HT46R4A
·
·
·
Location 008H
Arithmetic and Logic Unit - ALU
This internal vector is used by the Timer/Event Coun-
ter 0. If a counter overflow occurs, the program will
jump to this location and begin execution if the
timer/event counter interrupt is enabled and the stack
is not full.
The arithmetic-logic unit or ALU is a critical area of the
microcontroller that carries out arithmetic and logic op-
erations of the instruction set. Connected to the main
microcontroller data bus, the ALU receives related in-
struction codes and performs the required arithmetic or
logical operations after which the result will be placed in
the specified register. As these ALU calculation or oper-
ations may result in carry, borrow or other status
changes, the status register will be correspondingly up-
dated to reflect these changes. The ALU supports the
following functions:
Location 00CH
This internal vector is used by the Timer/Event Coun-
ter 1. If a counter overflow occurs, the program will
jump to this location and begin execution if the
timer/event counter interrupt is enabled and the stack
is not full.
Location 010H
This internal vector is used by the A/D converter.
When an A/D conversion cycle is complete, the pro-
gram will jump to this location and begin execution if
the A/D interrupt is enabled and the stack is not full.
·
·
·
Arithmetic operations: ADD, ADDM, ADC, ADCM,
SUB, SUBM, SBC, SBCM, DAA
Logic operations: AND, OR, XOR, ANDM, ORM,
XORM, CPL, CPLA
0
0
0
0
0
0
0
4
8
H
H
H
Rotation RRA, RR, RRCA, RRC, RLA, RL, RLCA,
RLC
I
n
i
t
i
a
l
i
s
a
t
i
o
n
V
e
c
t
o
r
E
x
t
e
r
n
a
l
I
n
t
e
r
r
u
p
t
V
e
c
t
o
r
·
·
Increment and Decrement INCA, INC, DECA, DEC
Branch decision, JMP, SZ, SZA, SNZ, SIZ, SDZ,
SIZA, SDZA, CALL, RET, RETI
T
i
m
e
r
/
E
v
e
n
t
C
o
u
n
t
e
r
0
I
n
t
e
r
r
u
p
t
V
e
c
t
o
r
0
0
C
H
T
i
m
e
r
/
E
v
e
n
t
C
o
u
n
t
e
r
1
I
n
t
e
r
r
u
p
t
V
e
c
t
o
r
Program Memory
P
r
o
g
r
a
m
0
1
0
H
M
e
m
o
r
y
A
/
D
C
o
n
v
e
r
t
e
r
I
n
t
e
r
r
u
p
t
S
u
b
r
o
u
t
i
n
e
The Program Memory is the location where the user code
or program is stored. For this device, the type of memory
is One-Time Programmable, OTP, memory where users
can program their application code into the device. By us-
ing the appropriate programming tools, OTP devices of-
fer users the flexibility to freely develop their applications
which may be useful during debug or for products requir-
ing frequent upgrades or program changes. OTP devices
are also applicable for use in applications that require low
or medium volume production runs.
n
0
0
H
L
o
o
k
-
u
p
T
a
b
l
e
(
2
5
6
w
o
r
d
s
)
n
F
F
H
F
0
0
H
L
o
o
k
-
u
p
T
a
b
l
e
(
2
5
6
w
o
r
d
s
)
F
F
F
H
1
5
b
i
t
s
N
o
t
e
:
n
r
a
n
g
e
s
f
r
o
m
0
t
o
F
Program Memory Structure
Structure
Look-up Table
The Program Memory has a capacity of 4K by 15 bits.
The Program Memory is addressed by the Program
Counter and also contains data, table information and
interrupt entries. Table data, which can be setup in any
location within the Program Memory, is addressed by
separate table pointer registers.
Any location within the Program Memory can be defined
as a look-up table where programmers can store fixed
data. To use the look-up table, the table pointer must
first be setup by placing the lower order address of the
look up data to be retrieved in the table pointer register,
TBLP. This register defines the lower 8-bit address of
the look-up table.
Special Vectors
After setting up the table pointer, the table data can be
retrieved from the current Program Memory page or last
Program Memory page using the ²TABRDC[m]² or
²TABRDL [m]² instructions, respectively. When these in-
structions are executed, the lower order table byte from
the Program Memory will be transferred to the user de-
fined Data Memory register [m] as specified in the in-
struction. The higher order table data byte from the
Program Memory will be transferred to the TBLH special
register. Any unused bits in this transferred higher order
byte will be read as ²0².
Within the Program Memory, certain locations are re-
served for special usage such as reset and interrupts.
·
Location 000H
This vector is reserved for use by the device reset for
program initialisation. After a device reset is initiated, the
program will jump to this location and begin execution.
·
Location 004H
This vector is used by the external interrupt. If the ex-
ternal interrupt pin on the device goes low, the pro-
gram will jump to this location and begin execution if
the external interrupt is enabled and the stack is not
full.
Rev. 1.00
8
November 28, 2007
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
