MC9RS08KA4下的定时器模拟UART例子程序

发表于 2012/8/2 15:53:39 阅读（1773）

RS系列单片机既不支持中断，又没有UART串口。然而有人希望用来也串口通信。用定时器的输出比较功能可以在比较准的时间翻转引脚，用查询方式查到输出比较中断标识后，可以把下一次引脚状态写入定时器……，下面给出一段例程，程序采用TPMCH0,PTA0引脚，软件模拟成UART发送脚，本程序在MC9RS08KA4下调试通过。下面是完整代码：

#include <hidef.h> /* for EnableInterrupts macro */
#include "derivative.h" /* include peripheral declarations */
#define CPU_CLK 16000000
#define BUS_CLK (CPU_CLK/2)
#define BUARD_RATE 1200
#define BIT_TIME ((BUS_CLK+(BUARD_RATE/2))/BUARD_RATE)//16MHz cpu频率下是6667

//本程序采用TPMCH0,PTA0引脚，软件模拟成UART发送脚
void putchar(char c)
{
unsigned char cnt;
TPMCNTL = 0;//计数清0
TPMC0V = 100;//匹配
TPMC0SC = 0x58;//匹配时输出0,发送起始位
//TPMSC = 0x08;
TPMC0SC_CH0F = 0;
//等待上一次匹配
while(TPMC0SC_CH0F != 1)//等待定时器输出比较中断标识
{
     __RESET_WATCHDOG(); // feeds the dog
}
TPMC0V += BIT_TIME;
// 发送8个数据位
for(cnt=0 ; cnt<8 ;cnt++)
{
    if( (c&1) == 0)
    {
      TPMC0SC = 0x58;//匹配时输出0
    }
    else
    {
      TPMC0SC = 0x5C;//匹配时输出1
    }
    c >>= 1;;
    TPMC0SC_CH0F = 0;
    while(TPMC0SC_CH0F != 1)//等待定时器输出比较中断标识
    {
       __RESET_WATCHDOG(); // feeds the dog
    }
    TPMC0V += BIT_TIME;
}
TPMC0SC = 0x5C;
TPMC0SC_CH0F = 0;
while(TPMC0SC_CH0F != 1)//等待定时器输出比较中断标识
{
     __RESET_WATCHDOG(); // feeds the dog
}
//TPMSC_TOF = 0;
TPMC0SC = 0x1C;
//TPMSC = 0;//关闭定时器
}

void InitTPM()
{
TPMC0SC = 0x1C;//匹配时输出1
TPMC0V = 0;//立即匹配
TPMSC = 0x08;
TPMCNTL = 0;//计数清0
}
void ICS_Init()
{
if (*(unsigned char* __paged)CONVERT_TO_PAGED(0x3FFA) != 0xFF)
{ // Test if the device trim value is stored on the specified address
ICSTRM = *(unsigned char* __paged)CONVERT_TO_PAGED(0x3FFA); // Initialize ICSTRM register from a non volatile memory
ICSSC = *(unsigned char* __paged)CONVERT_TO_PAGED(0x3FFB); // Initialize ICSSC register from a non volatile memory
}

ICSC1 = 0x06;//ICSC1: CLKS=0,RDIV=0,IREFS=1,IRCLKEN=1,IREFSTEN=0
ICSC2 = 0x00;//ICSC2: BDIV=0,RANGE=0,HGO=0,LP=0,EREFS=0,ERCLKEN=0,EREFSTEN=0

}
void delay()
{
unsigned int cnt;
for(cnt=0 ; cnt<6000 ; cnt++)
{
__RESET_WATCHDOG();
}
}
void main(void) {

EnableInterrupts; /* enable interrupts */
/* include your code here */
ICS_Init();
InitTPM();
for(;;) {
    putchar(0x33);
    delay();
    __RESET_WATCHDOG(); /* feeds the dog */
} /* loop forever */
/* please make sure that you never leave main */
}

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