M32CSLASH8B datasheet(323/406 Pages) RENESAS

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M32C/8B Group

23. Flash Memory

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 306 of 385

23.4

Flash Memory Stop Function

When the FMSTP bit in the FMR0 register is set to 1 (flash memory stopped), the flash memory control circuit

stops and as a result power consumption in the flash memory can be reduced. When the FMSTP bit is set to 1

from 0 (flash memory started), the flash memory control circuit is initialized. Access to the flash memory is

disabled when the FMSTP bit is set to 1. Set the FMSTP bit to 1 by the program placed in an area other than the

flash memory.

Set the FMSTP bit to 1 in one of the following cases in accordance with the procedure shown in Figure 23.6.

• A flash memory access error occurs while erasing or programming in EW0 mode (the FMR00 bit does not

switch back to 1 (ready)).

• To further reduce power consumption in low-power consumption mode or on-chip oscillator low-power

consumption mode.

The flash memory is automatically turned off when entering wait mode or stop mode, and turned back on when

exiting wait mode or stop mode. Set the FMR01 bit in the FMR0 register to 0 (CPU rewrite mode disabled)

before entering wait mode or stop mode.

Figure 23.6

Procedure to Stop Flash Memory

Start

End

Transfer the program to the internal RAM

Jump to the program transferred to the internal RAM

FMR0 register: FMR01 bit = 0

FMR0 register: FMR01 bit = 1

CPU rewrite mode enabled

- To set the FMR01 bit to 1, write a 1 to the FMR01 bit

immediately after writing a 0.

Write the value to the FMR0 register in 8-bit units.

Do not generate an interrupt or a DMA or DMACII transfer

between these two settings.

- Set it while "H" is applied to the NMI pin.

Jump to a given address in the flash memory

FMR0 register: FMSTP bit = 1

Flash memory stops operating

(Enters low-power consumption state and a flash memory is initialized)

Switch the CPU clock source

Stop main clock

Oscillate main clock

Switch the CPU clock source

FMR0 register: FMSTP bit = 0

Flash memory starts operating

FMR0 register: FMR01 bit = 0

CPU rewrite mode disabled

- To change the FMR01 bit from 1 to 0, enter read array mode

and then write to address 0057h in 16-bit units.

Set the eight high-order bits to 00h.

Wait for tps

When switching the CPU clock source, wait until the new CPU clock

source stabilizes.

Wait time to stabilize flash memory circuit

- Add tps wait time by a program.

- Do not access the flash memory during this wait time.

Execute the following procedure using the program transferred to the internal RAM

Processing in low-power consumption

mode or on-chip oscillator low-power

consumption mode

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