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HT48R066B 参数 Datasheet PDF下载

HT48R066B图片预览
型号: HT48R066B
PDF下载: 下载PDF文件 查看货源
内容描述: 增强I / O型8位OTP MCU [Enhanced I/O Type 8-Bit OTP MCU]
分类和应用:
文件页数/大小: 84 页 / 469 K
品牌: HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
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HT48R063B/064B/065B/066B  
Program Counter  
Counter are pushed onto the stack. At the end of a sub-  
routine or an interrupt routine, signaled by a return in-  
struction, RET or RETI, the Program Counter is restored  
to its previous value from the stack. After a device reset,  
the Stack Pointer will point to the top of the stack.  
During program execution, the Program Counter is used  
to keep track of the address of the next instruction to be  
executed. It is automatically incremented by one each  
time an instruction is executed except for instructions,  
such as ²JMP² or ²CALL² that demand a jump to a  
non-consecutive Program Memory address. Note that  
the Program Counter width varies with the Program  
Memory capacity depending upon which device is se-  
lected. However, it must be noted that only the lower 8  
bits, known as the Program Counter Low Register, are  
directly addressable by user.  
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When executing instructions requiring jumps to  
non-consecutive addresses such as a jump instruction,  
a subroutine call, interrupt or reset, etc., the  
microcontroller manages program control by loading the  
required address into the Program Counter. For condi-  
tional skip instructions, once the condition has been  
met, the next instruction, which has already been  
fetched during the present instruction execution, is dis-  
carded and a dummy cycle takes its place while the cor-  
rect instruction is obtained.  
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4
Device  
Stack Levels  
HT48R063B  
2
HT48R064B  
HT48R065B  
HT48R066B  
4
If the stack is full and an enabled interrupt takes place,  
the interrupt request flag will be recorded but the ac-  
knowledge signal will be inhibited. When the Stack  
Pointer is decremented, by RET or RETI, the interrupt  
will be serviced. This feature prevents stack overflow al-  
lowing the programmer to use the structure more easily.  
However, when the stack is full, a CALL subroutine in-  
struction can still be executed which will result in a stack  
overflow. Precautions should be taken to avoid such  
cases which might cause unpredictable program  
branching.  
Program Counter  
Device  
Program Counter  
PCL Register  
High Byte  
HT48R063B  
PC9,PC8  
HT48R064B  
PCL7~PCL0  
HT48R065B  
HT48R066B  
PC10~PC8  
PC11~PC8  
The lower byte of the Program Counter, known as the  
Program Counter Low register or PCL, is available for  
program control and is a readable and writeable regis-  
ter. By transferring data directly into this register, a short  
program jump can be executed directly, however, as  
only this low byte is available for manipulation, the  
jumps are limited to the present page of memory, that is  
256 locations. When such program jumps are executed  
it should also be noted that a dummy cycle will be in-  
serted.  
Arithmetic and Logic Unit - ALU  
The arithmetic-logic unit or ALU is a critical area of the  
microcontroller that carries out arithmetic and logic op-  
erations of the instruction set. Connected to the main  
microcontroller data bus, the ALU receives related in-  
struction codes and performs the required arithmetic or  
logical operations after which the result will be placed in  
the specified register. As these ALU calculation or oper-  
ations may result in carry, borrow or other status  
changes, the status register will be correspondingly up-  
dated to reflect these changes. The ALU supports the  
following functions:  
The lower byte of the Program Counter is fully accessi-  
ble under program control. Manipulating the PCL might  
cause program branching, so an extra cycle is needed  
to pre-fetch. Further information on the PCL register can  
be found in the Special Function Register section.  
·
·
·
Arithmetic operations: ADD, ADDM, ADC, ADCM,  
SUB, SUBM, SBC, SBCM, DAA  
Stack  
Logic operations: AND, OR, XOR, ANDM, ORM,  
XORM, CPL, CPLA  
This is a special part of the memory which is used to  
save the contents of the Program Counter only. The  
stack is neither part of the Data or Program Memory  
space, and is neither readable nor writeable. The acti-  
vated level is indexed by the Stack Pointer, SP, and is  
neither readable nor writeable. At a subroutine call or in-  
terrupt acknowledge signal, the contents of the Program  
Rotation RRA, RR, RRCA, RRC, RLA, RL, RLCA,  
RLC  
·
·
Increment and Decrement INCA, INC, DECA, DEC  
Branch decision, JMP, SZ, SZA, SNZ, SIZ, SDZ,  
SIZA, SDZA, CALL, RET, RETI  
Rev. 1.00  
16  
April 7, 2011