DS1216 Datasheet, PDF (6/15 Pages) Dallas Semiconductor – SmartWatch RAM DS1216B/C/D/H SmartWatch ROM DS1216E/F

DS1216 SmartWatch RAM/SmartWatch ROM
SMARTWATCH REGISTER INFORMATION
The SmartWatch information is contained in eight registers of 8 bits, each of which is sequentially
accessed one bit at a time after the 64-bit pattern recognition sequence has been completed. When
updating the SmartWatch registers, each must be handled in groups of 8 bits. Writing and reading
individual bits within a register could produce erroneous results. These read/write registers are defined in
Figure 3.
Data contained in the SmartWatch registers is in binary-coded decimal (BCD) format. Reading and
writing the registers is always accomplished by stepping through all eight registers, starting with bit 0 of
register 0 and ending with bit 7 of register 7.
AM-PM/12-/24-MODE
Bit 7 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour
mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour
mode, bit 5 is the 20-hour bit (20 to 23 hours).
OSCILLATOR AND RESET BITS
Bits 4 and 5 of the day register are used to control the RST and oscillator functions. Bit 4 controls the
RST (pin 1). When the RST bit is set to logic 1, the RST input pin is ignored. When the RST bit is set to
logic 0, a low input on the RST pin will cause the SmartWatch to abort data transfer without changing
data in the watch registers. Bit 5 controls the oscillator. When set to logic 1, the oscillator is off. When set
to logic 0, the oscillator turns on and the watch becomes operational. These bits are shipped from the
factory set to logic 1.
ZERO BITS
Registers 1 to 6 contain one or more bits that always read logic 0. When writing these locations, a logic 1
or 0 is acceptable.
ADDITIONAL INFORMATION
Refer to Application Note 52: Using the Dallas Phantom Real-Time Clocks (available on our website at
www.maxim-ic.com/RTCapps) for information about using regarding optional modifications and the
phantom clock contained within the SmartWatch.
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