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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Reset and Initialisation
Reset and Initialisation
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
7
6
5
4
3
2
1
0
Label
—
LRF
WRF
—
CMP0F
LVRF
XRSTF
PORF
R/W
—
R
R
—
R
R
R
R
POR
—
0
0
—
0
x
0
1
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
Unimplemented, read as “0”
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