int main()
{
TCCR0A = 0; // configure timer0 to run at 78 kHz
TCCR0B = 0x04; // and overflow when TCNT0 = 256 (~3 ms)
play_from_program_space(rhapsody);
while(1)
{
// allow the sequence to keep playing automatically through the following delays
#ifndef ALWAYS_CHECK
play_mode(PLAY_AUTOMATIC);
#else
play_mode(PLAY_CHECK);
#endif
lcd_goto_xy(0, 0);
print("blink!");
int i;
for (i = 0; i < 8; i++)
{
#ifdef ALWAYS_CHECK
play_check();
#endif
red_led(1);
delay_ms(500);
red_led(0);
delay_ms(500);
}
lcd_goto_xy(0, 0);
print("timing");
lcd_goto_xy(0, 1);
print(" "); // clear bottom LCD line
// turn off automatic playing so that our time-critical code won't be interrupted by
// the buzzer's long timer1 interrupt. Otherwise, this interrupt could throw off our
// timing measurements. Instead, we will now use playCheck() to keep the sequence
// playing in a way that won't throw off our measurements.
#ifndef ALWAYS_AUTOMATIC
play_mode(PLAY_CHECK);
#endif
unsigned char maxTime = 0;
for (i = 0; i < 8000; i++)
{
TCNT0 = 0;
while (TCNT0 < 20) // time for ~250 us
;
if (TCNT0 > maxTime)
maxTime = TCNT0; // if the elapsed time is greater than the previous max, save it
#ifndef ALWAYS_AUTOMATIC
play_check(); // check if it's time to play the next note and play it if so
#endif
}
lcd_goto_xy(0, 1);
print("max=");
print_long((unsigned int)maxTime);
print(" "); // overwrite any left over characters
}
}
// Waits for the next byte and returns it. Runs play_check to keep
// the music playing and calls pid_check() to keep following the line.
char read_next_byte()
{
while(serial_get_received_bytes() == read_index)
{
play_check();
// pid_check takes some time; only run it if we don't have more bytes to process
if(serial_get_received_bytes() == read_index)
pid_check();
}
char ret = buffer[read_index];
read_index ++;
if(read_index >= 100)
read_index = 0;
return ret;
}
