Micro Crystal
Ultra Small Real-Time Clock Module with SPI-Bus Interface
RV-8063-C7
October 2018
13/58
Rev. 1.1
02h
– Offset Register
This register holds the OFFSET value to digitally compensate the initial frequency deviation of the 32.768 kHz
oscillator or for aging adjustment (see FREQUENCY OFFSET COMPENSATION).
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
02h
Offset
MODE
OFFSET
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
MODE
Offset Mode
0
Normal Mode: Offset is made once every two hours.
1
Fast Mode: Offset is made every 4 minutes.
6:0
OFFSET
-64 to
+63
Offset value.
For MODE = 0, each LSB introduces an offset of 4.34 ppm. For MODE = 1,
each LSB introduces an offset of 4.069 ppm. The values of 4.34 ppm and
4.069 ppm are based on a nominal 32.768 kHz clock. The offset value is
coded in two’s complement giving a range of +63 LSB to -64 LSB (see
FREQUENCY OFFSET COMPENSATION).
OFFSET
OFFSET compensation value
in decimal
Compensation pulses
in steps
CLKOUT frequency
offset in ppm
(1)
Normal Mode
MODE = 0
Fast Mode
MODE = 1
0111111
63
+63
+273.420
+256.347
0111110
62
+62
+269.080
+252.278
:
:
:
:
:
0000001
1
+1
+4.340
+4.069
0000000
0
0
0
0
1111111
127
-1
-4.340
-4.069
1111110
126
-2
-8.680
-8.138
:
:
:
:
:
1000001
65
-63
-273.420
-256.347
1000000
64
-64
-277.760
-260.416
(1)
The frequency offset measured at CLKOUT pin can be compensated by computing the compensation value OFFSET and writing it into
the Offset register (see OFFSET COMPENSATION CALCULATION WORKFLOW).
03h - RAM
Free RAM byte, which can be used for any purpose, for example, status byte of the system.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
03h
RAM
RAM data
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7:0
RAM
00h to
FFh
User RAM
