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Chapter 26
Reset
Preliminary User’s Manual U17566EE1V2UM00
(1)
RESSTAT - Reset source flag register
The 8-bit RESSTAT register contains information about which type of resets
occurred since the last Power-On-Clear or external RESET or after the last
software clear of the register.
Each following reset condition sets the corresponding flag in the register. For
example, if a Power-On-Clear reset is finished and then a Watchdog Timer
reset occurs, the RESSTAT reads xxx1 0001
B
.
Access
The register can be read/written in 8-bit units.
Address
FFFF FF20
H
Initial Value
Power-On-Clear reset sets this register to 01
H
.
External RESET sets this register to 02
H
.
Note
If clearing this register by writing and flag setting (occurrence of reset) conflict,
flag setting takes precedence.
RESPOC and
RESEXT
Both Power-On-Clear and external RESET set RESSTAT to different initial
states.
• Power-On-Clear reset sets RESSTAT = 01
H
• External RESET sets RESSTAT = 02
H
Special caution is required if both reset events are active concurrently:
• If the Power-On-Clear reset is longer active than the external RESET:
RESSTAT = 01
H
. That means RESSTAT indicates only the occurrence of
the Power-On-Clear reset.
• If the external RESET is longer active than the Power-On-Clear reset:
RESSTAT = 02
H
.That means RESSTAT indicates only the occurrence of the
external RESET.
7
6
5
4
3
2
1
0
X
X
X
RESWDT RESCM2 RESCM1 RESEXT RESPOC
R
R
R
a
a)
Any write clears this register, independent of the data written.
R/W
a
R/W
a
R/W
a
R/W
a
R/W
a
Table 26-4
RESSTAT register contents
Bit position
Bit name
Function
4
RESWDT
Reset by Watchdog Timer
0: Not generated.
1: Generated.
3
RESCM2
Reset by Clock Monitor of sub oscillator
0: Not generated.
1: Generated.
2
RESCM1
Reset by Clock Monitor of main oscillator
0: Not generated.
1: Generated.
1
RESEXT
External RESET
0: Not generated.
1: Generated.
0
RESPOC
Reset at Power-On-Clear
0: Not generated.
1: Generated.
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