Rev. B | Page 31 of 36
Table 119. SLP_CNT (Page 3, Base Address = 0x10)
Normal sleep mode
Programmable time bits; 1 sec/LSB;
0x00 = indefinite
If the sleep mode and power-down mode bits are both set high,
the normal sleep mode (SLP_CNT) bit takes precedence.
The USER_SCR_x registers (see Table 120, Table 121, Table 122,
and Table 123) provide four 16-bit registers for storing data.
Table 120. USER_SCR_1 (Page 2, Base Address = 0x74)
Table 121. USER_SCR_2 (Page 2, Base Address = 0x76)
Table 122. USER_SCR_3 (Page 2, Base Address = 0x78)
Table 123. USER_SCR_4 (Page 2, Base Address = 0x7A)
Real-Time Clock Configuration/Data
The VDDRTC power supply pin (see Table 5, Pin 23) provides
a separate supply for the real-time clock (RTC) function. This
enables the RTC to keep track of time, even when the main supply
(VDD) is off. Configure the RTC function by selecting one of
two modes in CONFIG (see Table 74). The real-time clock
data is available in the TIME_MS_OUT register (see Table 124),
TIME_DH_OUT register (see Table 125), and TIME_YM_OUT
register (see Table 126). When using the elapsed timer mode,
the time data registers start at 0x0000 when the device starts
up (or resets) and begin keeping time in a manner that is
similar to a stopwatch. When using the clock/calendar mode,
write the current time to the real-time registers in the following
sequence: seconds (TIME_MS_OUT[5:0]), minutes (TIME_
MS_OUT[13:8]), hours (TIME_DH_OUT[5:0]), day
(TIME_DH_OUT[12:8]), month (TIME_YM_OUT[3:0]),
and year (TIME_YM_OUT[14:8]). The updates to the timer
do not become active until a successful write to the TIME_
YM_OUT[14:8] byte. The real-time clock registers reflect the
newly updated values only after the next seconds tick of the
clock that follows the write to TIME_YM_OUT[14:8] (year).
Writing to TIME_ YM_OUT[14:8] activates all timing values;
therefore, always write to this location last when updating the
timer, even if the year information does not require updating.
Write the current time to each time data register after setting
CONFIG = 1 (DIN = 0x8003, DIN = 0x8A01). Note that
CONFIG provides a bit for managing daylight savings time.
After the CONFIG and TIME_xx_OUT registers are
configured, set GLOB_CMD = 1 (DIN = 0x8003, DIN =
0x8204, DIN = 0x8300) to back these settings up in flash, and
use a separate 3.3 V source to supply power to the VDDRTC
function. Note that access to time data in the TIME_xx_OUT
registers requires normal operation (VDD = 3.3 V and full
startup), but the timer function only requires that VDDRTC =
3.3 V when the rest of the ADIS16488 is turned off.
Table 124. TIME_MS_OUT (Page 0, Base Address = 0x78)
Minutes, binary data, range = 0 to 59
Seconds, binary data, range = 0 to 59
Table 125. TIME_DH_OUT (Page 0, Base Address = 0x7A)
Day, binary data, range = 1 to 31
Hours, binary data, range = 0 to 23
Table 126. TIME_YM_OUT (Page 0, Base Address = 0x7C)
Year, binary data, range = 0 to 99, relative to 2000 A.D.
Month, binary data, range = 1 to 12