Đây là code của mình, SRF05/mode1/Atmega128.
#define F_CPU 14745600UL
#define STOP_CLK 0x08 // Stop clock
#define START_CLK 0x0A // Start clock with 1:8 prescaler CTC mode
#define START_CLK_N 0x02 // Start clock running 1:8 prescaler in normal mode
#include <avr/io.h>
#include <string.h>
#include <stdio.h>
#include <util/delay.h>
#include <stdint.h>
#include "knihovnaLCD.c"
float s;
char buffer [50];
void setup(void)
{
DDRA = 0x00; // Port A asIN
DDRC = 0xFF; // Port C as OUT
TCCR1A = 0x00; // Set timer up in CTC mode
TCCR1B = 0x08;
TWBR = 0x20; // 100MHz I2C clock frequency
}
void waitForTimer(void)
{
while(!(TIFR&0x10)); // wait for timer to set compare match flag
TCCR1B = STOP_CLK; // Stop the timer
}
void startTimer(unsigned int time)
{
OCR1A = time; // Time set to count to
TIFR = 0x10; // Clear timer campare match flag
TCNT1 = 0x00; // Clear timer to zero
TCCR1B = START_CLK; // Start timer running 1:8 prescaler
}
unsigned int getEcho(void)
{
unsigned int range;
TCNT1 = 0x00; // Clear timer to zero
TCCR1B = START_CLK_N;
while(bit_is_clear(PINA,0) && TCNT1 < 0xC350) // Wait for echo pin to go high, this indicates the start of the incoming pulse
{
}
if (TCNT1 > 0xC300) //Time over
{
TCCR1B = STOP_CLK;
return(999);
}
TCCR1B = STOP_CLK;
TCNT1 = 0x00; // Clear timer to zero
TCCR1B = START_CLK_N; // Start timer running 1:8 prescaler in normal mode
while(bit_is_set(PINA,0)); // Echo pin goes high
{ // Just wait
}
TCCR1B = STOP_CLK; // Echo pin has just fallen down. Stop the timer
range = TCNT1/107; // Read back value in the timer counter register
return(range);
}
int main(void)
{
setup();
startTimer(0xFFFF);
waitForTimer();
LCD_Init();
LCD_Clear();
while (1)
{
PORTC=255;
_delay_us(10);
PORTC=0;
s = getEcho();
sprintf (buffer, "s =%u ", (int)s);
LCD_Position(1 , 1);
LCD_WriteString(buffer);
_delay_ms(100);
};
}