atmega88_example.c

/*
	atmega88_example.c

 */

#ifndef F_CPU
#define F_CPU 8000000
#endif
#include <avr/io.h>
#include <stdio.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>
#include <avr/sleep.h>

/*
 * This demonstrate how to use the avr_mcu_section.h file
 * The macro adds a section to the ELF file with useful
 * information for the simulator
 */
#include "avr_mcu_section.h"
AVR_MCU(F_CPU, "atmega88");

/*
 * This small section tells simavr to generate a VCD trace dump with changes to these
 * registers.
 * Opening it with gtkwave will show you the data being pumped out into the data register
 * UDR0, and the UDRE0 bit being set, then cleared
 */
const struct avr_mmcu_vcd_trace_t _mytrace[]  _MMCU_ = {
	{ AVR_MCU_VCD_SYMBOL("UDR0"), .what = (void*)&UDR0, },	
	{ AVR_MCU_VCD_SYMBOL("UDRE0"), .mask = (1 << UDRE0), .what = (void*)&UCSR0A, },	
};


/* declare this in a .eeprom ELF section */
uint32_t value EEMEM = 0xdeadbeef;

static int uart_putchar(char c, FILE *stream) {
	if (c == '\n')
		uart_putchar('\r', stream);
	loop_until_bit_is_set(UCSR0A, UDRE0);
	UDR0 = c;
	return 0;
}

static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL,
                                         _FDEV_SETUP_WRITE);


int main()
{
	stdout = &mystdout;

	// read the eeprom value
	uint32_t c = eeprom_read_dword((void*)&value);
	printf("Read from eeprom 0x%08lx -- should be 0xdeadbeef\n", c);
	// change the eeprom
	eeprom_write_dword((void*)&value, 0xcafef00d);
	// re-read it
	c = eeprom_read_dword((void*)&value);
	printf("Read from eeprom 0x%08lx -- should be 0xcafef00d\n", c);

	// this quits the simulator, since interupts are off
	// this is a "feature" that allows running tests cases and exit
	sleep_cpu();
}