HT46RU25 Holtek Semiconductor Inc., HT46RU25 Datasheet - Page 8

• Manufacturer Part Number: HT46RU25
• Description: Ht46ru25/ht46cu25 -- A/d Type 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

manages the program transfer by loading the address
corresponding to each instruction.
The conditional skip is activated by instructions. Once
the condition is met, the next instruction, fetched during
the current instruction execution, is discarded and a
dummy cycle replaces it to get a proper instruction; oth-
erwise proceed to the next instruction.
The lower byte of the PC (PCL) is a readable and
writeable register (06H). Moving data into the PCL per-
forms a short jump. The destination is within 256 loca-
tions.
When a control transfer takes place, an additional
dummy cycle is required.
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 16384 16 bits format which are addressed by the
program counter and table pointer. The ROM memory is
divided into two banks (Bank0 and Bank1). Each ROM
Note: *13~*0: Table location bits
Rev. 1.30
TABRDC [m]
TABRDL [m]
Instruction
@7~@0: Table pointer bits
Program Memory
111111
*13~*8
TBHP
@7
@7
*7
@6
@6
*6
Table Location
8
@5
@5
*5
Table Location
bank has 8192 16 bit and is selected by setting the
bank pointer (BP.5; Bank0, BP=000XXXXXB; Bank1:
BP=001XXXXXB). The JMP and CALL instructions pro-
vide only 13 bits of address to allow branching within
any 8K program memory. When doing a JMP or CALL
instruction, the user must ensure that the bank pointer
bit (BP.5) is programmed so that the desire program
memory bank is addressed. If a return from a CALL in-
struction or interrupt is executed, the entire 14 bit pro-
gram counter is popped off the stack. Therefore,
manipulation of the BP.5 is not required for the RET or
RETI instructions.
Certain locations in the ROM are reserved for special
usage:
TBHP: Table pointer higher-order bits
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.
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 UART Bus interrupt
service program. If the UART Bus interrupt resulting
from transmission flag or reception is completed, and
if the interrupt is enabled and the stack is not full, the
program begins execution at location 010H.
@4
@4
*4
@3
@3
*3
HT46RU25/HT46CU25
@2
@2
*2
@1
@1
*1
March 9, 2007
@0
@0
*0