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RTC - 9701 JE
12. Read / Write data
12.1. Serial data transfer method
This is a serial data transfer method in 4 lines form (or 3 lines form). Mode, address and data are transferred in MSB-first
in respective order.
The first 4 bits (called mode field) determines the mode and the data size of the other fields (address and data fields).
12.1.1. Mode field
l
The first 4 bits determines the mode.
Mode field
Data bit
* Make sure m2 is set to "0".
12.1.2. Address field and data field
l
RTC mode (m1 bit =0)
Mode field
Address field
Data field
l
EEPROM Memory mode (m1 bit =1)
Mode field
Address field
Data field
*
Since segment bits (seg3 to seg1) are used for memory expansion, write "0" to them.
m3
Read/Write
0
0 : write
1
1 : read
m3
m2
m1
a3
a2
a1
d7
d6
d5
m3
m2
m1
seg3
seg2
seg1
a6
a5
a4
dF
dE
dD
d7
d6
d5
m2
Reserved
0 *
0
*
m0
a0
d4
d3
m0
a7
a3
a2
dC
dB
d4
d3
Page-14
m1
m0
BANK register
00: RTC mode
01: Reserved
10: EEPROM Memory
11: Reserved
d2
d1
d0
a1
a0
0
dA
d9
d8
d2
d1
d0
MQ - 362 - 03
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