HT45R22E Holtek Semiconductor, HT45R22E Datasheet - Page 11

• Manufacturer Part Number: HT45R22E
• Description: Remote Type 8-bit OTP MCU
• Manufacturer: Holtek Semiconductor

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 devices
offer users the flexibility to freely develop their applica-
tions which may be useful during debug or for products
requiring frequent upgrades or program changes.
Structure
The Program Memory has a capacity of 4K 15. 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.
Special Vectors
Within the Program Memory, certain locations are re-
served for special usage such as reset and interrupts.
Rev. 1.00
Reset Vector
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 execu-
tion.
External interrupt vector
This vector is used by the external interrupt. If the ex-
ternal interrupt pin on the device receives an edge
transition, the program will jump to this location and
begin execution if the external interrupt is enabled and
the stack is not full. The external interrupt active edge
transition type, whether high to low, low to high or both
is specified in the CTRL1 register.
HT45R22E
Device
Program Memory Structure
Capacity
4K 15
11
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 0 .
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 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.
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 TABRDC[m] or
TABRDL [m] instructions, respectively. When these in-
Timer/Event 0/1 counter interrupt vector
This internal vector is used by the Timer/Event Coun-
ters. If a Timer/Event Counter overflow occurs, the
program will jump to its respective location and begin
execution if the associated Timer/Event Counter inter-
rupt is enabled and the stack is not full.
Time base interrupt vector
This internal vector is used by the internal Time Base.
If a Time Base overflow occurs, the program will jump
to this location and begin execution if the Time Base
counter interrupt is enabled and the stack is not full.
Multi-function interrupt vector
This vector is used by the OPA0,OPA1 and Compara-
tor. When either an OPA or Comparator, dependent
upon which one is selected, requires interrupt servic-
ing, the program will jump to this location and begin
execution if the output interrupt is enabled and the
stack is not full.
HT45R22E
March 17, 2010
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