HT46R016 datasheet(21/91 Pages) HOLTEK

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HT46R016/HT46R017

Enhanced A/D 8-Bit OTP MCU

Accumulator – ACC

The Accumulator is central to the operation of any microcontroller and is closely related with

operations carried out by the ALU. The Accumulator is the place where all intermediate results

from the ALU are stored. Without the Accumulator it would be necessary to write the result of

each calculation or logical operation such as addition, subtraction, shift, etc., to the Data Memory

resulting in higher programming and timing overheads. Data transfer operations usually involve

the temporary storage function of the Accumulator; for example, when transferring data between

one user-defined register and another, it is necessary to do this by passing the data through the

Accumulator as no direct transfer between two registers is permitted.

Program Counter Low Register – PCL

To provide additional program control functions, the low byte of the Program Counter is made

accessible to programmers by locating it within the Special Purpose area of the Data Memory. By

manipulating this register, direct jumps to other program locations are easily implemented. Loading

a value directly into this PCL register will cause a jump to the specified Program Memory location,

however as the register is only 8-bit wide only jumps within the current Program Memory page are

permitted. When such operations are used, note that a dummy cycle will be inserted.

Status Register – STATUS

This 8-bit register contains the zero flag (Z), carry flag (C), auxiliary carry flag (AC), overflow flag

(OV), power down flag (PDF), and watchdog time-out flag (TO). These arithmetic/logical operation

and system management flags are used to record the status and operation of the microcontroller.

With the exception of the TO and PDF flags, bits in the status register can be altered by instructions

like most other registers. Any data written into the status register will not change the TO or PDF flag.

In addition, operations related to the status register may give different results due to the different

instruction operations. The TO flag can be affected only by a system power-up, a WDT time-out or

by executing the “CLR WDT” or “HALT” instruction. The PDF flag is affected only by executing

the “HALT” or “CLR WDT” instruction or during a system power-up.

The Z, OV, AC and C flags generally reflect the status of the latest operations.

In addition, on entering an interrupt sequence or executing a subroutine call, the status register will

not be pushed onto the stack automatically. If the contents of the status registers are important and

if the subroutine can corrupt the status register, precautions must be taken to correctly save it. Note

that bits 0~3 of the STATUS register are both readable and writeable bits.

HT46R016 数据表(PDF) 21 Page - Holtek Semiconductor Inc

HT46R016 数据表(HTML) 21 Page - Holtek Semiconductor Inc

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