Program Memory; Str�Ct�Re; Special Vectors; Look-�P Table - Holtek HT46R003B Manual

HT46R003B
Cost-Effective A/D 8-bit OTP MCU

Program Memory

The Program Memory is the location where the user code or program is stored. The device is
supplied with One-Time Programmable, OTP, memory where users can program their application
code into the device. By using the appropriate programming tools, OTP device offers users the
flexibility to freely develop their applications which may be useful during debug or for products
requiring frequent upgrades or program changes.
Structure
The Program Memory has a capacity of 1K×14 bits. The Program Memory is addressed by the
Program Counter and also contains data, table information and interrupt entries information. Table
data, which can be set in any location within the Program Memory, is addressed by separate table
pointer register.

Special Vectors

Within the Program Memory, certain locations are reserved for the reset and interrupts. The location
000H 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.
Look-up Table
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 set by placing the address
of the look up data to be retrieved in the table pointer register, TBLP. This register defines the total
address of the look-up table.
After setting up the table pointer, the table data can be retrieved from the Program Memory
using the "TABRDC [m]" or "TABRDL [m]" instructions, respectively. When the instruction is
executed, the lower order table byte from the Program Memory will be transferred to the user
defined Data Memory register [m] as specified in the instruction. 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 "0".
The accompanying diagram illustrates the addressing data flow of the look-up table.
Rev. 1.00
000H
Initialisation Vector
00�H
Interr�pt Vectors
010H
n00H
Look-�p Table
nFFH
1� bits
3FFH
Program Memory Structure
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