DS1511_CONTROL_A
rtc_read(DS1511_CONTROL_A); /* clear interrupts */
if (rtc_read(DS1511_CONTROL_A) & DS1511_IRQF) {
rtc_write(0, DS1511_CONTROL_A);
if (rtc_read(DS1511_CONTROL_A) & DS1511_BLF1)
rtc_read(DS1511_CONTROL_A);