Rev. 1.71
32
April 11, 2017
Rev. 1.71
33
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
STATUS Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
TO
OV
Z
AC
C
R/W
—
—
R
R
R/W
R/W
R/W
R/W
POR
—
—
0
0
×
×
×
×
"×" unknown
B
it 7~6
Unimplemented, read as "0"
B
it 5
TO
: Watchdog Time-Out flag
0: After power up or executing the "CLR WDT" or "HALT" instruction
1: A watchdog time-out occurred.
B
it 4
: Power down flag
0: After power up or executing the "CLR WDT" instruction
1: By executing the "HALT" instruction
B
it 3
OV
: Overflow flag
0: no overflow
1: an operation results in a carry into the highest-order bit but not a carry out of the highest-
order bit or vice versa.
B
it 2
Z
: Zero flag
0: The result of an arithmetic or logical operation is not zero
1: The result of an arithmetic or logical operation is zero
B
it 1
AC
: Auxiliary flag
0: no auxiliary carry
1: an operation results in a carry out of the low nibbles in addition, or no borrow from the high
nibble into the low nibble in subtraction
B
it 0
C
: Carry flag
0: no carry-out
1: an operation results in a carry during an addition operation or if a borrow does not take place
during a subtraction operation
C
is also affected by a rotate through carry instruction.
EEPROM Data Memory
These 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 32×8 bits for this series of devices. 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 two address registers and
one data register in Bank 0 and a single control register in Bank 1.