调试通过的AVR mega16 SPI双机通讯例子 （为新手设计，简单易懂）本程序实现的功能：主机发送1~255，丛机接收并在LED上显示出来。连接方式： 两个mega16最小系统板 PB4到PB7全部对连。
本程序在本站的最小系统板上测试通过，我向你担保本程序的正确性。
//ICC-AVR application builder : 2007-7-18 13:01:11
// Target : M16
// Crystal: 7.3728Mhz
// 作者：古欣
// AVR与虚拟仪器 [url]http://www.avrvi.com[/url]
// 功能：SPI主机模式，循环发送从1~255
#include <iom16v.h>
#include <macros.h>
void port_init(void)
{
PORTA = 0x00;
DDRA = 0x00;
PORTB = 0x00;
DDRB = 0x00;
PORTC = 0x00; //m103 output only
DDRC = 0x00;
PORTD = 0x00;
DDRD = 0x00;
}
//SPI initialize
// clock rate: 57599hz
void spi_init(void)
{
PORTB |= (1<<PB4) | (1<<PB5) | (1<<PB6) | (1<<PB7);
DDRB |= (1<<DDB5) | (1<<DDB7) | (1<<DDB4); //Set MOSI, SCK AND SS as outputs
SPCR = 0x73; //setup SPI
SPSR = 0x00; //setup SPI
}
//call this routine to initialize all peripherals
void init_devices(void)
{
//stop errant interrupts until set up
CLI(); //disable all interrupts
port_init();
spi_init();
MCUCR = 0x00;
GICR = 0x00;
TIMSK = 0x00; //timer interrupt sources
SEI(); //re-enable interrupts
//all peripherals are now initialized
}
void SPI_MasterTransmit(char cData)
{
PORTB &=~ (1<<PB4); //强制接收方进入从模式
SPCR |= (1<<MSTR); // MSTR有时会被清零，这里强制进入主机模式
/* 启动数据传输 */
SPDR = cData;
/* 等待传输结束 */
while(!(SPSR & (1<<SPIF)))
;
PORTB |= (1<<PB4);
}
void Delay(void) //延时，没有详细计算
{
unsigned int i,j;
for(i=1000;i>0;i--)
{
for(j=200;j>0;j--)
;
}
}
void main(void)
{
unsigned char i=0;
init_devices();
while(1)
{
for(i=255;i>0;i--)
{
SPI_MasterTransmit(i);
Delay();
}
}
}
//ICC-AVR application builder : 2007-7-18 12:56:10
// Target : M16
// Crystal: 7.3728Mhz
// 作者：古欣
// AVR与虚拟仪器 [url]http://www.avrvi.com[/url]
// 功能：从机模式，中断方式接收，并在LED上显示
#include <iom16v.h>
#include <macros.h>
void port_init(void)
{
PORTA = 0x00;
DDRA = 0xFF;
PORTB = 0x00;
DDRB = 0x00;
PORTC = 0x00; //m103 output only
DDRC = 0x00;
PORTD = 0x00;
DDRD = 0x00;
}
//SPI initialize
// clock rate: 57599hz
void spi_init(void)
{
SPCR = 0xE3; //setup SPI
SPSR = 0x00; //setup SPI
}
#pragma interrupt_handler spi_stc_isr:11
void spi_stc_isr(void)
{
//byte in SPDR has been sent/received
PORTA = SPDR;
}
//call this routine to initialize all peripherals
void init_devices(void)
{
//stop errant interrupts until set up
CLI(); //disable all interrupts
port_init();
spi_init();
MCUCR = 0x00;
GICR = 0x00;
TIMSK = 0x00; //timer interrupt sources
SEI(); //re-enable interrupts
//all peripherals are now initialized
}
void main(void)
{
init_devices();
DDRB|=(1<<PB6); //MOSI 设置为输出
while(1)
;//等待中断
}
