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发表于 2019-9-3 19:30:49
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/* 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 = 0x11; //配置T0为模式1
TH0 = HighRH; //加载T0重载值
TL0 = HighRL;
ET0 = 1; //使能T0中断
TR0 = 1; //启动T0
PWMOUT = 1; //输出高电平
PWMOUT2 = 0; //输出低电平
}
/* T0中断服务函数,产生PWM输出 */
void InterruptTimer0() interrupt 1
{
if ((PWMOUT == 1)||(PWMOUT2==0)) //当前输出为高电平时,装载低电平值并输出低电平
{
TH0 = LowRH;
TL0 = LowRL;
PWMOUT = 0;
PWMOUT2=1;
}
else //当前输出为低电平时,装载高电平值并输出高电平
{
TH0 = HighRH;
TL0 = HighRL;
PWMOUT = 1;
}
} |
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