HT46RB50 Holtek Semiconductor, HT46RB50 Datasheet - Page 7

• Manufacturer Part Number: HT46RB50
• Description: A/D Type USB 8-Bit MCU
• Manufacturer: Holtek Semiconductor

Program Memory - EPROM
The program memory (EPROM) is used to store the pro-
gram instructions which are to be executed. It also con-
tains data, table, and interrupt entries, and is organized
into 4096 15 bits which are addressed by the Program
Counter and table pointer.
Certain locations in the ROM are reserved for special
usage:
Note: *11~*0: Table location bits
Rev. 1.10
TABRDC [m]
TABRDL [m]
Location 000H
Location 000H is reserved for program initialization.
After a chip reset, the program always begins execu-
tion at this location.
Location 004H
Location 004H is reserved for the external interrupt
service program. If the INT input pin is activated, and
the interrupt is enabled, and the stack is not full, the
program begins execution at location 004H.
Location 008H
Location 008H is reserved for the Timer/Event Coun-
ter 0 interrupt service program. If a timer interrupt re-
sults from a Timer/Event Counter 0 overflow, and if the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at location 008H.
Instruction
@7~@0: Table pointer bits
Program Memory
P11
*11
1
P10
*10
1
P9
*9
1
P8
*8
1
Table Location
@7
@7
*7
7
Table Location
Stack Register - STACK
This is a special part of the memory which is used to
save the contents of the Program Counter only. The
stack is organized into 6 levels and is neither part of the
data nor part of the program space, and is neither read-
able nor writeable. The activated level is indexed by the
stack pointer (SP) and is neither readable nor writeable.
P11~P8: Current program counter bits
@6
@6
*6
Location 00CH
Location 00CH is reserved for the Timer/Event Coun-
ter 1 interrupt service program. If a timer interrupt re-
sults from a Timer/Event Counter 1 overflow, and if the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at location 00CH.
Location 010H
Location 010H is reserved for the USB interrupt ser-
vice program. If the USB interrupt is activated, the in-
terrupt is enabled and the stack is not full, the program
begins execution at location 010H.
Location 014H
Location 014H is reserved for the A/D converter inter-
rupt service program. If an A/D converter interrupt re-
sults from an end of A/D conversion, and the stack is
not full, the program begins execution at location
014H.
Location 018H
Location 018H is reserved when 8 bits data have been
received or transmitted successfully from serial inter-
face, and the related interrupts are enabled, and the
stack is not full, the program begins execution at loca-
tion 018H.
Table location
Any location in the ROM can be used as a look-up ta-
ble. The instructions TABRDC [m] (the current page,
page=256 words) and TABRDL [m] (the last page)
transfer the contents of the lower-order byte to the
specified data memory, and the contents of the
higher-order byte to TBLH (Table Higher-order byte
register) (08H). Only the destination of the lower-order
byte in the table is well-defined; the other bits of the ta-
ble word are all transferred to the lower portion of
TBLH. The TBLH is read only, and the table pointer
(TBLP) is a read/write register (07H), indicating the ta-
ble location. Before accessing the table, the location
should be placed in TBLP. All the table related instruc-
tions require 2 cycles to complete the operation.
These areas may function as a normal ROM depend-
ing upon users requirements.
@5
@5
*5
@4
@4
*4
@3
@3
*3
@2
@2
*2
September 7, 2006
HT46RB50
@1
@1
*1
@0
@0
*0