Notes

Experiment 4

part 1:Generate 4 different
Frequencies using the 4 Timers

*T1:50HZ:RB5
*T0:200HZ:RB3
*T2:400HZ:RB4
*T3:100HZ:RB6
------
ISIS:
pin 25:with virtual terminal
oscilloscope pins :
pin A:with pin 38
pin B:with pin 39
pin C:with pin 36
pin D:with pin 37
-----
code:
#include "ee470.h"
unsigned char T0L, T0H, T1L, T1H, T2, T3L, T3H;
void main(void)
{
unsigned int X, N, pre;
unsigned char n;
float Tcyc=0.5e-6, Ttick, T, Ttoggle;
OSCCON=0x70;
ADCON1=0xF;
serial_init(51,1);
TRISB3=0;
TRISB4=0;
TRISB5=0;
TRISB6=0;
T0CON=0b00000010;
T1CON=0x30;
T2CON=0b00000011;
T3CON=0b00110100;
// T0: 200Hz calculations
pre=8; Ttick=pre*Tcyc; T=1.0/200.0; Ttoggle=T/2.0;
N=(unsigned int) (Ttoggle/Ttick); X=0xFFFF+1-N;
T0H=(X>>8); T0L=((X<<8) >> 8);
7 printf("T0: N=%u, Ttoggle=%g, X=%urn", N,Ttoggle,X);
// T1: 50Hz calculations
pre=8; Ttick=pre*Tcyc; T=1.0/50.0; Ttoggle=T/2.0;
N=(unsigned int) (Ttoggle/Ttick); X=0xFFFF+1-N;
T1H=(X>>8); T1L=((X<<8) >> 8);
printf("T1: N=%u, Ttoggle=%g, X=%urn", N,Ttoggle,X);
// T2: 400Hz calculations
pre=16; Ttick=pre*Tcyc; T=1.0/400.0; Ttoggle=T/2.0;
n=(unsigned char) (Ttoggle/Ttick);
PR2=n-1; // Timer2 is an 8-bit timer
printf("T2: n=%u, Ttoggle=%g rn", n,Ttoggle);
// T3: 100Hz calculations
pre=8; Ttick=pre*Tcyc; T=1.0/100.0; Ttoggle=T/2.0;
N=(unsigned int) (Ttoggle/Ttick); X=0xFFFF+1-N;
T3H=(X>>8); T3L=((X<<8) >> 8);
printf("T3: N=%u, Ttoggle=%g, X=%urn", N,Ttoggle,X);
TMR0IF=0;
TMR1IF=0;
TMR2IF=0;
TMR3IF=0;
TMR0ON=1;
TMR1ON=1;
TMR2ON=1;
TMR3ON=1;
while(1)
{
if(TMR0IF==1)
{
TMR0H=T0H;
TMR0L=T0L;
TMR0IF=0;
RB3=RB3^1;
}
if(TMR1IF==1)
{
TMR1H=T1H;
TMR1L=T1L;
TMR1IF=0;
RB5=RB5^1;
}
if(TMR2IF==1)
{
// TMR2=0;
TMR2IF=0;
RB4=RB4^1;
}
if(TMR3IF==1)
{
TMR3H=T3H;
TMR3L=T3L;
TMR3IF=0;
RB6=RB6^1;
}
}
}
###############
part 2:Frequency Measurement
of a Square Wave via counting
Pulses in One second

-----
ISIS:

pin 25 : to virtual terminal

RC0:connected with signal generator (sin)
then connected to osclliscope (pin A)

the other pin in signal generator (squ)
connected to gnd.
--------
code :
#include "ee470.h"
unsigned long NTicksT1;
unsigned char T1prescaler;
float freq;
void main(void) {
unsigned char pres;
OSCCON=0x70; // 8MHz, T machine cycle=4*1/8=0.5us
ADCON1=0xF;
serial_init(51,1);
TRISC0 = 1; // input to get incoming pulses
T1CON=0b00000010; // ext. clk T13CKI=RC0, T1 prescaler=1
T1prescaler=1;
TMR1H=TMR1L=0;
TMR1ON=1;
Delay10KTCYx(200);
TMR1ON=0; // stop Timer1
NTicksT1=T1prescaler*(TMR1L+(TMR1H<<8));// similat to T0 read L then H (Little E)
printf("NTicksT1=%urn",NTicksT1);
}