R8C2K datasheet(407/471 Pages) RENESAS

407 / 471 page

R8C/2K Group, R8C/2L Group

20. Flash Memory

Rev.1.10

Dec 21, 2007

Page 390 of 450

REJ09B0406-0110

20.4.4.2

Suspend Function

The suspend function halts auto-erasure and auto-programming temporarily while these operations are in

progress. This function is used for interrupt handling as the user ROM area can be read after the above

operations have been suspended.

When the suspend function is used in EW1 mode, the MCU enters erase-suspend or program-suspend after an

interrupt request is acknowledged.

To enable the suspend function, set the FMR40 bit to 1 (suspend enabled). The interrupt to enter suspend should

also be set to enable beforehand. When td (SR-SUS) has elapsed after the interrupt request is generated, the

request is acknowledged.

When an interrupt request is generated during an erase operation, the FMR41 bit is automatically set to 1 (erase-

suspend request) and the auto-erase operation suspends. If an auto-erase operation does not complete (FMR00

bit is 0) after an interrupt process completes, the auto-erase operation restarts by setting the FMR41 bit to 0

(erasure restarts).

When an interrupt request is generated during an auto-program operation, the FMR42 bit is automatically set to

1 (program-suspend request) and the auto-program operation suspends. When the auto-program operation does

not complete (FMR00 bit is 0) after the interrupt process completes, the auto-program operation can be

restarted by setting the FMR42 bit to 0 (programming restarts).

Figure 20.23 shows the Timing of Suspend Operation in EW1 Mode. Figure 20.24 shows the Program

Flowchart during Erase-Suspend in EW1 Mode.

Figure 20.23

Timing of Suspend Operation in EW1 Mode

FMR00 bit in

FMR0 register

FMR46 bit in

FMR4 register

FMR44 bit in

FMR4 register

FMR43 bit in

FMR4 register

Erasure

starts

Erasure

suspends

Programming

starts

Programming

suspends

Programming

restarts(1)

Programming

ends

During erasure

During programming

Erasure

restarts

Erasure

ends

During erasure

Check the status,

and that the

programming ends

normally.

Check the status,

and that the

erasure ends

normally.

NOTE:

1. If program-suspend is entered during erase-suspend, restart programming first.

The above figure shows an example of the use of program-suspend during programming following erase-suspend.

IR bit in interrupt

control register

Set to 0 when interrupt request is acknowledged, or set by a program.

Check that the

FMR43 bit is set to 1

(during erase

execution), and that

the erase-operation

has not ended.

Check that the

FMR44 bit is set to 1

(during program

execution), and that

the program has not

ended.

Remains 0 during suspend

Remains 1 during suspend

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