Rev. 1.00
36
September 11, 2018
Rev. 1.00
37
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
•
PDF is cleared by a system power-up or executing the "CLR WDT" instruction. PDF is set by
executing the "HALT" instruction.
•
TO is cleared by a system power-up or executing the "CLR WDT" or "HALT" instruction. TO is
set by a WDT time-out.
•
CZ is the operational result of different flags for different instructions. Refer to register
definitions for more details.
•
SC is the result of the "XOR" operation which is performed by the OV flag and the MSB of the
current instruction operation result.
In addition, on entering an interrupt sequence or executing a subroutine call, the status register will
not be pushed onto the stack automatically. If the contents of the status registers are important and if
the subroutine can corrupt the status register, precautions must be taken to correctly save it.
• STATUS Register
Bit
7
6
5
4
3
2
1
0
Name
SC
CZ
TO
OV
Z
AC
C
R/W
R/W
R/W
R
R
R/W
R/W
R/W
R/W
POR
x
x
0
0
x
x
x
x
"x": unknown
Bit 7
SC
: The result of the "XOR" operation which is performed by the OV flag and the
MSB of the instruction operation result.
Bit 6
CZ
: The the operational result of different flags for different instuctions.
For SUB/SUBM/LSUB/LSUBM instructions, the CZ flag is equal to the Z flag.
For SBC/SBCM/LSBC/LSBCM instructions, the CZ flag is the "AND" operation
result which is performed by the previous operation CZ flag and current operation zero
flag.
For other instructions, the CZ flag willl not be affected.
Bit 5
TO
: Watchdog Time-Out flag
0: After power up or executing the "CLR WDT" or "HALT" instruction
1: A watchdog time-out occurred.
Bit 4
: Power down flag
0: After power up or executing the "CLR WDT" instruction
1: By executing the "HALT" instruction
Bit 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.
Bit 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
Bit 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
Bit 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
The C flag is also affected by a rotate through carry instruction.