Field Name Bits Default Description
Rate Selection(RS1) 1 0b
Rate Selection(RS2) 2 0b
Rate Selection(RS3) 3 0b
15-stage frequency divider or disable the divider output (flat
output signal). The tap selected can be used to generate a
periodic interrupt. See the following table for frequency
selection.
Bank Selection(DV0) 4 0b DV0 = 0 selects Bank 0; DV0 = 1 selects Bank 1. The SB600,
it has an alternate way to access the RAM without the use of
bank select bit. Port 72/73 can be used as the index to access
the full 256 bytes of RAM directly.
Reserved 6:5
Update In Progress(UIP) 7 0b If SET bit = 1, UIP is cleared.
If UIP = 1, the update transfer will soon occur.
If UIP = 0, the update transfer will not occur for at least 244us.
[Read-only]
Register A: Control register
Rate Selection Bits RS3 RS2 RS1 RS0 Tap Frequency(Interrupt Rate)
0 0 0 0 Flat Signal(None)
0 0 0 1 256 Hz (3.90625 ms)
0 0 1 0 128 Hz (7.8125 ms)
0 0 1 1 8.192 kHz (122.070 us)
0 1 0 0 4.096 kHz (244.141 us)
0 1 0 1 2.048 kHz (488.281 us)
0 1 1 0 1.024 kHz (976.5625 us)
0 1 1 1 512 Hz (1.953125 ms)
1 0 0 0 256 Hz (3.90625 ms)
1 0 0 1 128 Hz (7.8125 ms)
1 0 1 0 64 Hz (15.625 ms)
1 0 1 1 32 Hz (31.25 ms)
1 1 0 0 16 Hz (62.5 ms)
1 1 0 1 8 Hz (125 ms)
1 1 1 0 4 Hz (250 ms)
1 1 1 1 2 Hz (500 ms)
Register B - RW – 8 bits - [RTC_Reg: 0Bh] Field Name Bits Default Description
Reserved 0 0b
HourMode 1 0b Hour mo de; 0 = 12 hour mode; 1 = 24 hour mode
Reserved 3:2 00
Update Ended Interrupt Enable(UIE) 4 0b UIE enables the Update End Flag (UF) bit in
Register C to assert IRQ. If SET bit = 1, UIE is
cleared.
Alarm Interrupt Enable (AIE) 5 0b AIE enables the Alarm Flag (AF) bit in Register C to
assert IRQ.
Periodic Interrupt Enable (PIE) 6 0b PIE enables the Periodic Interrupt Flag (PF) bit in
Register C to assert IRQ.
Set new time (SET) 7 0b If SET bit = 1, no internal updating for Time
Registers is allowed.
If SET bit = 0, the Time Registers are updated every
second.
Register B: Control register
Register C - R – 8 bits - [RTC_Reg: 0Ch] Field Name Bits Default Description
Reserved 3:0 0h