Frequency Meter
History
Here is my new Frequency meter who was done with a LCD's cellular phone!!! This is a simple project. The Frequency is passing through an op-amp to convert it in a square wave. The ouput of the op-amp is feeding the 3*8 bits counter (24 bits) who can accumulate at a maximum of 16777216 count. The maximum frequency you can measure without changing the time base of one second is 16.777216 Mhz. The ATMega8 have 3 functions: enable the counter gate at each second, read his value and display it on the LCD.
Features
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Small box |
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Frequency and period display |
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Auto Scale |
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LCD back light |
Pictures
Click to enlarge
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Outside |
Inside |
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Sources codes & Schematics
Use the Nokia LCD Library to make this code work
//**************************************************************************
// Frequancy Meter
// Version 1.0 Mars 2003
//
// 1.0 -> -First Release
//
//
// Sylvain Bissonnette
//**************************************************************************
/*********************************************************/
/* I N C L U D E */
/*********************************************************/
#include "macros.h"
#include "iom8v.h"
#include <stdio.h>
#include <stdlib.h>
#include <STRING.H>
#include "NokiaLCD.h"
/*********************************************************/
/* E X T E R N */
/*********************************************************/
extern char UpdateLcd;
/*********************************************************/
/* P R O T O T Y P E */
/*********************************************************/
void Delay(int del);
void timer1_compa_isr(void);
void timer0_ovf_isr(void);
void GetCount(void);
void PrintFreq(void);
void Presentation(void);
void main(void);
/*********************************************************/
/* D E F I N E */
/*********************************************************/
#define TRUE 1
#define FALSE 0
#define CLR 0x20
#define OEH 0x10
#define OEM 0x08
#define OEL 0x04
/*********************************************************/
/* G L O B A L V A R I A B L E S */
/*********************************************************/
unsigned long Count;
unsigned long Time;
/*********************************************************/
void Delay(int del)
{
int i,j;
for (j=0;j<del;j++)
{
for (i=0;i<320;i++);
}
}
/*********************************************************/
#pragma interrupt_handler timer1_compa_isr:7
void timer1_compa_isr(void)
{
if ((PINB & 0x02) == 0x02)
{
GetCount();
PrintFreq();
}
}
/*********************************************************/
#pragma interrupt_handler timer0_ovf_isr:10
void timer0_ovf_isr(void)
{
if (UpdateLcd == TRUE) LcdUpdate();
}
/*********************************************************/
void GetCount(void)
{
Count = 0;
PORTD &= ~OEH;
Delay(1);
Count = (unsigned long)((PINC & 0x3f) + (PIND & 0xc0));
PORTD |= OEH;
Count = Count << 8;
PORTD &= ~OEM;
Delay(1);
Count += (unsigned long)((PINC & 0x3f) + (PIND & 0xc0));
PORTD |= OEM;
Count = Count << 8;
PORTD &= ~OEL;
Delay(1);
Count += (unsigned long)((PINC & 0x3f) + (PIND & 0xc0));
PORTD |= OEL;
PORTD &= ~CLR;
Delay(1);
PORTD |= CLR;
}
/*********************************************************/
void PrintFreq(void)
{
char Str[7];
char Tmp[7];
