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MC80F0104/0204
Preliminary
98
Mar. 2005 Ver 0.2
21. POWER FAIL PROCESSOR
TheMC80F0104/0204 has an on-chip power fail detection
circuitry to immunize against power noise. A configura-
tion register, PFDR, can enable or disable the power fail
detect circuitry. Whenever V
DD
falls close to or below
power fail voltage for 100ns, the power fail situation may
reset or freeze MCU according to PFDM bit of PFDR. Re-
fer to “Figure 21-1 Power Fail Voltage Detector Register”
In the in-circuit emulator, power fail function is not imple-
mented and user can not experiment with it. Therefore, af-
ter final development of user program, this function may
be experimented or evaluated.
Figure 21-1 Power Fail Voltage Detector Register
Figure 21-2 Example S/W of Reset flow by Power fail
PFDM
7
6
5
4
3
2
1
0
PFDS
INITIAL VALUE: ---- -000
B
ADDRESS: 0F7
H
PFDR
R/W
R/W
R/W
PFDEN
PFD Operation Mode
0 : MCU will be frozen by power fail detection
1 : MCU will be reset by power fail detection
PFD Enable Bit
0: Power fail detection disable
1: Power fail detection enable
Power Fail Status
0: Normal operate
1: Set to “1” if power fail is detected
* Cautions :
Be sure to set bits 3 through 7 to “0”.
-
-
-
-
-
Function
Execution
Initialize RAM Data
PFDS =1
NO
RESET VECTOR
Initialize All Ports
Initialize Registers
RAM Clear
YES
Skip the
initial routine
PFDS = 0
Содержание MC80F0104
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