Posted on April 03, 2013 at 13:09
ok, thanks for the tip.
i cross checked asm code and loop cycle speed, and now i know real problem.
in main loop i was doing floating point MAC, 256 times with adc data.
when i write anything what will going to use data from MAC compiler will include my floating point operations to assembler code.
so in short, when i try to print calculated phase from main loop to DAC, it start to include all floating point operations from main loop, so in general f32 to in32 is fast only problem i have more floating point operations elsewhere.
so that was wrong interpretation what compiler is doing, and it's doing quite a good job.
original loop to see what i did...
while(k<
128
)
{
cosinusas[k]=cosf((6.28318531*k*POINT)/N);
sinusas[k] =sinf((6.28318531*k*POINT)/N);
k++;
}
while(1)
{
while(GPIOA->IDR <
32766
);
GPIOD->BSRRL= GPIO_Pin_13;
while(GPIOA->IDR > 32766);
while(GPIOA->IDR <
32766
);
GPIOD->BSRRH= GPIO_Pin_13;
imag=0;
real=0;
i=0;
a=0;
while(i<
128
)
{
while(GPIOC->IDR <
32766
);
CLK_LOW;
CLK_HIGH;
k
=
GPIOB
->IDR;
real+=k*cosinusas[i]; // FMAC
imag-=k*sinusas[i]; // FMAC
i++;
}
faze=faze-(0.2*Angle(imag,real));
if(fabsf(faze)>0f)
faze=0;
DAC_DATA=(int)(faze*375+32767);
}
while(GPIOC->IDR <
32766
)
is for FIFO buffer to get data from adc , so i read only when fifo buffer is not empty, so in this loop lost 700ns of time,
(clock is 8MHz so all data is loaded in in 16us, and unloaded in 7us, so it is acceptable)
Two FMAC operations i
n
while(i<
128
)
loop cost me 4us of time, and angle calculation,
If(...) condition checking and printing float to DAC cost me additional 2us.
I don't know, can i do better than this ?
or does any one know fast and cheap processor for this kind of work ?
