-----------------Translated from Chinese article: Article Number 99549. Content can be found on pg 6 of the datasheet.-----------------
DS1554 constantly monitors the voltage of the internal battery. The state of lithium battery can be obtained by reading the B4 (BLF bit) of the Flags register (7FFF0h). BLF = 0 indicates that the battery can provide sufficient energy. Once the BLF bit shows "1," it means that the battery is exhausted.