Rev. 1.20
40
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Rev. 1.20
41
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BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
EEPROM Data Memory
T
he devices contain an area of internal EEPROM Data Memory. EEPROM, which stands for
Electrically Erasable Programmable Read Only Memory, is by its nature a non-volatile form of
memory, with data retention even when its power supply is removed. By incorporating this kind
of data memory, a whole new host of application possibilities are made available to the designer.
The availability of EEPROM storage allows information such as product identification numbers,
calibration values, specific user data, system setup data or other product information to be stored
directly within the product microcontroller. The process of reading and writing data to the EEPROM
memory has been reduced to a very trivial affair.
EEPROM Data Memory Structure
The EEPROM Data Memory capacity is 64×8 bits. Unlike the Program Memory and RAM Data
Memory, the EEPROM Data Memory is not directly mapped and is therefore not directly accessible
in the same way as the other types of memory. Read and Write operations to the EEPROM are
carried out in single byte operations using an address and data register in Sector 0 and a single
control register in Sector 1.
Device
Capacity
Address
BS82B12A-�
64×8
00H~�FH
BS82C16A-�
BS82D20A-�
EEPROM Registers
Three registers control the overall operation of the internal EEPROM Data Memory. These are the
address register, EEA, the data register, EED and a single control register, EEC. As both the EEA
and EED registers are located in Bank 0, they can be directly accessed in the same way as any other
Special Function Register. The EEC register however, being located in Bank 1, cannot be directly
addressed directly and can only be read from or written to indirectly using the MP1 Memory Pointer
and Indirect Addressing Register, IAR1. Because the EEC control register is located at address 40H
in Bank 1, the MP1 Memory Pointer must first be set to the value 40H and the Bank Pointer, BP, set
to the value, 01H, before any operations on the EEC register are executed.
EEPROM Control Registers List
Name
Bit
7
6
5
4
3
2
1
0
EEA
—
—
D�
D4
D�
D2
D1
D0
EED
D7
D6
D�
D4
D�
D2
D1
D0
EEC
—
—
—
—
WREN
WR
RDEN
RD
EEA Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
D�
D4
D�
D2
D1
D0
R/W
—
—
R/W
R/W
R/W
R/W
R/W
R/W
POR
—
—
0
0
0
0
0
0
Bit 7 ~ 6
Unimplemented, read as "0"
Bit 5 ~ 0
Data EEPROM address
Data EEPROM address bit 5 ~ bit 0
