初学者最重要的就是学会看数据手册
给你一个示例参考
- /*---------------------------------------------------------------------*/
- /* --- STC MCU Limited ------------------------------------------------*/
- /* --- STC 1T Series MCU Demo Programme -------------------------------*/
- /* 如果要在程序中使用此代码,请在程序中注明使用了STC的资料及程序 */
- /*---------------------------------------------------------------------*/
- /************* 功能说明 **************
- 使用Timer0模拟16通道PWM驱动程序。
- 输出为 P1.0 ~ P1.7, P2.0 ~ P2.7, 对应 PWM0 ~ PWM15.
- 定时器中断频率一般不要超过100KHZ, 留足够的时间给别的程序运行.
- 本例子使用11.0592MHZ时钟, 25K的中断频率, 250级PWM, 周期为10ms.
- 中断里处理的时间不超过6us, 占CPU时间大约为15%.
- ******************************************/
- #include <reg52.h>
- #define MAIN_Fosc 11059200UL //定义主时钟
- #define Timer0_Rate 25000 //中断频率
- typedef unsigned char u8;
- typedef unsigned int u16;
- typedef unsigned long u32;
- sfr AUXR = 0x8E;
- sfr P1M1 = 0x91; //PxM1.n,PxM0.n =00--->Standard, 01--->push-pull
- sfr P1M0 = 0x92; // =10--->pure input, 11--->open drain
- sfr P0M1 = 0x93;
- sfr P0M0 = 0x94;
- sfr P2M1 = 0x95;
- sfr P2M0 = 0x96;
- sfr P3M1 = 0xB1;
- sfr P3M0 = 0xB2;
- sfr P4M1 = 0xB3;
- sfr P4M0 = 0xB4;
- sfr P5M1 = 0xC9;
- sfr P5M0 = 0xCA;
- sfr P6M1 = 0xCB;
- sfr P6M0 = 0xCC;
- sfr P7M1 = 0xE1;
- sfr P7M0 = 0xE2;
- #define Timer0_Reload (65536UL -(MAIN_Fosc / Timer0_Rate)) //Timer 0 重装值
- //************** PWM8 变量和常量以及IO口定义 ***************
- //******************** 8通道8 bit 软PWM ********************
- #define PWM_DUTY_MAX 250 // 0~255 PWM周期, 最大255
- #define PWM_ON 1 // 定义占空比的电平, 1 或 0
- #define PWM_OFF (!PWM_ON)
- #define PWM_ALL_ON (0xff * PWM_ON)
- u8 bdata PWM_temp1,PWM_temp2; //影射一个RAM，可位寻址，输出时同步刷新
- sbit P_PWM0 = PWM_temp1^0; // 定义影射RAM每位对应的IO
- sbit P_PWM1 = PWM_temp1^1;
- sbit P_PWM2 = PWM_temp1^2;
- sbit P_PWM3 = PWM_temp1^3;
- sbit P_PWM4 = PWM_temp1^4;
- sbit P_PWM5 = PWM_temp1^5;
- sbit P_PWM6 = PWM_temp1^6;
- sbit P_PWM7 = PWM_temp1^7;
- sbit P_PWM8 = PWM_temp2^0;
- sbit P_PWM9 = PWM_temp2^1;
- sbit P_PWM10 = PWM_temp2^2;
- sbit P_PWM11 = PWM_temp2^3;
- sbit P_PWM12 = PWM_temp2^4;
- sbit P_PWM13 = PWM_temp2^5;
- sbit P_PWM14 = PWM_temp2^6;
- sbit P_PWM15 = PWM_temp2^7;
- u8 pwm_duty; //周期计数值
- u8 pwm[16]; //pwm0~pwm15 为0至15路PWM的宽度值
- bit B_1ms;
- u8 cnt_1ms;
- u8 cnt_20ms;
- /**********************************************/
- void main(void)
- {
- u8 i;
-
- P0M0 = 0x00;
- P0M1 = 0x00;
- P1M0 = 0x00;
- P1M1 = 0x00;
- P2M0 = 0x00;
- P2M1 = 0x00;
- P3M0 = 0x00;
- P3M1 = 0x00;
- P4M0 = 0x00;
- P4M1 = 0x00;
- P5M0 = 0x00;
- P5M1 = 0x00;
- P6M0 = 0x00;
- P6M1 = 0x00;
- P7M0 = 0x00;
- P7M1 = 0x00;
- AUXR |= (1<<7); // Timer0 set as 1T mode
- TMOD &= ~(1<<2); // Timer0 set as Timer
- TMOD &= ~0x03; // Timer0 set as 16 bits Auto Reload
- TH0 = Timer0_Reload / 256; //Timer0 Load
- TL0 = Timer0_Reload % 256;
- ET0 = 1; //Timer0 Interrupt Enable
- PT0 = 1; //高优先级
- TR0 = 1; //Timer0 Run
- EA = 1; //打开总中断
- cnt_1ms = Timer0_Rate / 1000; //1ms计数
- cnt_20ms = 20;
-
- for(i=0; i<16; i++) pwm[i] = i * 15 + 15; //给PWM一个初值
-
- while(1)
- {
- if(B_1ms) //1ms到
- {
- B_1ms = 0;
- if(--cnt_20ms == 0) //PWM 20ms改变一阶
- {
- cnt_20ms = 20;
- for(i=0; i<16; i++) pwm[i]++;
- }
- }
- }
- }
- /********************** Timer0 1ms中断函数 ************************/
- void timer0 (void) interrupt 1
- {
- P1 = PWM_temp1; //影射RAM输出到实际的PWM端口
- P2 = PWM_temp2;
-
- if(++pwm_duty == PWM_DUTY_MAX) //PWM周期结束，重新开始新的周期
- {
- pwm_duty = 0;
- PWM_temp1 = PWM_ALL_ON;
- PWM_temp2 = PWM_ALL_ON;
- }
- ACC = pwm_duty;
- if(ACC == pwm[0]) P_PWM0 = PWM_OFF; //判断PWM占空比是否结束
- if(ACC == pwm[1]) P_PWM1 = PWM_OFF;
- if(ACC == pwm[2]) P_PWM2 = PWM_OFF;
- if(ACC == pwm[3]) P_PWM3 = PWM_OFF;
- if(ACC == pwm[4]) P_PWM4 = PWM_OFF;
- if(ACC == pwm[5]) P_PWM5 = PWM_OFF;
- if(ACC == pwm[6]) P_PWM6 = PWM_OFF;
- if(ACC == pwm[7]) P_PWM7 = PWM_OFF;
- if(ACC == pwm[8]) P_PWM8 = PWM_OFF;
- if(ACC == pwm[9]) P_PWM9 = PWM_OFF;
- if(ACC == pwm[10]) P_PWM10 = PWM_OFF;
- if(ACC == pwm[11]) P_PWM11 = PWM_OFF;
- if(ACC == pwm[12]) P_PWM12 = PWM_OFF;
- if(ACC == pwm[13]) P_PWM13 = PWM_OFF;
- if(ACC == pwm[14]) P_PWM14 = PWM_OFF;
- if(ACC == pwm[15]) P_PWM15 = PWM_OFF;
- if(--cnt_1ms == 0)
- {
- cnt_1ms = Timer0_Rate / 1000;
- B_1ms = 1; // 1ms标志
- }
- }
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