#include
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 char HighRH = 0; //高电平重载值的高字节
unsigned char HighRL = 0; //高电平重载值的低字节
unsigned char LowRH = 0; //低电平重载值的高字节
unsigned char LowRL = 0; //低电平重载值的低字节
void ConfigPWM（unsigned int fr， unsigned char dc）;
void ClosePWM;
void main{
unsigned int i;
EA = 1; //开总中断
ENLED = 0; //使能独立 LED
ADDR3 = 1;
ADDR2 = 1;
ADDR1 = 1;
ADDR0 = 0;
while （1）{
ConfigPWM（100， 10）; //频率 100Hz，占空比 10%
for （i=0; i40000; i++）;
ClosePWM;
ConfigPWM（100， 40）; //频率 100Hz，占空比 40%
for （i=0; i40000; i++）;
ClosePWM;
ConfigPWM（100， 90）; //频率 100Hz，占空比 90%
for （i=0; i40000; i++）;
ClosePWM; //关闭 PWM，相当于占空比 100%
for （i=0; i40000; i++）;
}
}
/* 配置并启动 PWM，fr-频率，dc-占空比 */
void ConfigPWM（unsigned int fr， unsigned char dc）{
unsigned int high， low;
unsigned long tmp;
tmp = （11059200/12） / fr; //计算一个周期所需的计数值
high = （tmp*dc） / 100; //计算高电平所需的计数值
low = tmp - high; //计算低电平所需的计数值
high = 65536 - high + 12; //计算高电平的重载值并补偿中断延时
low = 65536 - low + 12;//计算低电平的重载值并补偿中断延时
HighRH = （unsigned char）（high》》8）; //高电平重载值拆分为高低字节
HighRL = （unsigned char）high;
LowRH = （unsigned char）（low》》8）; //低电平重载值拆分为高低字节
LowRL = （unsigned char）low;
TMOD &= 0xF0; //清零 T0 的控制位
TMOD |= 0x01; //配置 T0 为模式 1
