本帖最后由 zhaosr19 于 2011-9-5 20:02 编辑
请教一下 16f723 timer2定时问题，内部时钟，16Mhz，按照下面计算是16Mhz/（4*16*16）= 15625，但我在程序中对Timer2定时3ms，PR2 = 0.003*15625=47
我在main函数中有如下操作，但通过管脚输出发现这个定时不对，至少差2倍，能帮忙看看是我算错了？
另外，Timer1，Timer0我都是用了，这个有影响？谢谢
TMR2 = 0;
PR2 = 47;
TMR2ON = 1;
#include <htc.h>
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 16000000/* 内部晶振16MHz */
#endif
#define _XTAL_FREQ_1_16 1000000/* 1/16 * _XTAL_FREQ */
#define _TIMER1_FREQ 500000 /* 1/4 Focs，8分频 */
#define _TIMER2_FREQ 15625 /* 1/4 Focs，16,16分频 */
//大4倍
#define NORMAL_OUT 3.0 /* ms */
#define NORMAL_OUT_NUM 47/* NORMAL_OUT * _TIMER2_FREQ */
#define HIGH_OUT 2.5 /* ms */
#define HIGH_OUT_NUM 39/* HIGH_OUT * _TIMER2_FREQ */
typedef union {
struct {
unsigned bFlag_RB5 : 1;
unsigned ucTimer1Flag : 1;
unsigned bFlag : 1;
unsigned ucTimer2Flag : 1;
unsigned ucFlagNorOrHigh : 2;/* 1 Normal,2 High */
unsigned uOutFlag : 1;
unsigned uClose : 1;
};
unsigned char ucFlag;
}FlagBit;
volatile FlagBit ubFlagBit;
volatile unsigned short g_uslT3=0;
unsigned char ucFlagTemp1 =0, ucFlagTemp2 =0, g_fFreq = 0;//,temp[10];
volatile unsigned char ucTimer1RollOver = 0;
volatile unsigned short usTimer2_NUM = 0,usTimer2_NUMPre = 0;
unsigned char ucAngle = 0;
union tag_TimerValue
{
struct
{
unsigned L:8;
unsigned H:8;
}Value;
unsigned short Timer;
};
volatile union tag_TimerValue g_uslT1,g_uslT2;
void Init(void)
{
INTCON = 0x00;
PIE1 = 0x00;
PIR1 = 0x00;
TRISA = 0b00000100; /* 0输出,1 input, AN2 */
ANSELA = 0b00000100; /* 1 Analog input */
TRISB = 0b00100001; /* RB5,RB0;RB3 ccp */
ANSELB = 0x00; /* 0 IO, 1 Analog input */
WPUB = 0x00100001; /* 1 pull-up enabled, RB5,RB0,与OPTION_REG有关 */
IOCB = 0b00100000; /* 1 Interrupt-on-change enabled, RB5 */
TRISC = 0x00;
#if 0
CCP2SEL = 1; /* CCP2 function is on RB3/CCP2 */
CCP2CON = 0x00; /* reset ccp */
CCP2CON = 0x00000100;/* Capture mode, every falling edge */
CCP2IE = 1;
CCP2IF = 0;
#endif
/* AD */
ADCON1 = 0b00000011;/* Fosc/2, Vref internal Fixed Voltage Reference */
ADCON0 = 0b00001001;
FVRCON = 0b11000011;/* 4.096 */
ADON = 1;
/* timer1 */
T1CON = 0b00110101;/* 1/4 *Fosc ，预分频8*/
//T1CON = 0x01;//ccp
T1GCON = 0x00;
TMR1IE = 1;
/* timer0 */
CPSCON0 = 0x00; /* Timer0 clock source is Fosc/4 */
OPTION_REG = 0b00000001;/* portb上拉,独立控制；INT脚下降沿中断，预分频 4，内部 Fosc/4 */
/* timer2 */
T2CON = 0b01111011;/* postscaler 16,prescaler 16, timer off 4MHz/16/16 = 15,625*/
TMR2IE = 1;
TMR2IF = 0;
/* interrupt */
INTE = 1;
INTF = 0;
T0IE = 0;
T0IF = 0;
TMR1IF = 0;
RBIE = 1;/* portb change interrupt enable */
RBIF = 0;
PEIE = 1;
GIE = 1;
__delay_us(1000);/*1000us*/
}
/* Ad采集 */
unsigned int ReadAD(int iNum)
{
unsigned int uiAdValue = 0;
unsigned char j = iNum;
unsigned char uiAdMax = 0,uiAdMin = 255;
unsigned char ucAdValue;
for (; j > 0; j--)
{
GO = 1;
while(GO)
{
continue;
}
ucAdValue = ADRES;
if (ucAdValue > uiAdMax)
{
uiAdMax = ucAdValue;
}
if (ucAdValue < uiAdMin)
{
uiAdMin = ucAdValue;
}
uiAdValue += ucAdValue;
/* 如果不准可以考虑加入nop(); */
}
uiAdValue = (uiAdValue - uiAdMax - uiAdMin)/(iNum -2);
return uiAdValue;
}
void interrupt my_isr(void)
{
unsigned char ucTemp = 0;
if (1 == TMR2IE && 1 == TMR2IF)
{
TMR2IF = 0;
if (1 == RA0)
{
RA0 = 0;
}
else
{
RA0 = 1;
}
return;
}
#if 0
if (1 == CCP2IF)
{
CCP2IF = 0;
ucFlagTemp1 =CCPR2H;
ucFlagTemp2 =CCPR2L;
}
#endif
}
void main(void)
{
unsigned char ucAdValInit = 0;
volatile unsigned char ucAdVal = 0,ucAdValCurrent = 0;
unsigned char ucTemp = 0;
unsigned char i = 0 ,j = 0,k=0;
Init();
ubFlagBit.ucFlag = 0;
g_uslT2.Timer = 0;
g_uslT1.Timer = 0;
PORTB = PORTB;
ucAdValInit = ReadAD(5);
//temp
TMR2ON = 1;
TMR2 = 0;
PR2 = 255;//NORMAL_OUT_NUM;// 255; 32.5ms
while(1)
{
;
}
return;
}
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