PIC16F15323单片机 （中断与定时器Timer0）

开发环境选择的是 MPLAB X IDE v5.50和 xc8-v2.32-full-install-windows-x64-installer。

1 基本原理

2 实现代码

主要根据FIGURE 25-1 和中断的逻辑框图来编写代码，这样代码的可读性强，也便于理解。但有些寄存器在框图中可能没有说明，所以也需要仔细阅读定时器0的官方文档，即基本原理部分。

/*
 * File:   timer0.c
 * Author: Sure
 *---------------系统功能：
	    中断 定时器0

 * Created on October 21, 2021, 7:48 PM
 */

// PIC16F15323 Configuration Bit Settings
// -----------熔丝配置--------------
// 'C' source line config statements
// CONFIG1
#pragma config FEXTOSC = ECH    // External Oscillator mode selection bits (EC above 8MHz; PFM set to high power)
#pragma config RSTOSC = EXT1X   // Power-up default value for COSC bits (EXTOSC operating per FEXTOSC bits)
#pragma config CLKOUTEN = OFF   // Clock Out Enable bit (CLKOUT function is disabled; i/o or oscillator function on OSC2)
#pragma config CSWEN = OFF       // Clock Switch Enable bit (Writing to NOSC and NDIV is allowed)
#pragma config FCMEN = OFF       // Fail-Safe Clock Monitor Enable bit (FSCM timer enabled)

// CONFIG2
#pragma config MCLRE = OFF       // Master Clear Enable bit (MCLR pin is Master Clear function)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config LPBOREN = OFF    // Low-Power BOR enable bit (ULPBOR disabled)
#pragma config BOREN = OFF       // Brown-out reset enable bits (Brown-out Reset Enabled, SBOREN bit is ignored)
#pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (VBOR) set to 1.9V on LF, and 2.45V on F Devices)
#pragma config ZCD = OFF        // Zero-cross detect disable (Zero-cross detect circuit is disabled at POR.)
#pragma config PPS1WAY = OFF     // Peripheral Pin Select one-way control (The PPSLOCK bit can be cleared and set only once in software)
#pragma config STVREN = OFF      // Stack Overflow/Underflow Reset Enable bit (Stack Overflow or Underflow will cause a reset)

// CONFIG3
#pragma config WDTCPS = WDTCPS_31// WDT Period Select bits (Divider ratio 1:65536; software control of WDTPS)
#pragma config WDTE = OFF        // WDT operating mode (WDT enabled regardless of sleep; SWDTEN ignored)
#pragma config WDTCWS = WDTCWS_7// WDT Window Select bits (window always open (100%); software control; keyed access not required)
#pragma config WDTCCS = SC      // WDT input clock selector (Software Control)

// CONFIG4
#pragma config BBSIZE = BB512   // Boot Block Size Selection bits (512 words boot block size)
#pragma config BBEN = OFF       // Boot Block Enable bit (Boot Block disabled)
#pragma config SAFEN = OFF      // SAF Enable bit (SAF disabled)
#pragma config WRTAPP = OFF     // Application Block Write Protection bit (Application Block not write protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot Block not write protected)
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration Register not write protected)
#pragma config WRTSAF = OFF     // Storage Area Flash Write Protection bit (SAF not write protected)
#pragma config LVP = OFF         // Low Voltage Programming Enable bit (Low Voltage programming enabled. MCLR/Vpp pin function is MCLR.)

// CONFIG5
#pragma config CP = OFF         // UserNVM Program memory code protection bit (UserNVM code protection disabled)

// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.



#include <xc.h>//引用头文件
//#include"delay.h"//调用延时子函数



/*-----------宏定义--------------*/
#define  uint  unsigned int
#define  uchar unsigned char
#define  V0     RA0


uint i;


/*-----------子函数声明--------------*/



/*-----------主函数--------------*/
void main(void)
{
	// The corresponding data direction register is TRISA. 
	// Setting  a TRISA bit (= 1) will make the corresponding PORTA pi an input. 
	// Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output.        
	TRISA=0xfe;			//设置数据方向 RA7-RA1为输入，RA0为输出
    
    
    
    // 1 = Port pin is > VIH，即高电平  ;  0 = Port pin is < VIL ,即低电平
	PORTA=0X00;			//端口赋初值


