M16C62P_06 Datasheet, PDF (395/421 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

M16C/62P Group (M16C/62P, M16C/62PT)
24. Precautions
24.15.8 Operation speed
Before entering CPU rewrite mode (EW0 or EW1 mode), set the CM11 bit in the CM1 register to “0” (main
clock), select 10 MHz or less for CPU clock using the CM06 bit in the CM0 register and CM17 to CM16 bits in
the CM1 register. Also, set the PM17 bit in the PM1 register to “1” (with wait state).
24.15.9 Instructions inhibited against use
The following instructions cannot be used in EW0 mode because the flash memory’s internal data is referenced:
UND instruction, INTO instruction, JMPS instruction, JSRS instruction, and BRK instruction.
24.15.10 Interrupts
EW0 Mode
• Any interrupt which has a vector in the relocatable 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.
EW1 Mode
• Make sure that any interrupt which has a vector in the variable vector table or address match interrupt will
not be accepted during the auto program or auto erase period.
• Avoid using watchdog timer interrupts.
• 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.
24.15.11 How to access
To set the FMR01, FMR02, or FMR11 bit to “1”, write “0” and then “1” in succession. This is necessary to
ensure that no interrupts or DMA transfers will occur before writing “1” after writing “0”. Also only when NMI
pin is “H” level.
24.15.12 Writing in the user ROM area
EW0 Mode
• 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, consequently, the flash
memory becomes unable to be rewritten thereafter. In this case, standard serial I/O or parallel I/O mode
should be used.
EW1 Mode
• Avoid rewriting any block in which the rewrite control program is stored.
Rev.2.41 Jan 10, 2006 Page 380 of 390
REJ09B0185-0241