10.3. Reset By Software
Software sequence for generating Power-on-reset
1) Power ON
2) Wait longer than 40 ms *1
3) Dummy reading *2
4) Readout VLF bit-1
5) Write 00h Address: Reg=32h *3 INIEN = 0b
6) Write 80h Address: Reg=3Fh TEST = 1
7) Write 6Ch Address: Reg=D0h
8) Write 03h Address: Reg=D1h
9) Write 10h Address: Reg=D2h
10) Write 20h Address: Reg=D3h
11) Wait more than 2 ms. released automatically *4
*1 When 40ms waiting time is so long time in your system, an another method.
Jump to step3 from step1.
At step4, when VLF is 1, write 0 to VLF. While VLF is 1, repeat reset to VLF and verify VLF is 0.
If VLF is cleared to 0, jump to step5. In this method, it have possibility this sequence is short than 40 ms.
After 40 ms, when VLF doesn't reset to 0, go to step5.
*2 Dummy reading. Any address is acceptable. In I
2
C communication, ignore ACK / NACK signal from RX8111CE.
*3 Should be execute this command even if VLF is 0. Even if VLF is 1, it available after step5.
*4 2ms is time for RESET processing.
Note: Except using this RESET sequence, don't access to D0h from D3h, and never write 1 to a TEST- bit.
11. Reference information
11.1. Reference Data
[ Finding the frequency stability ]
1. Frequency and temperature characteristics can be
approximated using the following equations.
fT = ( T − X )
2
fT : Frequency deviation in any temperature
[ 1 / C
2
] : Coefficient of secondary temperature
( −0.035 0.005 ) 10
−6
/ C
2
T [ C ] : Ultimate temperature ( +25 5 C )
X [ C ] : Any temperature
2. To determine overall clock accuracy, add the
frequency precision and voltage characteristics.
f/f = f/fo + fT + fV
f/f : Clock accuracy (stable frequency)
in any temperature and voltage.
f/fo : Frequency tolerance
fT : Frequency deviation in any temperature.
fV : Frequency deviation in any voltage.
3. How to find the date difference
Date Difference = f/f 86400 seconds.
For example: f/f = 11.574 10
-6
is an error of
approximately 1 second/day.
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