MC80F0204 Datasheet, PDF (102/126 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC80F0104/0204
Preliminary
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”
on page 98.
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.
PFDR
R/W R/W R/W
7
6
5
4
3
2
1
0
-
-
-
-
- PFDEN PFDM PFDS
ADDRESS: 0F7_H
INITIAL VALUE: ---- -000_B
Power Fail Status
0: Normal operate
1: Set to “1” if power fail is detected
PFD Operation Mode
0 : MCU will be frozen by power fail detection
1 : MCU will be reset by power fail detection
* Cautions : Be sure to set bits 3 through 7 to “0”.
PFD Enable Bit
0: Power fail detection disable
1: Power fail detection enable
Figure 21-1 Power Fail Voltage Detector Register
RESET VECTOR
PFDS =1
YES
NO
RAM Clear
Initialize RAM Data
Initialize All Ports
Initialize Registers
PFDS = 0
Skip the
initial routine
Function
Execution
Figure 21-2 Example S/W of Reset flow by Power fail
98
Mar. 2005 Ver 0.2