STC12C2052PWM问题

#include<reg52.H>
#define uint unsigned int
#define uchar unsigned char
sfr CCON=0xD8;
sfr CMOD=0xD9;
sfr CCAP0L=0xEA;
sfr CCAP0H=0xFA;
sfr CCAPM0=0xDA;
sfr CCAPM1=0xDB;
sbit CR=0xDE;
sfr CL=0xE9;
sfr CH=0xF9;
uchar a;
sbit key1=P1^0;
sbit key2=P1^1;
sbit key3=P1^2;
sbit key4=P1^7;
void delay(unsigned int cnt)
{
while(--cnt);
}
void PWM_init();
void PWM0_set(a);
void main()
{
PWM_init();
while(1)
{
a=0;
if(key1==0)
{
delay(1500);
if(key1==0)
{
a=10;
PWM0_set(a);
}
}
if(key2==0)
{
delay(1500);
if(key2==0)
{
a=30;
PWM0_set(a);
}
}
if(key3==0)
{
delay(1500);
if(key3==0)
{
a=70;
PWM0_set(a);
}
}
if(key4==0)
{
delay(1500);
if(key4==0)
{
a=250;
PWM0_set(a);
}
}
}
}
void PWM_init()
{
CMOD=0x02;
CL=0x00;
CH=0x00;
CCAPM0=0x42;
CCAP0L=0x00;
CCAP0H=0x00;
CR=1;
}
void PWM0_set(a)
{
CCAP0L=a;
CCAP0H=a;
}
PWM0脚没有任何反应，请问大侠我程序错哪了？