STC实验箱4
IAP15W4K58S4
Keil uVision V5.29.0.0
PK51 Prof.Developers Kit Version:9.60.0.0

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硬知识

硬件知识

       摘自《STC15系列单片机器件手册》
       STC15系列部分单片机集成了3路可编程计数器阵列（CCP/PCA）模块（STC15W4K32S4系列单片机只有两路CCP/PCA），可用于软件定时器、外部脉冲的捕捉、高速脉冲输出以及脉宽调制（PWM）输出。
       下表总结了STC15系列单片机内部集成了CCP/PCA/PM功能的单片机型号：

       上表中√表示对应的系列有相应的功能。

CCP/PWM/PCA模块的结构

       STC15系列部分单片机有3路可编程计数器阵列CCP/PCA/PWM（通过AUXR1/P_SW1寄存器可以设置CCP/PCA/PWM从P1口切换到P2口切换到P3口）。
       PCA含有一个特殊的16位定时器，有3个16位的捕获/比较模块与之相连，如下图所示。

       每个模块可编程工作在4种模式下：上升/下降沿捕获、软件定时器、高速脉冲输出或可调制脉冲输出。
       16位PCA定时器/计数器是3个模块的公共时间基准，其结构如下图所示。

软件知识

       摘自《STC库函数使用参考》

PCA初始化函数

PCA_Init

PCA_id：选择要初始化的PCA通道：
PCA_InitTypeDef的定义见于文件"PCA.H".

typedef struct
{u8 PCA_IoUse;u8 PCA_Clock; u8 PCA_Mode; u8 PCA_PWM_Wide;u8 PCA_Interrupt_Mode; u8 PCA_Polity;u16 PCA_Value;
} PCA_InitTypeDef;

PCA_IoUse：选择PCA使用的IO：初始化PCA_Counter时的取值，初始化PCA0~PCA2时忽略

PCA_Clock：选择PCA使用的时钟：初始化PCA_Counter时的取值，初始化PCA0~PCA2时忽略
PCA_Mode：设置PCA通道的工作模式：初始化PCA0~PCA2时的取值，初始化PCA_Counter时忽略

PCA_PWM_Wide：设置PCA通道工作于PWM模式时的PWM宽度：初始化PCA0~PCA2工作于PWM模式时的取值，初始化PCA_Counter时或PCA通道其它模式时忽略

PCA_Interrupt_Mode：中断允许或禁止：初始化PCA0~PCA2时的取值，初始化PCA_Counter时忽略
注意：上面的参数可以做如下组合：

PCA_InitStructure.PCA_Interrupt_Mode = PCA_Fall_Active | ENABLE; //下降沿中断，允许中断。
PCA_InitStructure.PCA_Interrupt_Mode = PCA_Rise_Active | ENABLE; //上升沿中断，允许中断。
PCA_InitStructure.PCA_Interrupt_Mode = PCA_Rise_Active | PCA_Fall_Active | ENABLE; //上升沿、下降沿中断，允许中断。

如果后面使用了| DISABLE，则中断被禁止。

PCA_Polity：中断的优先级：初始化PCA_Counter时的取值，初始化PCA0~PCA2时忽略
PCA_Value：设置PCA通道的初值。初始化PCA0~PCA2时的取值，初始化PCA_Counter时忽略

