 	 * 3. Rows
 	 * 4. Flip frame, if available, otherwise; repeat.
 	 */
+	sei();
 	pwm_i++;
 	if (pwm_i >= ARRAY_SIZE(pwm_lengths)) {
 		pwm_i = 0;

uint8_t row_i = 0;
volatile uint8_t may_flip = 0;
int pwm_lengths[] = { 0x30, 0x10, 0x06 }; // PWM cycle lengths
int pwm_i = 0; // Current PWM cycle

// Hardware configuration
uint8_t pin_col[] = {5, A0, 4, A1, 3, A2, 2, A3};
#define PIN_ROW_LATCH 6
#define PIN_COL_LATCH 8

// Serial access


ISR(TIMER1_COMPA_vect)
{
	// Force screen off if not yet happened (force OC1A on)
	TCCR1A = (1 << COM1A1);
	TCCR1C = (1 << FOC1A);
  
	// Load new data to LED driver
	digitalWrite(PIN_COL_LATCH, HIGH);
	
	// Are we moving to next segment?
	if (pwm_i == 0) {
		// Switch the row on row driver if needed
		if (col_i == 0) {
			SPI.transfer(1 << row_i);
