Rainbow Electronics DS1286 - Manual (Page 3)

DS1286
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WATCHDOG TIMEKEEPER REGISTERS
The Watchdog Timekeeper has 64 registers which are 8 bits wide that contain all of the Timekeeping,
Alarm, Watchdog, Control, and Data information. The Clock, Calendar, Alarm, and Watchdog registers
are memory locations which contain external (user-accessible) and internal copies of the data. The
external copies are independent of internal functions except that they are updated periodically by the
simultaneous transfer of the incremented internal copy (see Figure 1). The Command Register bits are
affected by both internal and external functions. This register will be discussed later. The 50 bytes of
RAM registers can only be accessed from the external address and data bus. Registers 0, 1, 2, 4, 6, 8, 9,
and A contain time of day and date information (see Figure 2). Time of Day information is stored in
BCD. Registers 3, 5, and 7 contain the Time of Day Alarm information. Time of Day Alarm information
is stored in BCD. Register B is the Command Register and information in this register is binary. Registers
C and D are the Watchdog Alarm registers and information which is stored in these two registers is in
BCD. Registers E through 3F are user bytes and can be used to contain data at the user’s discretion.