PWM更新占空比函数

UpdatePwm

测试程序

PWM模式产生PWM信号

PCA.c里的UpdatePwm函数默认是被注释掉的，需要解除注释：

main.c

#include "./Drivers/config.h"
#include "./Drivers/delay.h"#include "./Drivers/GPIO.h"
#include "./Drivers/PCA.h"void GPIO_config(void)
{GPIO_InitTypeDef GPIO_InitStructure;					//结构定义GPIO_InitStructure.Mode = GPIO_OUT_PP;					//指定IO的输入或输出方式,GPIO_PullUp,GPIO_HighZ,GPIO_OUT_OD,GPIO_OUT_PPGPIO_InitStructure.Pin  = GPIO_Pin_5 | GPIO_Pin_6;		//指定要初始化的IO, 或操作GPIO_Inilize(GPIO_P2, &GPIO_InitStructure);				//P2.5、P2.6初始化为推挽输出
}void PCA_config(void)
{PCA_InitTypeDef PCA_InitStructure;PCA_InitStructure.PCA_Mode     = PCA_Mode_PWM;		//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = PCA_PWM_8bit;		//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = DISABLE;		//PCA_Rise_Active, PCA_Fall_Active, ENABLE, DISABLEPCA_InitStructure.PCA_Value    = (u16)((1 << 8) * (1 - 0.5));//对于软件定时, 为匹配比较值PCA_Init(PCA0,&PCA_InitStructure);PCA_InitStructure.PCA_Mode     = PCA_Mode_PWM;		//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = PCA_PWM_7bit;		//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = DISABLE;		//PCA_Rise_Active, PCA_Fall_Active, ENABLE, DISABLEPCA_InitStructure.PCA_Value    = (u16)((1 << 7) * (1 - 0.5));//对于软件定时, 为匹配比较值PCA_Init(PCA1,&PCA_InitStructure);PCA_InitStructure.PCA_Clock    = PCA_Clock_1T;		//PCA_Clock_1T, PCA_Clock_2T, PCA_Clock_4T, PCA_Clock_6T, PCA_Clock_8T, PCA_Clock_12T, PCA_Clock_Timer0_OF, PCA_Clock_ECIPCA_InitStructure.PCA_IoUse    = PCA_P24_P25_P26_P27;//PCA_P12_P11_P10_P37, PCA_P34_P35_P36_P37, PCA_P24_P25_P26_P27PCA_InitStructure.PCA_Interrupt_Mode = DISABLE;		//ENABLE, DISABLEPCA_InitStructure.PCA_Polity   = PolityHigh;		//优先级设置	PolityHigh,PolityLowPCA_Init(PCA_Counter,&PCA_InitStructure);
}void main(void)
{GPIO_config();PCA_config();UpdatePwm(PCA0, (1 << 8) * (1 - 0.75));UpdatePwm(PCA1, (1 << 7) * (1 - 0.25));while(1){}
}

实验现象

PWM频率 = PCA时钟频率 / $2^{PWM位数}$

$30MHz/1/2^8=117187.5Hz$

$30MHz/1/2^7=234375Hz$

16位软件定时器模式模式产生PWM信号

PWM频率 = PCA时钟频率 / PWMx_DUTY

修改PCA.h中的PWMx_DUTY

修改PCA_Handler内的对应引脚

//========================================================================
// 函数: void	PCA_Handler (void) interrupt PCA_VECTOR
// 描述: PCA中断处理程序.
// 参数: None
// 返回: none.
// 版本: V1.0, 2012-11-22
//========================================================================
void	PCA_Handler (void) interrupt PCA_VECTOR
{if(CCF0)		//PCA模块0中断{CCF0 = 0;		//清PCA模块0中断标志if(P25)	CCAP0_tmp += PCA_Timer0;	//输出为高电平，则给影射寄存器装载高电平时间长度else	CCAP0_tmp += PWM0_low;	//输出为低电平，则给影射寄存器装载低电平时间长度CCAP0L = (u8)CCAP0_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP0H = (u8)(CCAP0_tmp >> 8);	//后写CCAP0H}if(CCF1)	//PCA模块1中断{CCF1 = 0;		//清PCA模块1中断标志if(P26)	CCAP1_tmp += PCA_Timer1;	//输出为高电平，则给影射寄存器装载高电平时间长度else	CCAP1_tmp += PWM1_low;	//输出为低电平，则给影射寄存器装载低电平时间长度CCAP1L = (u8)CCAP1_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP1H = (u8)(CCAP1_tmp >> 8);	//后写CCAP0H}if(CCF2)	//PCA模块2中断{CCF2 = 0;		//清PCA模块1中断标志if(P27)	CCAP2_tmp += PCA_Timer2;	//输出为高电平，则给影射寄存器装载高电平时间长度else	CCAP2_tmp += PWM2_low;	//输出为低电平，则给影射寄存器装载低电平时间长度CCAP2L = (u8)CCAP2_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP2H = (u8)(CCAP2_tmp >> 8);	//后写CCAP0H}if(CF)	//PCA溢出中断{CF = 0;			//清PCA溢出中断标志}}

