176,174,173,172,171,169,168,167,165,164,162,161,159,157,156,
154,152,151,149,147,145,143,141,139,137,135,133,131,128,126,124,122,119,117,
115,112,110,108,105,103,100,97,95,92,90,87,84,82,79,76,74,71,68,65,62,60,57,
54,51,48,45,42,39,37,34,31,28,25,22,19,16,13,10,7,4,1};
//周期为20ms，产生50HZ的交流电，spwm频率为20k
int count,zf=0;
void port_init(void)
{
PORTB = 0x00;
DDRB = 0xFF;//b口输出
PORTC = 0x00;
DDRC = 0xFF;//c口输出
PORTD = 0x00;
DDRD = 0xFF;//d口输出
}
//TIMER1 initialize - prescale:1
// WGM13:0＝10) PWM phz correct, TOP= ICR1
// desired value: 10KHz
// actual value: 10.000KHz (0.0%)
void timer1_init(void)
{
TCCR1B = 0x00; //stop
TCNT1H = 0xFF; /
tup
TCNT1L = 0x38;
OCR1AH = 0x00;
OCR1AL = 0xC8;
OCR1BH = 0x00;
OCR1BL = 0xC8;
ICR1H = 0x00;
ICR1L = 200;// 载波周期为50us
TCCR1A = 0xA2; //10100010 top时更新OCR1A OCR1B，向上计数比较匹配清零，反之置位
TCCR1B = 0x11; //start Timer 00010001 clk无分频，相位修正PWM
TIMSK |= 0x20; //timer interrupt sources使能捕捉中断
}
//#pragma interrupt_handler timer1_capt_isr:7
ISR(TIMER1_CAPT_vect)
{ OCR1A=500; OCR1B=500;
if(zf)
{
if(count<200)
{
if(count==1) //此时2#管子才关断
{
//PORTB &= ~BIT(3); //3#管子已经关断
PORTB |= BIT(4); //开通4#管子
}
OCR1A=list[count++]; //开通1#管子
}
else if((count>=200)&&(count<400))
{
if(count==200)
{
PORTB &= ~BIT(4); //关断4#管子
}
if(count==201) //此时1#管子才关断
{
PORTB |= BIT(3); //开通3#管子
}
OCR1B=list[count++-200]; //开通2#管子
} else {
count=0; //2#管子已经关断
PORTB &= ~BIT(3); //关断3#管子
//PORTB |= BIT(4); //开通4#管子
OCR1A=list[count++]; //开通1#管子
} } else; }
//call this routine to initialize all peripherals
void init_devices(void)
{
//stop errant interrupts until set up
cli(); //disable all interrupts
port_init();
timer1_init();
sei(); //re-enable interrupts
//all peripherals are now initialized
}
// 主函数
int main(void)
{
init_devices();
//insert your functional code here...
zf = 1; OCR1A=500; OCR1B=500; PORTB = 0; while(1);
}