M16CSLASH1N datasheet(232/238 Pages) RENESAS

232 / 238 page

Rev.1.00

Oct 20, 2004

page 220 of 222

M16C/1N Group

REJ090007-0100Z

20. Precautionary Notes in Using the Device

20.9.8 Prohibited Instructions

The following instructions cannot be used in EW0 mode because the CPU tries to read data in

flash memory: UND instruction, INTO instruction, JMPS instruction, JSRS instruction, and BRK

instruction

20.9.9 Interrupt

EW0 Mode

To use interrupts having vectors in a relocatable vector table, the vectors must be relocated to

the RAM area.

• The watchdog timer interrupt is available since the FMR0 and FMR1 registers are forcibly reset

when either interrupt request is generated. Allocate the jump addresses for each interrupt ser-

vice routines to the fixed vector table. Flash memory rewrite operation is aborted when the

watchdog timer interrupt request is generated. Execute the rewrite program again after exiting

the interrupt routine.

• The address match interrupt is not available since the CPU tries to read data in the flash

memory.

EW1 Mode

• Do not acknowledge any interrupts with vectors in the relocatable vector table or address match

interrupt during the auto program or auto erase period.

• Do not use the watchdog timer interrupt.

20.9.10 How to Access

To set the FMR01, FMR02 or FMR11 bit to "1", write "1" after first setting the bit to "0". Do not

generate an interrupt between the instruction to set the bit to "0" and the instruction to set the bit to

"1".

20.9.11 Rewriting in User ROM Area

EW0 Mode

The supply voltage drops while rewriting the block where the rewrite control program is stored,

the flash memory cannot be rewritten because the rewrite control program is not correctly rewrit-

ten. If this error occurs, rewrite the user ROM area while in standard serial I/O mode, parallel I/

O mode, or CAN I/O mode.

EW1 Mode

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

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