利用51单片机实现频率测量

利用51单片机定时器实现频率测量，不同单片机晶振不同，实际使用按实际单片机晶振频率求计数器初值。

#include "reg52.h"	

#define  _capacity 40 //计40次

typedef unsigned char u8;
typedef unsigned int u16;
typedef unsigned long int u32;

sbit LSA = P2 ^ 2;
sbit LSB = P2 ^ 3;
sbit LSC = P2 ^ 4;
sbit test = P1 ^ 0;

void Delay(u16 i) //i=1时，大约延时10us
{
	while (i--);
}

void PositionSele(u8 a, u8 b, u8 c)
{
	LSA = a; LSB = b; LSC = c;
	Delay(100);
}

u32 Sum(u16* first, u16* last)
{
	u32 _value = 0;
	for (; first != last; ++first)
		_value = _value + *first;
	return _value;
}

void TimerTnit()
{
	TMOD = 0x15; //定时器1定时,T0计数，模式1
	TH1 = 0x9E; //25ms
	TL1 = 0x58;
	EA = 1;
	ET1 = 1;
	TR1 = 1;
	TR0 = 1;
}

u8 count_times = 0;
u16 count[_capacity];
void Timer1() interrupt 3
{
	TR0 = TR1 = 0;
	count[count_times++] = (TH0 << 8) | TL0;
	TH0 = TL0 = 0;
	TH1 = 0x9E;
	TL1 = 0x58;
	TR0 = TR1 = 1;
	test = ~test;
}

u8 code segment_code[10] = { 0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
						0x7f,0x6f }; //显示0~9的值
void DigDisplay(u8 val)
{
	P0 = segment_code[val / 100000 % 10]; //发送段码
	PositionSele(1, 1, 1);

	P0 = segment_code[val / 10000 % 10];
	PositionSele(0, 1, 1);

	P0 = segment_code[val / 1000 % 10];
	PositionSele(1, 0, 1);

	P0 = segment_code[val / 100 % 10];
	PositionSele(0, 0, 1);

	P0 = segment_code[val / 10 % 10];
	PositionSele(1, 1, 0);

	P0 = segment_code[val % 10];
	PositionSele(0, 1, 0);
}

void main()
{
	u32 value = 0;
	TimerTnit();
	while (1)
	{
		if (count_times == _capacity)
		{
			TR0 = TR1 = 0;
			value = Sum(count, &count[_capacity]);
			count_times = 0;
			TR0 = TR1 = 1;
		}
		DigDisplay(value);
	}
}