SPI multi-machine loop communication based on AVR microcontroller

SPI communication with one master and three slaves

The program is as follows: host://ICC-AVR application builder: 2012-1-13 18:56:57

// Target : M16

// Crystal: 8.0000Mhz

// Complete program download: http://www.51hei.com/f/djhltl.rar 

#include 

#include 


#define Load_High PORTB|=(1<<4)

#define Load_Low PORTB&=~(1<<4)

unsigned char tab[]={0x00,0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80}; //Flowing light array

/*------------------------------------------------ ------------------

Function name: void SPImasterInit(void)

Function: SPI initializes as a master

parameter:

Return value: None

                     SPI Control Register Introduction

SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0

SPIE: Interrupt Enable  

SPE: SPI Enable

DORD: Data order 1 is LSB first, 0 is MSB first

MSTR: Master-slave selection 1 is master, 0 is slave. When MSTR is set, the host mode is selected, otherwise it is a slave. If MSTR is "1",

      If SS is configured as an input and is pulled low, MSTR is cleared and SPIF in register SPSR is set. The user must re-

 Set MSTR to enter master mode.

CPOL: Clock polarity see ATMEGA16L (Chinese) P130

CPHA: Clock Phase

SPR1, SPR0: SPI clock rate selection 1 and 0 SPR1 and SPR0 have no effect on the slave.

-------------------------------------------------- ---------------*/

void SPImasterInit(void) //SPI initialization

{

  DDRB|=(1<<7)|(1<<5)|(1<<4); //Set SCK, MOSI as output and others as input

  SPCR|=(1<8)

    {

     i=0;

    }

         Transmit(tab[i]); //Send data

PORTC=SPDR; //The host receives the data from the slave and generates an action

delay(100);

  }

 

}
Slave: #include
#include 
//#include
#define uchar unsigned char
#define uint unsigned int

void delay(uint ms)
{
        uint i,j;
for(i=0;i