HT46R068B/HT46R069B
Enhanced A/D Type 8-bit OTP MCU
Input/Output Ports and Control Registers
Within the area of Special Function Registers, the port PA, PB, etc data I/O registers and their
associated control register PAC, PBC, etc play a prominent role. These registers are mapped to
specific addresses within the Data Memory as shown in the Data Memory table. The data I/O
registers, are used to transfer the appropriate output or input data on the port. The control registers
specifies which pins of the port are set as inputs and which are set as outputs. To setup a pin as
an input, the corresponding bit of the control register must be set high, for an output it must be
set low. During program initialisation, it is important to first setup the control registers to specify
which pins are outputs and which are inputs before reading data from or writing data to the I/
O ports. One flexible feature of these registers is the ability to directly program single bits using
the "SET [m].i" and "CLR [m].i" instructions. The ability to change I/O pins from output to input
and vice versa by manipulating specific bits of the I/O control registers during normal program
operation is a useful feature of these devices.
● STATUS Register
Bit
Name
R/W
7
6
5
TO
R
4
PDF
R
3
OV
R/W
X
2
Z
R/W
X
1
AC
R/W
X
0
C
R/W
X
—
—
—
—
—
—
POR
0
0
"X" ꢀnknown
Bit 7,6
Unimplemented, read as "0"
Bit 5
Bit 4
Bit 3
TO: Watchdog Time-Out flag
0: After power up or executing the "CLR WDT" or "HALT" instruction
1: A watchdog time-out occured.
PDF: Power down flag
0: After power up or executing the "CLR WDT" instruction
1: By executing the "HALT" 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
thehighest-order bit or vice versa.
Bit 2
Bit 1
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 not 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
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
C is also affected by a rotate through carry instruction.
Rev. 1.00
ꢃ5
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HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
