spi通讯例程.txt

学习AVR单片机的基础实验程序 适合初学者学习提高

#define ENABLE_BIT_DEFINITIONS
#include "iom64.h" 
#define SPIF 7
#define SPE 6
#define MSTR 4
#define SPR1 1
#define SPR0 0
#define SS 0
#define CPOL 3


void delay_ms(int time)
{
 int i;
 for(;time>0;time--)
  for(i=0;i<1000;i++);
}

SPI_MasterInit()
{
  DDRB |= (1<<PB1) | (1<<PB2);		/* 设置MOSI 和SCK 为输出，其他为输入 */
  SPCR = (1<<SPE) | (1<<MSTR)| (1<<SPR1) | (1<<SPR0);
}

void SPI_MasterTransmit(unsigned char j) 
{
	SPDR = j;							/* 启动数据传输 */
	while (!(SPSR & (1<<SPIF)));	/* 等待传输结束 */
}




void main(void) 
{

	DDRB = 0x0F;					/*PB口设置为输出*/
        PORTB=0x01;                                     /*置片选信号为高*/
	SPI_MasterInit();
	
	while (1) 
	{  
          	PORTB&=~(1<<SS);	
                SPI_MasterTransmit(0x00);
                SPI_MasterTransmit(0x00);
                PORTB|=(1<<SS);
                 delay_ms(2000);
               
                 PORTB&=~(1<<SS);
                SPI_MasterTransmit(0x40);
                SPI_MasterTransmit(0x00);
               PORTB|=(1<<SS);
                delay_ms(2000);
                             
                PORTB&=~(1<<SS);
                SPI_MasterTransmit(0x50);
                SPI_MasterTransmit(0x00);
               PORTB|=(1<<SS);
                delay_ms(2000);
                
                PORTB&=~(1<<SS);
                SPI_MasterTransmit(0x60);
                SPI_MasterTransmit(0x00);
               PORTB|=(1<<SS);
                delay_ms(2000);
                
                PORTB&=~(1<<SS);
                SPI_MasterTransmit(0x70);
                SPI_MasterTransmit(0x00);
               PORTB|=(1<<SS);
                delay_ms(2000);
                
                 PORTB&=~(1<<SS);
                SPI_MasterTransmit(0x80);
                SPI_MasterTransmit(0x00);
                 PORTB|=(1<<SS);
                 delay_ms(2000);
                
                 PORTB&=~(1<<SS);
                SPI_MasterTransmit(0xC0);
                SPI_MasterTransmit(0x00);
                 PORTB|=(1<<SS);
                 delay_ms(2000);
                
                 PORTB&=~(1<<SS);
                SPI_MasterTransmit(0xFF);
                SPI_MasterTransmit(0xFF);
                //SPI_MasterTransmit(0x80);
                //SPI_MasterTransmit(0x00);
                PORTB|=(1<<SS);				/*锁存数据*/
	        delay_ms(2000);
		
    }
}