P_SW2寄存器的最高位EAXFR 是扩展SFR访问控制使能
如下特殊功能寄存器位于扩展 RAM 区域 访问这些寄存器,需先将 P_SW2 的 BIT7(EAXFR) 设置为 1,才可正常读写
- #include "reg51.h"
- #include "intrins.h"
- //测试工作频率为11.0592MHz
- sfr P_SW2 = 0xba;
- sfr PWMCFG = 0xf1;
- sfr PWMIF = 0xf6;
- sfr PWMFDCR = 0xf7;
- sfr PWMCR = 0xfe;
- #define PWMC (*(unsigned int volatile xdata *)0xfff0)
- #define PWMCKS (*(unsigned char volatile xdata *)0xfff2)
- #define TADCP (*(unsigned int volatile xdata *)0xfff3)
- #define PWM0T1 (*(unsigned int volatile xdata *)0xff00)
- #define PWM0T2 (*(unsigned int volatile xdata *)0xff02)
- #define PWM0CR (*(unsigned char volatile xdata *)0xff04)
- #define PWM0HLD (*(unsigned char volatile xdata *)0xff05)
- #define PWM1T1 (*(unsigned int volatile xdata *)0xff10)
- #define PWM1T2 (*(unsigned int volatile xdata *)0xff12)
- #define PWM1CR (*(unsigned char volatile xdata *)0xff14)
- #define PWM1HLD (*(unsigned char volatile xdata *)0xff15)
- #define PWM2T1 (*(unsigned int volatile xdata *)0xff20)
- #define PWM2T2 (*(unsigned int volatile xdata *)0xff22)
- #define PWM2CR (*(unsigned char volatile xdata *)0xff24)
- #define PWM2HLD (*(unsigned char volatile xdata *)0xff25)
- #define PWM3T1 (*(unsigned int volatile xdata *)0xff30)
- #define PWM3T2 (*(unsigned int volatile xdata *)0xff32)
- #define PWM3CR (*(unsigned char volatile xdata *)0xff34)
- #define PWM3HLD (*(unsigned char volatile xdata *)0xff35)
- #define PWM4T1 (*(unsigned int volatile xdata *)0xff40)
- #define PWM4T2 (*(unsigned int volatile xdata *)0xff42)
- #define PWM4CR (*(unsigned char volatile xdata *)0xff44)
- #define PWM4HLD (*(unsigned char volatile xdata *)0xff45)
- #define PWM5T1 (*(unsigned int volatile xdata *)0xff50)
- #define PWM5T2 (*(unsigned int volatile xdata *)0xff52)
- #define PWM5CR (*(unsigned char volatile xdata *)0xff54)
- #define PWM5HLD (*(unsigned char volatile xdata *)0xff55)
- #define PWM6T1 (*(unsigned int volatile xdata *)0xff60)
- #define PWM6T2 (*(unsigned int volatile xdata *)0xff62)
- #define PWM6CR (*(unsigned char volatile xdata *)0xff64)
- #define PWM6HLD (*(unsigned char volatile xdata *)0xff65)
- #define PWM7T1 (*(unsigned int volatile xdata *)0xff70)
- #define PWM7T2 (*(unsigned int volatile xdata *)0xff72)
- #define PWM7CR (*(unsigned char volatile xdata *)0xff74)
- #define PWM7HLD (*(unsigned char volatile xdata *)0xff75)
- void main()
- {
- P_SW2 = 0x80; //将P_SW2寄存器的最高位EAXFR置1,访问XSFR
- PWMCKS = 0x00; // PWM时钟为系统时钟
- PWMC = 0x1000; //设置PWM周期为1000H个PWM时钟
- PWM0T1= 0x0100; //在计数值为100H地方输出低电平
- PWM0T2= 0x0500; //在计数值为500H地方输出高电平
- PWM0CR= 0x80; //使能PWM0输出
- P_SW2 = 0x00;
- PWMCR = 0x80; //启动PWM模块
- while (1);
- }
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