nitin.joshi52@gmail.com
Newbie level 5
hi.
i am using dspic33fj64mc802.
writing code in 16 bit C compiler.
sine wave frequency is 50 HZ and PWM frequency is 5000 hz.
initially i have written code for generating pwm only.
Later on i changed it as per sine wave PWM.
instead of giving pwm with varying frequency according to change in amplitude of sine wave it is giving peak at some points.
please help.
i am using dspic33fj64mc802.
writing code in 16 bit C compiler.
sine wave frequency is 50 HZ and PWM frequency is 5000 hz.
initially i have written code for generating pwm only.
Later on i changed it as per sine wave PWM.
instead of giving pwm with varying frequency according to change in amplitude of sine wave it is giving peak at some points.
please help.
Code:
//sine wave pwm with centre aligned up down count mode
//sine wave frequency =50 HZ
//triangular wave freq. = 5000 HZ.
#include<xc.h>
#include<p33FJ64MC802.h>
#include<pwm.h>
#define MOTOR_DUTY 60 //motor duty in %
void motor_init()
{
//setup PWM ports
PWM1CON1 = 0; //clear all bits (use defaults)
PWM1CON1bits.PMOD1 = 0; //PWM1L PWM1H are in complementry mode
PWM1CON1bits.PEN1L = 1; //PWM1L1 pin is enabled for PWM output
PWM1CON1bits.PEN1H = 1; //PWM1H1 pin is enabled for PWM output
P1TCON = 0; //clear all bits (use defaults)
P1TCONbits.PTMOD = 0b10; //up down count mode
P1TCONbits.PTCKPS = 0b01; // 1:4 prescaler
P1TPER = 0x5C; // some how managed by mathematical calculation for 1:4 prescalar (decimal value =92) to get 5K HZ PWM
P1TMR = 0; //ENABLE PWM1
IFS3bits.PWM1IF = 0; // disable flag
IEC3bits.PWM1IE = 1; // enable Flag
P1TCONbits.PTEN = 1; //PWM time base is on
}
/////////////// globally defined cnt and sine wave look up table values (20ms/0.2ms)=100 values
int cnt =0;
static int Sine[] = {32768,
34825,
36874,
38908,
40916,
42893,
44830,
46719,
48553,
50325,
52028,
53654,
55198,
56654,
58015,
59277,
60434,
61482,
62416,
63234,
63931,
64506,
64955,
65277,
65470,
65535,
65470,
65277,
64955,
64506,
63931,
63234,
62416,
61482,
60434,
59277,
58015,
56654,
55198,
53654,
52028,
50325,
48553,
46719,
44830,
42893,
40916,
38908,
36874,
34825,
32768,
30710,
28661,
26627,
24619,
22642,
20705,
18816,
16982,
15210,
13507,
11881,
10337,
8881,
7520,
6258,
5101,
4053,
3119,
2301,
1604,
1029,
580,
258,
65,
0,
65,
258,
580,
1029,
1604,
2301,
3119,
4053,
5101,
6258,
7520,
8881,
10337,
11881,
13507,
15210,
16982,
18816,
20705,
22642,
24619,
26627,
28661,
30710};
int main()
{
motor_init();
return 0;
}
//ISR == interrupt service routine
void __attribute__((interrupt, no_auto_psv))_MPWM1Interrupt()
{
IFS3bits.PWM1IF= 0;
IEC3bits.PWM1IE = 0;
for(cnt=0;cnt<100;cnt++)
{
P1DC1 = Sine[cnt];
}
IFS3bits.PWM1IF =0;
//RETFIE;
}