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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
EEPROM Data Memory
One of the special features in the device is its 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 for the device. Unlike the Program Memory
and RAM Data Memory, the EEPROM Data Memory is not directly mapped into memory space
and is therefore not directly addressable 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.
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 all sectors, they can be directly accessed in the same was as any
other Special Function Register. The EEC register however, being located in Sector 1, cannot be
directly addressed directly and can only be read from or written to indirectly using the MP1L/MP1H
or MP2L/MP2H Memory Pointer and Indirect Addressing Register, IAR1 or IAR2. Because the
EEC control register is located at address 40H in Sector 1, the MP1L or MP2L Memory Pointer low
byte must first be set to the value 40H and the MP1H or MP2H Memory Pointer high byte set to the
value 01H before any operations on the EEC register are executed.
Register
Name
Bit
7
6
5
4
3
2
1
0
EEA
—
—
D5
D4
D3
D2
D1
D�
EED
D�
D6
D5
D4
D3
D2
D1
D�
EEC
—
—
—
—
WRE�
WR
RDE�
RD
EEPROM Control Registers List
EEA Register
Bit
7
6
5
4
3
2
1
0
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—
—
D5
D4
D3
D2
D1
D�
R/W
—
—
R/W
R/W
R/W
R/W
R/W
R/W
POR
—
—
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Bit 7~6
Unimplemented, read as “0”
Bit 5~0
D5~D0
: Data EEPROM address
Data EEPROM address bit 5 ~ bit 0