main.c

#include "./Drivers/config.h"
#include "./Drivers/delay.h"#include "./Drivers/GPIO.h"
#include "./Drivers/PCA.h"void GPIO_config(void)
{GPIO_InitTypeDef GPIO_InitStructure;					//结构定义GPIO_InitStructure.Mode = GPIO_OUT_PP;					//指定IO的输入或输出方式,GPIO_PullUp,GPIO_HighZ,GPIO_OUT_OD,GPIO_OUT_PPGPIO_InitStructure.Pin  = GPIO_Pin_5 | GPIO_Pin_6;		//指定要初始化的IO, 或操作GPIO_Inilize(GPIO_P2, &GPIO_InitStructure);				//P2.5、P2.6初始化为推挽输出
}void PCA_config(void)
{PCA_InitTypeDef PCA_InitStructure;PCA_InitStructure.PCA_Mode     = PCA_Mode_HighPulseOutput;	//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = 0;							//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = ENABLE;				//PCA_Rise_Active, PCA_Fall_Active, ENABLE, DISABLEPCA_InitStructure.PCA_Value    = 65535;						//对于软件定时, 为匹配比较值PCA_Init(PCA0,&PCA_InitStructure);PCA_InitStructure.PCA_Mode     = PCA_Mode_HighPulseOutput;	//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = 0;							//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = ENABLE;				//PCA_Rise_Active, PCA_Fall_Active, ENABLE, DISABLEPCA_InitStructure.PCA_Value    = 65535;						//对于软件定时, 为匹配比较值PCA_Init(PCA1,&PCA_InitStructure);PCA_InitStructure.PCA_Clock    = PCA_Clock_12T;				//PCA_Clock_1T, PCA_Clock_2T, PCA_Clock_4T, PCA_Clock_6T, PCA_Clock_8T, PCA_Clock_12T, PCA_Clock_Timer0_OF, PCA_Clock_ECIPCA_InitStructure.PCA_IoUse    = PCA_P24_P25_P26_P27;		//PCA_P12_P11_P10_P37, PCA_P34_P35_P36_P37, PCA_P24_P25_P26_P27PCA_InitStructure.PCA_Interrupt_Mode = DISABLE;				//ENABLE, DISABLEPCA_InitStructure.PCA_Polity   = PolityHigh;				//优先级设置	PolityHigh,PolityLowPCA_Init(PCA_Counter, &PCA_InitStructure);
}void main(void)
{GPIO_config();PCA_config();PWMn_Update(PCA0, (u16)(PWM0_DUTY * 0.75));PWMn_Update(PCA1, (u16)(PWM1_DUTY * 0.25));EA = 1;while(1){}
}

实验现象

$30MHz/12/50000=50Hz$

捕获模式测量周期长度

修改PCA.c内的PCA_Handler

//========================================================================
// 函数: void	PCA_Handler (void) interrupt PCA_VECTOR
// 描述: PCA中断处理程序.
// 参数: None
// 返回: none.
// 版本: V1.0, 2012-11-22
//========================================================================
void	PCA_Handler (void) interrupt PCA_VECTOR
{if(CCF0)		//PCA模块0中断{CCF0 = 0;		//清PCA模块0中断标志if(P25)	CCAP0_tmp += PCA_Timer0;	//输出为高电平，则给影射寄存器装载高电平时间长度else	CCAP0_tmp += PWM0_low;	//输出为低电平，则给影射寄存器装载低电平时间长度CCAP0L = (u8)CCAP0_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP0H = (u8)(CCAP0_tmp >> 8);	//后写CCAP0H}if(CCF1)	//PCA模块1中断{CCF1 = 0;		//清PCA模块1中断标志if(PCA1_mode >= PCA_Mode_SoftTimer)		//PCA_Mode_SoftTimer and PCA_Mode_HighPulseOutput{CCAP1_tmp += PCA_Timer1;CCAP1L = (u8)CCAP1_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP1H = (u8)(CCAP1_tmp >> 8);	//后写CCAP0H}else if(PCA1_mode == PCA_Mode_Capture){CCAP1_tmp = CCAP1H;	//读CCAP1HCCAP1_tmp = (CCAP1_tmp << 8) + CCAP1L;B_Capture1 = 1;}}if(CCF2)	//PCA模块2中断{CCF2 = 0;		//清PCA模块1中断标志if(P27)	CCAP2_tmp += PCA_Timer2;	//输出为高电平，则给影射寄存器装载高电平时间长度else	CCAP2_tmp += PWM2_low;	//输出为低电平，则给影射寄存器装载低电平时间长度CCAP2L = (u8)CCAP2_tmp;			//将影射寄存器写入捕获寄存器，先写CCAP0LCCAP2H = (u8)(CCAP2_tmp >> 8);	//后写CCAP0H}if(CF)	//PCA溢出中断{CF = 0;			//清PCA溢出中断标志}}

