V3021SO8A EMMICRO [EM Microelectronic - MARIN SA], V3021SO8A Datasheet - Page 11

• Manufacturer Part Number: V3021SO8A
• Description: Ultra Low Power 1-Bit 32 kHz RTC
• Manufacturer: EMMICRO [EM Microelectronic - MARIN SA]

Reading the Current Time and Date
Clock and Calendar
The Time and date addresses in the RAM (see Table 6)
provide access to the seconds, minutes, hours, day of
month, month, year, week day, and week number. These
parameters have the ranges indicated on Table 6 and are
in BCD format. If a parameter is found to be out of range,
it will be cleared on its being next incremented.
V3021 incorporates leap year correction and week
number calculation. The week number changes only at
the incrementation of the day number from 7 to 1. If week
52 day 7 falls on the 25
the week number will change to 0, otherwise it will be
week 1.
Monday as 1.
Reading of the current time and date must be preceded
by a Copy_clock_to_RAM command. The time and date
status bits will indicate which time and date addresses
changed since the last time the command was used (see
Fig.
Copy_clock_to_RAM command is held unchanged in the
RAM, except when power (V
change the current time and date in the clock, the desired
time an date must first be written to the RAM, the time set
lock bit cleared, and then a Copy_RAM_to_clock
command sent (see Fig. 10). The time set lock bit can be
used to prevent unauthorized setting of the clock.
Copyright © 2005, EM Microelectronic-Marin SA
9).
Similar for hours, day of month, week
day, month, year and week number
Week days are numbered from 1 to 7 with
Read time and data status bits,
Is the seconds status bit set,
Is the minutes status bit set,
Send copy_clock_to_RAM
R
The
Read seconds, addr. 2
Read minutes, addr. 3
Current time and date
addr. 1, bit 0
addr. 1, bit 1
addr. F hex
time
addr. 1
th
, 26
Yes
Yes
and
th
DD
or 27
) has failed totally.
date
th
of December, then
No
No
from
the
Fig. 9
The
last
To
Setting the Current Time and Date
Frequency Measurement
Setting bit 0 at address 0 will put a pulsed current source
(25 µA) onto the I/O pin, when the device is not chip
selected (ie. CS input high). The current source will be
pulsed on/off at 256 Hz. The period for ± 0 ppm time
keeping is 3.90625 ms. To measure the frequency signal
on pin I/O, the data bus must be high impedance. The
best way to ensure this is to hold the microprocessor and
peripherals in reset mode while measuring the frequency.
The clarity of the signal measured at pin I/O will depend
on both the probe input impedance (typically 1 M Ω ) and
the magnitude of the leakage current from other devices
driving the line connected to pin I/O.
measured is unclear, put a 200 k Ω resistor from pin I/O to
V
source (25 µA) is not sufficient to drive the data bus line in
case of any other device driving the line, but it is sufficient
to take the line to a high logic level when the data bus is in
high impedance.
Use a crystal of nominal C
section "Operating Conditions".
Microcrystal is recommended. The accuracy of the time
keeping is dependent upon the frequency tolerance and
the load capacitance of the crystal.
corresponds to one second a day.
Test
From the various test features added to the V3021 some
may be activated by the user. Table 7a shows the test
mode b its. Table 8 shows the 3 available test modes and
how they can be activated. Test mode 0 is activated by
setting bit 2, address 0, and causes all time keeping to be
accelerated by 32. Test mode 1 is activated by setting bit
3, address 0, and causes all the time and date locations,
address 2 to address9, to be incremented in parallel at 1
Hz with no carry over (independent of each other). The
third test mode combines the previous two resulting in
parallel incrementing at 32 Hz.
11
SS
. It should be noted that the magnitude of the current
Send copy_RAM_to_clock command,
of month, week day, month, year and
Set the time set lock bit, addr. 0, bit 4
Write seconds, minutes, hours, day
Clear the time set lock bit,
week number to the RAM
addr. 0, bit 4
addr. E hex
L
= 8.2 pF as specified in the
www.emmicroelectronic.com
The MX series from
V3021
If the signal
11.57 ppm
Fig. 10