![](https://csdnimg.cn/release/download_crawler_static/1787825/bg8.jpg)
HT48R05A-1/HT48C05/HT48R06A-1/HT48C06
Rev. 1.10 8 June 9, 2004
The memory pointer register MP (01H) is a 7-bit register.
The bit 7 of MP is undefined and reading will return the
result ²1². Any writing operation to MP will only transfer
the lower 7-bit data to MP.
Accumulator
The accumulator is closely related to ALU operations. It
is also mapped to location 05H of the data memory and
can carry out immediate data operations. The data
movement between two data memory locations must
pass through the accumulator.
Arithmetic and Logic Unit - ALU
This circuit performs 8-bit arithmetic and logic opera
-
tions. The ALU provides the following functions:
·
Arithmetic operations (ADD, ADC, SUB, SBC, DAA)
·
Logic operations (AND, OR, XOR, CPL)
·
Rotation (RL, RR, RLC, RRC)
·
Increment and Decrement (INC, DEC)
·
Branch decision (SZ, SNZ, SIZ, SDZ ....)
The ALU not only saves the results of a data operation
but also changes the status register.
Status Register - STATUS
This 8-bit register (0AH) 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). It also records the status information and controls
the operation sequence.
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 opera
-
tions related to the status register may give different re
-
sults from those intended. The TO flag can be affected
only by system power-up, a WDT time-out or executing
the ²CLR WDT² or ²HALT² instruction. The PDF flag
can be affected only by executing the ²HALT² or ²CLR
WDT² instruction or a system power-up.
The Z, OV, AC and C flags generally reflect the status of
the latest operations.
In addition, on entering the interrupt sequence or exe-
cuting the subroutine call, the status register will not be
pushed onto the stack automatically. If the contents of
the status are important and if the subroutine can cor-
rupt the status register, precautions must be taken to
save it properly.
Interrupt
The device provides an external interrupt and internal
timer/event counter interrupts. The Interrupt Control
Register (INTC;0BH) contains the interrupt control bits
to set the enable or disable and the interrupt request
flags.
Once an interrupt subroutine is serviced, all the other in
-
terrupts will be blocked (by clearing the EMI bit). This
scheme may prevent any further interrupt nesting. Other
interrupt requests may happen during this interval but
only the interrupt request flag is recorded. If a certain in
-
terrupt requires servicing within the service routine, the
EMI bit and the corresponding bit of INTC may be set to
allow interrupt nesting. If the stack is full, the interrupt re
-
quest will not be acknowledged, even if the related inter
-
rupt is enabled, until the SP is decremented. If
immediate service is desired, the stack must be pre
-
vented from becoming full.
All these kinds of interrupts have a wake-up capability.
As an interrupt is serviced, a control transfer occurs by
pushing the program counter onto the stack, followed by
a branch to a subroutine at specified location in the pro
-
gram memory. Only the program counter is pushed onto
the stack. If the contents of the register or status register
G e n e r a l P u r p o s e
D A T A M E M O R Y
( 6 4 B y t e s )
S p e c i a l P u r p o s e
D A T A M E M O R Y
0 0 H
0 1 H
0 2 H
0 3 H
0 4 H
0 5 H
0 6 H
0 7 H
0 8 H
0 9 H
0 A H
0 B H
0 C H
0 D H
0 E H
0 F H
1 0 H
1 1 H
1 2 H
1 3 H
1 4 H
1 5 H
1 6 H
1 7 H
1 8 H
1 9 H
1 A H
1 B H
1 C H
1 D H
1 E H
1 F H
7 F H
I n d i r e c t A d d r e s s i n g R e g i s t e r
M P
A C C
P C L
T B L P
T B L H
W D T S
S T A T U S
I N T C
T M R
T M R C
P A
P A C
P B
P B C
P C
P C C
: U n u s e d
R e a d a s " 0 0 "
3 F H
4 0 H
2 0 H
H T 4 8 R 0 6 A - 1 / H T 4 8 C 0 6
RAM Mapping for HT48R06A-1/HT48C06