spi_slave

用ICC编写的程序包括SPI

#pragma interrupt_handler spi_stc_isr:11
#include "SPI_slave.h"
unsigned char SPI_rx_buff[SPI_size];  
unsigned char SPI_tx_buff[SPI_size];  
unsigned char rx_wr_index,rx_rd_index,rx_counter,rx_buffer_overflow;  
unsigned char tx_wr_index,tx_rd_index,tx_counter;

unsigned char CntByte=0;
unsigned char frame[3];
unsigned char temp;
//数据包格式：第一个字节是表示是命令还是数据包：0xaa是命令包
//											    0x55是数据包
//			  第二，三个字节是表示什么命令及数据

void spi_stc_isr(void)
{
  temp=SPDR;
  if(CntByte<3)
  frame[CntByte]=temp;
  else
  {
     i=0;
	 switch(frame[0])
	   case 0xaa:
	        {
			switch(frame[1])
			case 0x01:
			  putSPIchar(0x55);
			  putSPIchar(*(unsigned char*)(qep_cnt));
			  putSPIchar(*((unsigned char*)(qep_cnt)+1));
			  break;
			case 0x02:
			  putSPIchar(0x55);
			  putSPIchar(*(unsigned char*)(qep_cnt+1));
			  putSPIchar(*((unsigned char*)(qep_cnt+1)+1));
			  break;
			 default:
			  break;
			}
	   case 0x55:
	   		pwm_vaule[0]=frame[0];
			pwm_vaule[1]=frame[1];
			break;	
	   case 0x00:
  	   		break;
	   default:
	        break;
 }
 SPI_rx_buff[rx_wr_index] = temp;
 if (++rx_wr_index == SPI_size) rx_wr_index = 0;    //放入接收缓冲区，并调整队列指针  
  if (++rx_counter == SPI_size)  
  {  
    rx_counter = 0;  
    rx_buffer_overflow = 1;  
  }  
  if (tx_counter)        //如果发送缓冲区中有待发的数据  
  {  
     --tx_counter;  
     SPDR = SPI_tx_buff[tx_rd_index]; //发送一个字节数据，并调整指针  
     SPI_ok=0;
	 if (++tx_rd_index == SPI_size) tx_rd_index = 0;  
  }
	
}



void putSPIchar(char c)  
{  
  while (tx_counter == SPI_size);//发送缓冲区满，等待    
    SPI_tx_buff[tx_wr_index] = c;    //将数据放入发送缓冲区排队  
    if (++tx_wr_index == SPI_size) tx_wr_index = 0;    //调整指针  
    ++tx_counter;   
}  


unsigned char getSPIchar(void)  
{  
  unsigned char data;  
  while (rx_counter == 0);     //无接收数据，等待  
  data = SPI_rx_buff[rx_rd_index];    //从接收缓冲区取出一个SPI收到的数据  
  if (++rx_rd_index == SPI_size) rx_rd_index = 0;    //调整指针  
  CLI();  
  --rx_counter;  
  SEI();  
  return data;  
}


//从机模式
void spi_init(void)  
{  
  unsigned char temp;  
  		   		    //MISO=ouput and MOSI,SCK,SS = input  
  DDRB |=BIT(MISO);
  PORTB |=BIT(MISO);    //MISO上拉电阻有效   
  DDRB&=~BIT(SS);
  SPCR = 0xC7;    //SPI允许，从机模式，MSB，允许SPI中断  极性方式01，1/4系统时钟速率  
  SPSR = 0x00;  
  temp = SPSR;  
  temp = SPDR;    //清空SPI，和中断标志，使SPI空闲
  SPI_ok=1;
  SPI_datain=0;  
}