HT46R71D-1 Holtek Semiconductor, HT46R71D-1 Datasheet - Page 9

• Manufacturer Part Number: HT46R71D-1
• Description: Dual Slope A/D Type MCU
• Manufacturer: Holtek Semiconductor

www.DataSheet4U.com
Data Memory - RAM
Bank 0 of the data memory has a capacity of 59 8 bits,
and is divided into two functional groups, namely the
special function registers of 27 8 bit capacity and the
general purpose data memory of 32 8 bit capacity. Most
locations are readable/writable, although some are read
only. The special function register are overlapped in all
banks.
Any unused space before 20H is reserved for future ex-
panded usage, reading these locations will get 00H .
The general purpose data memory, addressed from 20H
to 3FH , is used for data and control information under
instruction commands. All of the data memory areas can
handle arithmetic, logic, increment, decrement and ro-
tate operations directly. Except for some dedicated bits,
each bit in the data memory can be set and reset by the
indirectly accessible through the memory pointer regis-
ters, MP0 and MP1.
Rev. 1.00
SET [m].i and CLR [m].i instructions. They are also
RAM Mapping
9
Bank 1 contains the LCD Data Memory locations. After
first setting up BP to the value of 01H to access Bank 1
this bank must then be accessed indirectly using the
Memory Pointer MP1. With BP set to a value of 01H ,
using MP1 to indirectly read or write to the data memory
areas with addresses from 40H~49H will result in opera-
tions to Bank 1. Directly addressing the Data Memory
will always result in Bank 0 being accessed irrespective
of the value of BP.
Indirect Addressing Register
Location 00H and 02H are indirect addressing registers
that are not physically implemented. Any read/write op-
eration of [00H] and [02H] accesses the RAM pointed to
by MP0 (01H) and MP1 (03H) respectively. Reading lo-
cation 00H or 02H indirectly returns the result 00H.
While, writing it indirectly leads to no operation. The
memory pointer register (MP0, MP1) are 7-bit registers.
The function of data movement between two indirect ad-
dressing registers is not supported. The memory pointer
registers, MP0 and MP1, are both 7-bit registers used to
access the RAM by combining corresponding indirect
addressing registers. MP0 can only be applied to data
memory, while MP1 can be applied to data memory and
LCD display memory.
Accumulator - ACC
The accumulator (ACC) is related to the ALU opera-
tions. It is also mapped to location 05H of the RAM and
is capable of operating with immediate data. The data
movement between two data memory locations must
pass through the ACC.
Arithmetic and Logic Unit - ALU
This circuit performs 8-bit arithmetic and logic opera-
tions and provides the following functions:
The ALU not only saves the results of a data operation
but also changes the status register.
Status Register - STATUS
The status register (0AH) is 8 bits wide and contains, a
carry flag (C), an auxiliary carry flag (AC), a zero flag (Z),
an overflow flag (OV), a power down flag (PDF), and a
watchdog time-out flag (TO). It also records the status
information and controls the operation sequence.
Except for the TO and PDF flags, bits in the status regis-
ter can be altered by instructions similar to other regis-
ters. Data written into the status register does not alter
the TO or PDF flags. Operations related to the status
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 etc.)
HT46R71D-1
May 14, 2007