HT48RA0-5 Holtek Semiconductor, HT48RA0-5 Datasheet - Page 5

• Manufacturer Part Number: HT48RA0-5
• Description: Remote Type 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

Functional Description
Execution Flow
The main system clock is derived from either an external
crystal oscillator which requires the connection of the
external crystal or resonator or an internal RC oscillator
which requires no external component for its operation.
It is internally divided into four non-overlapping clocks.
One instruction cycle consists of four system clock cy-
cles.
Instruction fetching and execution are pipelined in such
a way that a fetch takes one instruction cycle while de-
coding and execution takes the next instruction cycle.
However, the pipelining scheme causes each instruc-
tion to effectively execute within one cycle. If an instruc-
tion changes the program counter, two cycles are
required to complete the instruction.
Program Counter - PC
The 10-bit program counter (PC) controls the sequence
in which the instructions stored in program memory are
executed and its contents specify a maximum of 1024
addresses.
Note:
Rev.1.00
Initial reset
Skip
Loading PCL
Jump, call branch
Return from subroutine
*9~*0: Program counter bits
#9~#0: Instruction code bits
Mode
S9
#9
*9
*9
0
#8
S8
*8
*8
0
@7
#7
S7
*7
Program Counter
0
Execution Flow
@6
#6
S6
*6
5
0
Program Counter + 2
After accessing a program memory word to fetch an in-
struction code, the contents of the program counter are
incremented by one. The program counter then points to
the memory word containing the next instruction code.
When executing a jump instruction, conditional skip ex-
ecution, loading PCL register, subroutine call, initial re-
set or return from subroutine, the PC manipulates the
program transfer by loading the address corresponding
to each instruction.
The conditional skip is activated by instruction. Once the
condition is met, the next instruction, fetched during the
current instruction execution, is discarded and a dummy
cycle replaces it to get the proper instruction. Otherwise
proceed with the next instruction.
The lower byte of the program counter (PCL) is a read-
able and writeable register (06H). Moving data into the
PCL performs a short jump. The destination will be
within 256 locations.
When a control transfer takes place, an additional
dummy cycle is required.
S9~S0: Stack register bits
@7~@0: PCL bits
Program Counter
@5
S5
#5
*5
0
@4
S4
#4
*4
0
@3
S3
#3
*3
0
@2
S2
#2
*2
0
HT48RA0-5
March 23, 2010
@1
S1
#1
*1
0
www.DataSheet4U.com
@0
S0
#0
*0
0