spi_master.c

AVR的SPI的通信例子

#include "SPI_Master.h"


void  SPIInit(void)
{
  volatile INT8U  temp;
  DDRB |= (1<<MOSI)|(1<<SCK)|(1<<SS);    //MISO=input and MOSI,SCK,SS = output
  DDRB &=~(1<<MISO);
  PORTB|= (1<<SCK)|(1<<MOSI)|(1<<SS);
  SPCR  = (1<<SPE)|(1<<MSTR)|(1<<SPR0);                           //SPI允许，主机模式，MSB，不允许SPI中断，极性方式00，1/2系统时钟速率
  SPSR  = 1<<SPI2X;
  temp  = SPSR;
  temp  = SPDR;                            //清空SPI，和中断标志，使SPI空闲
}

void SPIPutChar(INT8U data)
{
  PORTB&=~(1<<SS);
  SPDR=data;
  while(!(SPSR&(1<<SPIF)));
  PORTB|=1<<SS;
}

INT8U SPIGetChar(void)
{
  INT8U data;
  PORTB&=~(1<<SS);
  SPDR=0;
  while(!(SPSR&(1<<SPIF)));
  PORTB|=1<<SS;
  data=SPDR;
  data=SPDR;
  return data;
}
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