M16CSLASH29 datasheet(473/499 Pages) RENESAS

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22. Usage Notes

page 449

22.15.9 Interrupts

EW Mode 0

• Any interrupt which has a vector in the variable vector table can be used providing that its vector is

transferred into the RAM area.

_______

• The NMI and watchdog timer interrupts can be used because the FMR0 register and FMR1 register

are initialized when one of those interrupts occurs. The jump addresses for those interrupt service

routines should be set in the fixed vector table.

_______

Because the rewrite operation is halted when a NMI or watchdog timer interrupt occurs, the rewrite

program must be executed again after exiting the interrupt service routine.

• The address match interrupt cannot be used because the flash memory’s internal data is referenced.

EW Mode 1

• Make sure that any interrupt which has a vector in the variable vector table or address match inter-

rupt will not be accepted during the auto program period or auto erase period with erase-suspend

function disabled.

_______

• The NMI interrupt can be used because the FMR0 register and FMR1 register are initialized when

this interrupt occurs. The jump address for the interrupt service routine should be set in the fixed

vector table.

_______

Because the rewrite operation is halted when a NMI interrupt occurs, the rewrite program must be

executed again after exiting the interrupt service routine.

22.15.10 How to Access

To set the FMR01, FMR02, FMR11 or FMR16 bit to 1, set the subject bit to 1 immediately after setting to

0. Do not generate an interrupt or a DMA transfer between the instruction to set the bit to 0 and the

_______

instruction to set the bit to 1. Set the bit when the PM24 bit is set to 1 (NMI funciton) and an high-level (“H”)

_______

signal is applied to the NMI pin.

22.15.11 Writing in the User ROM Area

EW Mode 0

• If the power supply voltage drops while rewriting any block in which the rewrite control program is

stored, a problem may occur that the rewrite control program is not correctly rewritten and, conse-

quently, the flash memory becomes unable to be rewritten thereafter. In this case, standard serial I/

O or parallel I/O mode should be used.

EW Mode 1

• Avoid rewriting any block in which the rewrite control program is stored.

22.15.12 DMA Transfer

In EW mode 1, make sure that no DMA transfers will occur while the FMR00 bit in the FMR0 register is set

to 0(during the auto program or auto erase period).

22.15.13 Regarding Programming/Erasure Times and Execution Time

As the number of programming/erasure times increases, so does the execution time for software com-

mands (Program, and Block Erase).

The software commands are aborted by hardware reset 1, brown-out detection reset (hardware reset 2),

_______

NMI interrupt, and watchdog timer interrupt. If a software command is aborted by such reset or interrupt,

the affected block must be erased before reexecuting the aborted command.

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