HT48R065G View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT48R065G' PDF : 126 Pages View PDF
HT48R064G/065G/066G/0662G
Enhanced I/O Type 8-Bit OTP MCU with OPA
Status Register - STATUS
This 8-bit register contains the zero flag (Z), carry flag (C), auxiliary carry flag (AC), overflow flag
(OV), power down flag (PDF), and watchdog time-out flag (TO). These arithmetic/logical operation
and system management flags are used to record the status and operation of the microcontroller.
With the exception of the TO and PDF flags, bits in the status register can be altered by instructions like
most other registers. Any data written into the status register will not change the TO or PDF flag. In
addition, operations related to the status register may give different results due to the different
instruction operations. The TO flag can be affected only by a system power-up, a WDT time-out or by
executing the ²CLR WDT² or ²HALT² instruction. The PDF flag is affected only by executing the
²HALT² or ²CLR WDT² instruction or during a system power-up.
The Z, OV, AC and C flags generally reflect the status of the latest operations.
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
interrupt routine can change the status register, precautions must be taken to correctly save it. Note that
bits 0~3 of the STATUS register are both readable and writeable bits.
· STATUS Register
Bit
Name
R/W
POR
Bit 7, 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
7
6
5
4
3
2
1
0
¾
¾
TO
PDF
OV
Z
AC
C
¾
¾
R
R
R/W
R/W
R/W
R/W
¾
¾
0
0
x
x
x
x
²x² unknown
unimplemented, read as ²0²
TO: Watchdog Time-Out flag
0: After power up or executing the ²CLR WDT² or ²HALT² instruction
1: A watchdog time-out occurred.
PDF: Power down flag
0: After power up or executing the ²CLR WDT² instruction
1: By executing the ²HALT² instruction
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.
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
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
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.
Rev. 1.10
33
October 23, 2012
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