Renesas M34502T-MCU - Manual (Page 30)

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RC
INY
EPOF
POF
•
•
Actual MCU
The RAM backup mode works.
M34502T-MCU
The RAM backup mode works.
RC
INY
POF
•
•
•
Actual MCU
The RAM backup mode does NOT work.
M34502T-MCU
The RAM backup mode works.
5.8 RAM Backup Mode
In the RAM backup mode, the M34502T-MCU operates differently from actual MCUs.
(1) On Port Output (Ports D, P0 and P1) in the RAM Backup Mode
With an actual MCU, the state of ports immediately before the RAM backup mode is retained,
while with the M34502T-MCU, it is not retained. (a restriction of the M34502T-MCU)
With the M34502T-MCU, in the RAM backup mode, ports D, P0 and P1 are held HIGH, and when
returned from the RAM backup mode they retain their previous state.
Therefore, to evaluate a system which needs ports D, P0 and P1 to be held LOW in the RAM
backup mode, you need an evaluation MCU (OTP version).
(2) RAM Operation of the M34502T-MCU
Though the actual chip is placed in the RAM backup mode by executing a combination of "EPOF"
and "POF" or "POF2" instructions, the M34502T-MCU is placed in the RAM backup mode by
only either "POF" instruction or "POF2" instruction.
In the M34502T-MCU, the "EPOF" instruction does not have any effect.
Program example 5.1
Program example 5.2