📄 exp-iir-ad.c
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/********************************************************************************
The programme of the IIR filter (Butterworth type, 2 order).
Using INT2 to get the input signal.
Array x is the input signal from A/D, the length is 256, 32-bit floating point.
Array y the filter output signal, the length is 256, 32-bit floating point.
Array a and b are the coefficient of the IIR filter, the length is 3.
*********************************************************************************/
#pragma CODE_SECTION(vect,"vect")
#include "stdio.h"
#include "math.h"
#define pi 3.1415927
#define IMR *(pmem+0x0000)
#define IFR *(pmem+0x0001)
#define PMST *(pmem+0x001D)
#define SWCR *(pmem+0x002B)
#define SWWSR *(pmem+0x0028)
#define AL *(pmem+0x0008)
#define CLKMD 0x0058 /* clock mode reg*/
#define Len 256
double fs,pass,nlpass,nlstop,nhpass,nhstop,a[3],b[3],x[Len],y[Len];
void biir2lpdes(double fs, double nlpass, double nlstop, double a[], double b[]);
void biir2hpdes(double fs, double nhpass, double nhstop, double a[3], double b[3]);
unsigned int *pmem=0;
ioport unsigned char port8001;
int in_x[Len];
int *data=( int *)0x1000;
int m = 0;
int intnum = 0;
double xmean=0;
int n=0;
int flag = 0;
int i,j,p,k=0;
double w2,w1,w0;
int past_value,past_one,past_two,past_three;
void cpu_init()
{
*(unsigned int*)CLKMD=0x0; //switch to DIV mode clkout= 1/2 clkin
while(((*(unsigned int*)CLKMD)&01)!=0);
*(unsigned int*)CLKMD=0x17ff; //switch to PLL
PMST=0x3FA0;
SWWSR=0x7fff;
SWCR=0x0000;
IMR=0;
IFR=IFR;
}
interrupt void int1()
{
in_x[m] = port8001;
in_x[m] &= 0x00FF;
m++;
intnum = m;
if (intnum == Len)
{
intnum = 0;
xmean = 0.0;
for (i=0; i<Len; i++)
{
xmean = in_x[i] + xmean;
}
xmean = 1.0*xmean/Len;
for (i=0; i<Len; i++)
{
x[i] = 1.0*(in_x[i] - xmean);
}
for (i=0; i<Len; i++)
{
w2 = x[i]-a[1]*w1-a[2]*w0;
y[i] = b[0]*w2+b[1]*w1+b[2]*w0;
w0 = w1;
w1 = w2;
}
m=0;
flag = 1;
}
}
void biir2hpdes(double fs, double nhpass, double nhstop, double a[3], double b[3])
{
int n,i,u;
double wp,omp,gsa;
double pk,t;
wp=nhpass*2*pi;
omp=tan(wp/2.0);
n=2;
pk=-2.0*cos(((2.0*1+n-1.0)/(2.0*n))*pi);
gsa=omp*omp;
for (i=0; i<=2; i++)
{
u=i%2;
a[i]=gsa*pow(2,u)-pk*omp*(i-1)+pow(-2,u);
}
for (i=0; i<=2; i++)
{
u=i%2;
b[i]=pow(-2,u);
}
t=a[0];
for (i=0; i<=2; i++)
{
a[i]=a[i]/t;
b[i]=b[i]/t;
}
}
void biir2lpdes(double fs, double nlpass, double nlstop, double a[], double b[])
{
int i,u,v;
double wp,omp,gsa,t;
wp=nlpass*2*pi;
omp=tan(wp/2.0);
gsa=omp*omp;
for (i=0; i<=2; i++)
{
u=i%2;
v=i-1;
a[i]=gsa*pow(2,u)-sqrt(2)*omp*v+pow(-2,u);
}
for (i=0; i<=2; i++)
{ u=i%2;
b[i]=gsa*pow(2,u);
}
t=a[0];
for (i=0; i<=2; i++)
{ a[i]=a[i]/t;
b[i]=b[i]/t;
}
}
void set_int()
{
asm(" ssbx intm");
IMR=IMR|0x0004;
asm(" rsbx intm");
}
void main(void)
{
w2=w1=w0=0.0;
cpu_init();
fs = 250000;
set_int();
past_value=*data&0x01;
if(past_value==0x01)
{
nlpass = 0.01;
nlstop = 0.21;
biir2lpdes(fs,nlpass,nlstop,a,b);
}
else if(past_value==0x00)
{
nhpass=0.1;
nhstop=0.01;
biir2hpdes(fs,nhpass,nhstop,a,b);
}
past_one=past_value;
for(;;)
{
past_value=*data&0x01;
// past_two=(*data&0x0e)>>1;
/* switch(past_two)
{
case 0 :nlpass = 0.01;
nhpass = 0.05;
break;
case 1 :nlpass = 0.02;
nhpass = 0.06;
break;
case 2 :nlpass = 0.03;
nhpass = 0.07;
break;
case 3 :nlpass = 0.04;
nhpass = 0.08;
break;
case 4 :nlpass = 0.05;
nhpass = 0.09;
break;
case 5 :nlpass = 0.06;
nhpass = 0.10;
break;
case 6 :nlpass = 0.07;
nhpass = 0.11;
break;
case 7 :nlpass = 0.08;
nhpass = 0.2;
break;
}*/
if(past_one!=past_value)
{
if(past_value==0x01)
{
nlpass = 0.01;
nlstop = 0.21;
past_one=past_value;
past_three=past_two;
biir2lpdes(fs,nlpass,nlstop,a,b);
}
else if(past_value==0x00)
{
nhpass=0.1;
nhstop=0.001;
past_one=past_value;
past_three=past_two;
biir2hpdes(fs,nhpass,nhstop,a,b);
}
}
if (flag == 1)
{
flag = 0; /* set breakpoint here */
}
}
}
void vect()
{
asm(" .ref _c_int00");/*pseudoinstruction*/
asm(" .ref _int1");
asm(" b _c_int00");/* reset */
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* int0 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete");
asm(" nop"); /* int1 */
asm(" nop");
asm(" nop");
// asm(" rete"); /* int2 */
asm(" b _int1");
asm(" nop");
asm(" nop");
// asm(" nop");
asm(" rete"); /* tint0 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* brint0 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* bxint0 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* dmac0 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* tint1 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* int3 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* hpint */
asm(" nop");
asm(" nop");
asm(" rete"); /* brint1 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* bxint1 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* dmac4 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" rete"); /* dmac5 */
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
asm(" nop");
}
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