mega8init.c

一个简单的MEGA8初始化程序

//ICC-AVR application builder : 2009-5-14 上午 10:50:52
// Target : M8
// Crystal: 11.0592Mhz

#include <iom8v.h>
#include <macros.h>

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

//TIMER0 initialize - prescale:1024
// desired value: 10mSec
// actual value: 10.000mSec (0.0%)
void timer0_init(void)
{
 TCCR0 = 0x00; //stop
 TCNT0 = 0x94; //set count
 TCCR0 = 0x05; //start timer
}

#pragma interrupt_handler timer0_ovf_isr:10
void timer0_ovf_isr(void)
{
 TCNT0 = 0x94; //reload counter value
}

//SPI initialize
// clock rate: 5529600hz
void spi_init(void)
{
 SPCR = 0xDC; //setup SPI
 SPSR = 0x01; //setup SPI
}

#pragma interrupt_handler spi_stc_isr:11
void spi_stc_isr(void)
{
 //byte in SPDR has been sent/received
}

//UART0 initialize
// desired baud rate: 9600
// actual: baud rate:9600 (0.0%)
// char size: 8 bit
// parity: Disabled
void uart0_init(void)
{
 UCSRB = 0x00; //disable while setting baud rate
 UCSRA = 0x00;
 UCSRC = BIT(URSEL) | 0x06;
 UBRRL = 0x47; //set baud rate lo
 UBRRH = 0x00; //set baud rate hi
 UCSRB = 0xD8;
}

#pragma interrupt_handler uart0_rx_isr:12
void uart0_rx_isr(void)
{
 //uart has received a character in UDR
}

#pragma interrupt_handler uart0_tx_isr:14
void uart0_tx_isr(void)
{
 //character has been transmitted
}

#pragma interrupt_handler int0_isr:2
void int0_isr(void)
{
 //external interupt on INT0
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 timer0_init();
 spi_init();
 uart0_init();

 MCUCR = 0x03;
 GICR  = 0x40;
 TIMSK = 0x01; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void main( void )
{
 init_devices();
 while(1);
}