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下面代碼，我有一個(gè)問(wèn)題一直困擾我沒(méi)有解決，所以來(lái)51hei論壇跟大家請(qǐng)教。
定時(shí)器中斷1，用一個(gè)數(shù)組調(diào)整占空比。那么這個(gè)值，是怎么傳遞并替換掉ConfigPWM(100, 90)中的90的呀？
我理解是定時(shí)器1每50ms進(jìn)入一次，調(diào)整一次占空比。可定時(shí)器0，進(jìn)入后，也會(huì)把占空比調(diào)整成90呀？
我問(wèn)的問(wèn)題不知道大家能否明白，希望高手解答，謝謝！
這個(gè)程序在開(kāi)發(fā)板上跑過(guò)，能夠?qū)崿F(xiàn)呼吸燈效果，所以程序邏輯和語(yǔ)法都是正確的。
單片機(jī)源程序如下:
#include <reg52.h>
sbit PWMOUT = P0^0;
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
unsigned long PeriodCnt = 0; //PWM周期計(jì)數(shù)值
unsigned char HighRH = 0; //高電平重載值的高字節(jié)
unsigned char HighRL = 0; //高電平重載值的低字節(jié)
unsigned char LowRH = 0; //低電平重載值的高字節(jié)
unsigned char LowRL = 0; //低電平重載值的低字節(jié)
unsigned char T1RH = 0; //T1重載值的高字節(jié)
unsigned char T1RL = 0; //T1重載值的低字節(jié)
void ConfigTimer1(unsigned int ms);
void ConfigPWM(unsigned int fr, unsigned char dc);
void main()
{
EA = 1; //開(kāi)總中斷
ENLED = 0; //使能獨(dú)立LED
ADDR3 = 1;
ADDR2 = 1;
ADDR1 = 1;
ADDR0 = 0;
ConfigPWM(100, 90); //配置并啟動(dòng)PWM
ConfigTimer1(50); //用T1定時(shí)調(diào)整占空比
while (1);
}
/* 配置并啟動(dòng)T1，ms-定時(shí)時(shí)間 */
void ConfigTimer1(unsigned int ms)
{
unsigned long tmp; //臨時(shí)變量
tmp = 11059200 / 12; //定時(shí)器計(jì)數(shù)頻率
tmp = (tmp * ms) / 1000; //計(jì)算所需的計(jì)數(shù)值
tmp = 65536 - tmp; //計(jì)算定時(shí)器重載值
tmp = tmp + 12; //補(bǔ)償中斷響應(yīng)延時(shí)造成的誤差
T1RH = (unsigned char)(tmp>>8); //定時(shí)器重載值拆分為高低字節(jié)
T1RL = (unsigned char)tmp;
TMOD &= 0x0F; //清零T1的控制位
TMOD |= 0x10; //配置T1為模式1
TH1 = T1RH; //加載T1重載值
TL1 = T1RL;
ET1 = 1; //使能T1中斷
TR1 = 1; //啟動(dòng)T1
}
/* 配置并啟動(dòng)PWM，fr-頻率，dc-占空比 */
void ConfigPWM(unsigned int fr, unsigned char dc)
{
unsigned int high, low;
PeriodCnt = (11059200/12) / fr; //計(jì)算一個(gè)周期所需的計(jì)數(shù)值
high = (PeriodCnt*dc) / 100; //計(jì)算高電平所需的計(jì)數(shù)值
low = PeriodCnt - high; //計(jì)算低電平所需的計(jì)數(shù)值
high = 65536 - high + 12; //計(jì)算高電平的定時(shí)器重載值并補(bǔ)償中斷延時(shí)
low = 65536 - low + 12; //計(jì)算低電平的定時(shí)器重載值并補(bǔ)償中斷延時(shí)
HighRH = (unsigned char)(high>>8); //高電平重載值拆分為高低字節(jié)
HighRL = (unsigned char)high;
LowRH = (unsigned char)(low>>8); //低電平重載值拆分為高低字節(jié)
LowRL = (unsigned char)low;
TMOD &= 0xF0; //清零T0的控制位
TMOD |= 0x01; //配置T0為模式1
TH0 = HighRH; //加載T0重載值
TL0 = HighRL;
ET0 = 1; //使能T0中斷
TR0 = 1; //啟動(dòng)T0
PWMOUT = 1; //輸出高電平
}
/* 占空比調(diào)整函數(shù)，頻率不變只調(diào)整占空比 */
void AdjustDutyCycle(unsigned char dc)
{
unsigned int high, low;
high = (PeriodCnt*dc) / 100; //計(jì)算高電平所需的計(jì)數(shù)值
low = PeriodCnt - high; //計(jì)算低電平所需的計(jì)數(shù)值
high = 65536 - high + 12; //計(jì)算高電平的定時(shí)器重載值并補(bǔ)償中斷延時(shí)
low = 65536 - low + 12; //計(jì)算低電平的定時(shí)器重載值并補(bǔ)償中斷延時(shí)
HighRH = (unsigned char)(high>>8); //高電平重載值拆分為高低字節(jié)
HighRL = (unsigned char)high;
LowRH = (unsigned char)(low>>8); //低電平重載值拆分為高低字節(jié)
LowRL = (unsigned char)low;
}
/* T0中斷服務(wù)函數(shù)，產(chǎn)生PWM輸出 */
void InterruptTimer0() interrupt 1
{
if (PWMOUT == 1) //當(dāng)前輸出為高電平時(shí)，裝載低電平值并輸出低電平
{
TH0 = LowRH;
TL0 = LowRL;
PWMOUT = 0;
}
else //當(dāng)前輸出為低電平時(shí)，裝載高電平值并輸出高電平
{
TH0 = HighRH;
TL0 = HighRL;
PWMOUT = 1;
}
}
/* T1中斷服務(wù)函數(shù)，定時(shí)動(dòng)態(tài)調(diào)整占空比 */
void InterruptTimer1() interrupt 3
{
static bit dir = 0;
static unsigned char index = 0;
unsigned char code table[13] = { //占空比調(diào)整表
5, 18, 30, 41, 51, 60, 68, 75, 81, 86, 90, 93, 95
};
TH1 = T1RH; //重新加載T1重載值
TL1 = T1RL;
AdjustDutyCycle(table[index]); //調(diào)整PWM的占空比
if (dir == 0) //逐步增大占空比
{
index++;
if (index >= 12)
{
dir = 1;
}
}
else //逐步減小占空比
{
index--;
if (index == 0)
{
dir = 0;
}
}
}
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