Renesas M34502T-MCU 5.8 RAM Backup Mode

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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

Contents

Main ( 2 / 38 ) Contents Page 1. Precautions for Safety WARNING IMPORTANT CAUTION WARNING CAUTION IMPORTANT Notes on Differences between an Actual MCU and the Emulator: Note on the Target System: Notes on Connecting the Target System: Page 2. Handling Precautions Table 2.2 Registers that can be operated for 4580 Group MCUs 3. Contents of the Package 3.1 Package Components of the M34502T-MCU 3.2 Other Necessary Products Page 4. M34502T-MCU 4.1 Outline 4.2 Specifications Table 4.1 lists specifications of the M34502T-MCU. Table 4.1 M34502T-MCU specifications 4.3 Switches Figure 4.3 Positions of switches Table 4.2 Functions of switches Figure 4.4 Positions of the connectors 4.5 Connectors 4.4 Check Pins The M34502T-MCU has check pins listed in Table 4.3. Table 4.3 Check pins Figure 4.5 Connector J3 pin layout Page 4.6 Connecting to the Target System Figure 4.9 Pin layout of the 26-wire normal-pitch cable Table 4.8 26-wire normal-pitch cable pin assignments Page Table 4.9 M34501T-PTC pin assignments Figure 4.11 Pin layout of the M34501T-PTC 4.7 LED Page 5. Precautions to Be Taken When Debugging 5.1 Reset 5.2 System Clock 5.3 Real-time Capability of Timer 5.5 Port I/O Timing 5.4 Watchdog Timer 5.6 Port I/O Characteristics 5.7 Pullup Transistor 5.8 RAM Backup Mode 5.9 Program Execution (G, GB) Page 5.10 External Trigger Signal 5.11 Other Precautions Page Page Page Page Appendix A. How to Request for Repair CAUTION Note on Transporting the Product: