HT85F2270 datasheet(77/226 Pages) HOLTEK

77 / 226 page

Rev. 1.00

77 of ��6

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Standard 8051 8-Bit Flash MCU

HT85F2260/HT85F2270/HT85F2280

Reset Operations

After the initial power on reset, there are many ways in which a microcontroller reset can occur,

through events occurring both internally and externally.

Reset Source Register – RSTSRC

After a reset occurs the device will be reset to some initial condition. Several registers are used to

indicate which actual reset type caused the device to reset. Seven of the possible reset sources will

be indicated by the reset source register, RSTSRC. The additional reset sources are indicated by the

SRSTREQ bit in the SRST register for the Software Reset and the WDTS bit in the IP0 register for

the Watchdog reset. And the MCU reset can also caused by ROM Code Check.

All of the bits in the RSTSRC register are read only and can therefore not be cleared by the

application program after one of the relevant reset occurs. After one of these reset occurs and the

relevant bit is high to indicate its occurrence, the bit can only be cleared by hardware when another

different reset type occurs.

RSTSRC Register

SFR Address: FFh

Bit

Label

—

LRF

WRF

�CDF

C�P0F

LVRF

XRSTF

PORF

R/W

—

POR

—

Bit 7

Unimplemented, read as “0”

Bit 6

LRF: LVRCR Register Setting Software Reset Indication Flag

0: No LVRCR Setting Software Reset

1: LVRCR Software Reset

Bit 5

WRF: WDTCR Register Setting Software Reset Indication Flag

0: No WDTCR Setting Software Reset

1: WDTCR Setting Software Reset

Bit 4

MCDF: Missing Clock Detection Reset Indication Flag

0: No Missing Clock Detection Reset

1: Missing Clock Detection Reset

Bit 3

CMP0F: Comparator 0 Reset Indication Flag

0: No Comparator 0 Reset

1: Comparator 0 Reset

Bit 2

LVRF: Low-Voltage Reset Indication Flag

0: No Low-Voltage Reset

1: Low-Voltage Reset

Bit 1

XRSTF: External Pin Reset Indication Flag

0: No External Reset

1: External Reset

Bit 0

PORF: Power-on Reset Indication Flag

0: No Power-on Reset

1: Power-on Reset

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