main.c

#include "./Drivers/config.h"
#include "./Drivers/delay.h"#include "./Drivers/GPIO.h"
#include "./Drivers/PCA.h"#include "./Drivers/soft_UART.h"
#include <stdio.h>char putchar(char Char)
{TxSend(Char);return Char;
}void GPIO_config(void)
{GPIO_InitTypeDef GPIO_InitStructure;					//结构定义GPIO_InitStructure.Mode = GPIO_OUT_PP;					//指定IO的输入或输出方式,GPIO_PullUp,GPIO_HighZ,GPIO_OUT_OD,GPIO_OUT_PPGPIO_InitStructure.Pin  = GPIO_Pin_5;					//指定要初始化的IO, 或操作GPIO_Inilize(GPIO_P2, &GPIO_InitStructure);				//P2.5初始化为推挽输出
}void PCA_config(void)
{PCA_InitTypeDef PCA_InitStructure;PCA_InitStructure.PCA_Mode     = PCA_Mode_HighPulseOutput;	//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = 0;							//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = ENABLE;				//PCA_Rise_Active, PCA_Fall_Active, ENABLE, DISABLEPCA_InitStructure.PCA_Value    = 65535;						//对于软件定时, 为匹配比较值PCA_Init(PCA0,&PCA_InitStructure);PCA_InitStructure.PCA_Mode     = PCA_Mode_Capture;	//PCA_Mode_PWM, PCA_Mode_Capture, PCA_Mode_SoftTimer, PCA_Mode_HighPulseOutputPCA_InitStructure.PCA_PWM_Wide = 0;					//PCA_PWM_8bit, PCA_PWM_7bit, PCA_PWM_6bitPCA_InitStructure.PCA_Interrupt_Mode = PCA_Fall_Active | ENABLE;	//(PCA_Rise_Active, PCA_Fall_Active) or (ENABLE, DISABLE)PCA_InitStructure.PCA_Value    = 0;					//对于捕捉, 这个值没意义PCA_Init(PCA1,&PCA_InitStructure);PCA_InitStructure.PCA_Clock    = PCA_Clock_12T;				//PCA_Clock_1T, PCA_Clock_2T, PCA_Clock_4T, PCA_Clock_6T, PCA_Clock_8T, PCA_Clock_12T, PCA_Clock_Timer0_OF, PCA_Clock_ECIPCA_InitStructure.PCA_IoUse    = PCA_P24_P25_P26_P27;		//PCA_P12_P11_P10_P37, PCA_P34_P35_P36_P37, PCA_P24_P25_P26_P27PCA_InitStructure.PCA_Interrupt_Mode = DISABLE;				//ENABLE, DISABLEPCA_InitStructure.PCA_Polity   = PolityHigh;				//优先级设置	PolityHigh,PolityLowPCA_Init(PCA_Counter, &PCA_InitStructure);
}u16	Cap_time;	//上一次捕捉时间void main(void)
{u16 j;Cap_time = 0;GPIO_config();PCA_config();PWMn_Update(PCA0, (u16)(PWM0_DUTY * 0.75));EA = 1;while(1){if(B_Capture1){B_Capture1 = 0;j = CCAP1_tmp - Cap_time;	//计算时间差Cap_time = CCAP1_tmp;printf("%d us\r\n", (int)(j * 12. / 30));}delay_ms(1);}
}

实验现象