unsigned char Len;
LcdGotoXY(1,4);
LcdStr(2," ");
LcdGotoXY(2,4);
LcdStr(2," ");
ltoa(&Str[0],Count,10);
Len = strlen(&Str[0]);
Str[Len] = 0x00;
if (Count < 1000)
{
LcdGotoXY(12-(2*Len),4);
LcdStr(2,&Str[0]);
LcdGotoXY(13,3);
LcdStr(1," " );
Time = 100000 / Count;
ltoa(&Str[0],Time,10);
if (Count <= 1000)
{
Tmp[0] = Str[0];
Tmp[1] = '.';
Tmp[2] = Str[1];
Tmp[3] = Str[2];
}
if (Count <= 100)
{
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = '.';
Tmp[3] = Str[2];
}
if (Count <= 10)
{
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = Str[2];
Tmp[3] = ' ';
}
if (Count == 0)
{
Tmp[0] = ' ';
Tmp[1] = ' ';
Tmp[2] = '0';
Tmp[3] = ' ';
}
Tmp[4] = 'm';
Tmp[5] = 's';
Tmp[6] = 0x00;
LcdGotoXY(9,6);
LcdStr(1,&Tmp[0]);
return;
}
if (Count < 10000)
{
Tmp[0] = Str[0];
Tmp[1] = '.';
Tmp[2] = Str[1];
Tmp[3] = Str[2];
Tmp[4] = Str[3];
Tmp[5] = 0x00;
LcdGotoXY(2,4);
LcdStr(2,&Tmp[0]);
LcdGotoXY(13,3);
LcdStr(1,"K" );
Time = 1000000 / Count;
ltoa(&Str[0],Time,10);
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = Str[2];
Tmp[3] = ' ';
Tmp[4] = 'u';
Tmp[5] = 's';
Tmp[6] = 0x00;
LcdGotoXY(9,6);
LcdStr(1,&Tmp[0]);
return;
}
if (Count < 100000)
{
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = '.';
Tmp[3] = Str[2];
Tmp[4] = Str[3];
Tmp[5] = Str[4];
Tmp[6] = 0x00;
LcdGotoXY(1,4);
LcdStr(2,&Tmp[0]);
LcdGotoXY(13,3);
LcdStr(1,"K" );
Time = 10000000 / Count;
ltoa(&Str[0],Time,10);
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = '.';
Tmp[3] = Str[2];
Tmp[4] = 'u';
Tmp[5] = 's';
Tmp[6] = 0x00;
LcdGotoXY(9,6);
LcdStr(1,&Tmp[0]);
return;
}
if (Count < 1000000)
{
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = Str[2];
Tmp[3] = '.';
Tmp[4] = Str[3];
Tmp[5] = Str[4];
Tmp[6] = 0x00;
LcdGotoXY(1,4);
LcdStr(2,&Tmp[0]);
LcdGotoXY(13,3);
LcdStr(1,"K" );
Time = 100000000 / Count;
ltoa(&Str[0],Time,10);
Tmp[0] = Str[0];
Tmp[1] = '.';
Tmp[2] = Str[1];
Tmp[3] = Str[2];
Tmp[4] = 'u';
Tmp[5] = 's';
Tmp[6] = 0x00;
LcdGotoXY(9,6);
LcdStr(1,&Tmp[0]);
return;
}
if (Count < 10000000)
{
Tmp[0] = Str[0];
Tmp[1] = '.';
Tmp[2] = Str[1];
Tmp[3] = Str[2];
Tmp[4] = Str[3];
Tmp[5] = Str[4];
Tmp[6] = 0x00;
LcdGotoXY(1,4);
LcdStr(2,&Tmp[0]);
LcdGotoXY(13,3);
LcdStr(1,"M" );
Time = 1000000000 / Count;
ltoa(&Str[0],Time,10);
Tmp[0] = Str[0];
Tmp[1] = Str[1];
Tmp[2] = Str[2];
Tmp[3] = ' ';
Tmp[4] = 'n';
Tmp[5] = 's';
Tmp[6] = 0x00;
LcdGotoXY(9,6);
LcdStr(1,&Tmp[0]);
return;
}
}
/*********************************************************/
void Presentation(void)
{
unsigned char i;
LcdClear();
LcdUpdate();
LcdGotoXY(3,1);
LcdStr(1,"Freq Meter" );
for (i=0;i<9;i++) LcdLine(0,i,83,i,PIXEL_XOR);
LcdGotoXY(5,3);
LcdStr(1,"Sylvain");
LcdGotoXY(3,4);
LcdStr(1,"Bissonnette");
LcdGotoXY(4,6);
LcdStr(1,"Ver : 1.0");
LcdUpdate();
Delay(10000);
LcdClear();
LcdUpdate();
}
/*********************************************************/
void main(void)
{
unsigned char i;
LcdInit();
LcdClear();
LcdUpdate();
Presentation();
LcdGotoXY(3,1);
LcdStr(1,"Freq Meter" );
for (i=0;i<9;i++) LcdLine(0,i,83,i,PIXEL_XOR);
LcdGotoXY(12,4);
LcdStr(1," hz" );
LcdGotoXY(2,4);
LcdStr(2," 0");
LcdGotoXY(1,6);
LcdStr(1,"Period: " );
TCCR0 = 0x05; //start timer0 / 1024
DDRB = 0x3f;
DDRC = 0x00;
DDRD = 0x3e;
PORTD |= OEH;
PORTD |= OEM;
PORTD |= OEL;
PORTD |= CLR;
//TIMER1 initialisation - prescale:256
// WGM: 4) CTC, TOP=OCRnA
// desired value: 2000mSec
// actual value: 2000.000mSec (0.0%)
TCCR1B = 0x00;
OCR1AH = 0x7A;
OCR1AL = 0x11;
TCCR1A = 0x40;
TCCR1B = 0x0C;
TIMSK = 0x11; //timer interrupt sources
SEI(); //re-enable interrupts
while(1)
{
Delay(10);
}
}