HT85F2240 datasheet(74/147 Pages) HOLTEK

74 / 147 page

Rev. 1.10

74 of 147

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A/D Flash 8051 Core Low Pin Count MCU

HT85F2230/HT85F2240

LVRCR Register Software Reset

An LVRCR software reset will be generated when a value other than “01010101”, “00110011”,

“10011001” and “10101010”, exist in the LVRCR register. The LRF bit in the RSTSRC register

will be set high when this occurs, thus indicating the generation of a LVRCR software reset. The

LVRCR register value will be rest to a value of 00110011B after any reset other than the LVR reset,

and will remain unchanged after an LVR reset.

LVRCR Register

SFR Address: EAh

Bit

Name

LVS7

LVS6

LVS�

LVS4

LVS�

LVS1

LVS0

R/W

POR

Bit 7 ~ 0

LVS7 ~ LVS0: LVR Voltage Select control

01010101: 2.1V

00110011: 2.55V (default)

10011001: 3.15V

10101010: 4.0V

Any other value: Generates MCU reset – register is reset to POR value

Reset Initial Conditions

The different types of reset described affect the reset flags in different ways. The following table

indicates the way in which the various components of the microcontroller are affected after a

power-on reset occurs.

Item

Condition After Reset

Program Co�nter

Reset to zero

Interr�pts

A�� interr�pts wi�� be disab�ed

WDT

C�ear after reset� WDT begins co�nting

Timer/Even Co�nters

Timer/Even Co�nters wi�� be t�rned off

Inp�t/O�tp�t Ports

I/O ports wi�� be set�p as a q�asi-bidirection str�ct�re

Stack Pointer

Set to 007H va��e

The different kinds of resets all affect the internal registers of the microcontroller in different ways.

To ensure reliable continuation of normal program execution after a reset occurs, it is important to

know what condition the microcontroller is in after a particular reset occurs. The following table

describes how each type of reset affects each of the microcontroller internal registers.

HT85F2240 Datasheet(PDF) 74 Page - Holtek Semiconductor Inc

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