ISR for SGEN library

Hi Gautam,

So I tried using cpu timer 0 ISR which is called TINT0_ISR in the DefaultIsr.c file, while cpu timer 1 and 2 are said to be reserved for ti use. I initialized the cpu timer 0 first and map my own ISR to the TINT0 in the pievect table, then the sgen module was initialized. The code built fine but when I debugged it, the two variables x1 and x2 which were supposed to change continuously remained 26816 and 0, and I did refresh the watch window. The code below is the main.c I used. Do you have some suggestions on it? There was no compiling bug, so I couldn't figure out what was wrong. Thanks again for your time and patience with a beginner.

Best regards,
Haoyi

#include "DSP28x_Project.h" // Device Headerfile and Examples Include File
#include <sgen.h>
#include "IQmathLib.h"
interrupt void signal_isr(void);
SGENTI_2 sgen = SGENTI_2_DEFAULTS;
int x1,x2;
//20kHz
float freq = 0.02;
float period = 50;
void main()
{
InitSysCtrl();
InitCpuTimers();
ConfigCpuTimer(&CpuTimer0,freq,period);
DINT;
InitPieCtrl();
IER = 0x0000;
IFR = 0x0000;
InitPieVectTable();
EALLOW;
PieVectTable.TINT0 = &signal_isr;
EDIS;
// Enable CPU INT1
IER |= M_INT1;
// Enable TINT0 in the PIE: Group 1 interrupt 7
PieCtrlRegs.PIEIER1.bit.INTx7 = 1;
// Enable Global interrupt INTM
EINT;
// Enable Global realtime interrupt DBGM
ERTM;
sgen.offset=1024;
sgen.gain=_IQ15(0.03125);
sgen.freq=6443;
sgen.step_max=1000;
sgen.phase=_IQ15(1);
sgen.alpha=0;//8192;
for(;;);

}
interrupt void signal_isr(void)
{
sgen.calc(&sgen);
x1=sgen.out1;
x2=sgen.out2;
PieCtrlRegs.PIEIER1.bit.INTx7 = 1;
PieCtrlRegs.PIEIFR1.bit.INTx7 = 1;
PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}

Haoyi, try toggling GPIO in the ISR and check whether timer ISR is working as per expected.

Hi Gautam, I tried toggling gpio in both timer 0 and 1 interrupt which are TINT0_ISR and INT13_ISR at separate trials, but not one pin toggled when I scope them.

I don't know if it is my problem of initializing or using the gpio.

I initialized gpio 12 in my main function after the system control initialization.

void Init12Gpio(void)
{
EALLOW;
GpioCtrlRegs.GPAMUX1.bit.GPIO12 = 0x00;
GpioCtrlRegs.GPADIR.bit.GPIO12 = 1;
EDIS;
}

Then I modified the timer isr using code below.
EALLOW;
GpioDataRegs.GPATOGGLE.bit.GPIO12 = 1;
EDIS;

I didn't get error or warning, do you have any suggestion? Thanks.

Hi Gautam,

So the problem is solved, the pin toggled. I think it's probably because I initialized the timer wrong. And back to the original question, I also

succeed in storing sine values in variables using timer ISR. But I still have this question, how do I determine the actual frequency of the sine

signal? I'm not sure if it is the same frequency when I initialized sgen module. If yes, does that mean I need to increase the cpu interrupt

frequency to get better sine signal resemblance? Thanks a lot for your guidance.

Best regards,
Haoyi

Your cpu_timer will have to be very small as when you're in a for loop there's a continuous execution and no delay. You'll have to observe the signal on DSO and tune accordingly.