HT66F0172 Datasheet, PDF (28/115 Pages) Holtek Semiconductor Inc – Enhanced A/D Flash 8-Bit MCU

HT66F0172/HT66F0174
Enhanced A/D Flash 8-Bit MCU
EEPROM Data Memory (only for HT66F0174)
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. Unlike the Program Memory and RAM Data
Memory, the EEPROM Data Memory is not directly mapped into memory space and is therefore
not directly accessible in the same way as the other types of memory. Instead it has to be accessed
indirectly through the EEPROM control registers.
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 Bank1, 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 register,
BP, set to the value, 01H, before any operations on the EEC register are executed.
EEPROM Control Registers List
Name
7
6
5
EEA
—
—
D5
EED
D7
D6
D5
EEC
—
—
—
Bit
4
3
2
1
0
D4
D3
D2
D1
D0
D4
D3
D2
D1
D0
—
WREN
WR
RDEN
RD
EEA Register
Bit
7
Name
—
R/W
—
POR
—
6
5
4
3
2
1
0
—
D5
D4
D3
D2
D1
D0
—
R/W
R/W
R/W
R/W
R/W
R/W
—
0
0
0
0
0
0
Bit 7 ~ 6
Bit 5 ~ 0
Unimplemented, read as "0"
D5~D0: Data EEPROM address
Data EEPROM address bit 5 ~ bit 0
Rev. 1.00
28
July 11, 2013