    
	/********定时器TMR0初始化**********/
    //The T0CS<2:0> bits of the T0CON1 register are used to select the clock source for Timer0. 
    //  Clock Source Selection: 010 = FOSC/4   
	T0CS2=0;				//TMR0时钟源选择位，TMR0的时钟源 选择 内部指令周期（fosc/4）
	T0CS1=1;
	T0CS0=0;


    
    // There are 16 prescaler options for Timer0 ranging in powers of two from 1:1 to
    // 1:32768. The prescaler values are selected using the T0CKPS<3:0> bits of the T0CON1 register.
    T0CKPS3=0;              // 预分频 1:1 ，对应的编码为0000
	T0CKPS2=0;		
	T0CKPS1=0;
	T0CKPS0=0;


    
    // T0ASYNC: TMR0 Input Asynchronization Enable bit
    // 1 = The input to the TMR0 counter is not synchronized to system clocks
    // 0 = The input to the TMR0 counter is synchronized to FOSC/4
    T0ASYNC=0;              // 同步时钟模式
    
    
    
    // T016BIT : Timer0 Operating as 16-bit Timer Select bit
    // 1 = Timer0 is a 16-bit timer.   0 = Timer0 is an 8-bit timer
    T016BIT=1;              // 计数寄存器16位
    
    
    
    // 2The Timer0 interrupt flag bit (TMR0IF) is set when either of the following conditions occur:
    // 8-bit TMR0L matches the TMR0H value.     16-bit TMR0 rolls over from ‘FFFFh’
    
    
    
	// The Timer1 module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and TMR1L)
	// which are readable and writable. 
	//16位计数寄存器给初值，在这里没有考虑中断所造成的时钟延迟13个指令周期
	TMR0H=(65536-100)/256; 	// 定时100us*8(八分频)，计数寄存器就会溢出
	TMR0L=(65536-100)%256; 	


    
    // There are 16 postscaler options for Timer0 ranging from 1:1 to 1:16.
    // The postscaler values are selected using the T0OUTPS<3:0> bits of the T0CON0 register. 	
	T0OUTPS3=0;             // 后分频器  0000 = 1:1 Postscaler
	T0OUTPS2=0;
	T0OUTPS1=0;
	T0OUTPS0=0;
	


	// Timer0 Enable bit.  1 = The module is enabled and operating
	// 0 = The module is disabled and in the lowest power mode
	T0EN=1;                 // 打开定时器0



	// This overflow sets bit TMR0IF(T0IF). 通过T0IF=1，来说明计数寄存器溢出了
	TMR0IF=0;				//TMR0的溢出中断标志位 清零，从而计数寄存器满的时候，T0IF产生一个上升沿。



	//If Timer0 interrupts are enabled (TMR0IE bit of the PIE0 register = 1), the CPU will be interrupted 
	 TMR0IE=1;              // 打开定时器0的使能位



	//******************** 开全局中断设置
	//定时器T0设置了中断允许，此处要开全局中断
	GIE=1;                  // 中断总允许控制位 置一
	


	while(1)                // 死循环，单片机初始化后，就一直运行这个死循环
	{

	}
	
}


/*************中断服务程序***************/
// void __interrupt(irq(TMR0,TMR1),base(0x100)) timerIsr(void)
// 文档里可以查到要用 void __interrupt() ISR(void) 的形式添加中断程序
//void interrupt ISR(void)//PIC单片机的所有中断都是这样一个入口
void __interrupt() ISR(void)//PIC单片机的所有中断都是这样一个入口
{
	// The TMR0 interrupt is generated(T0IF==1) when the TMR0 register overflows from FFFFh to 0000h.
	// 计数器寄存器由全1变为全0的时候，T0IF==1.
	if(TMR0IF==1)			//需要进一步判断是否为T0中断    
	{

		//定时器中断后，要重置初值，以备下次中断
		TMR0H=(65536-100)/256; 	
		TMR0L=(65536-100)%256; 		



		// Bit TMR0IF must be cleared in software by the Timer0 module Interrupt Service Routine
		// before re-enabling this interrupt. 解释了为什么要清零
		//溢出中断标志位清零     只有T0IF出现上升沿，才会产生中断，所以中断发生之后要清零。		
		TMR0IF=0;			
		


		// 执行中断处理程序，也就是中断产生了，我们想要执行什么功能
		if(++i>250)		//2ms中断一次，再计次250次后就是500ms
		{
			i=0;
			V0=!V0;		// 取反  实现一秒的闪烁
		}
		
	}
}