M16C30P_07 Datasheet, PDF (301/317 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/30 SERIES

M16C/30P Group
22. Usage Precaution
22.14.8 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).
22.14.9 Prohibited instructions
The following instructions cannot be used in EW0 mode because they reference data in the flash memory: UND
instruction, INTO instruction, JMPS instruction, JSRS instruction, and BRK instruction.
22.14.10 Interrupts
EW0 Mode
• To use interrupts having vectors in a relocatable vector table, the vectors must be relocated in the RAM
area.
• The NMI and watchdog timer interrupts are available because the FMR0 and FMR1 registers are forcibly
reset when either interrupt occurs. Allocate jump addresses for individual interrupt routine to the fixed
vector table. Rewrite operation is aborted when the NMI or watchdog timer interrupt occurs. Execute a
rewrite program again after exiting the interrupt routine.
• The address match interrupt is not available because the CPU references data in the flash memory.
EW1 Mode
• Do not acknowledge any interrupts having vectors in the relocatable vector table or address match interrupt
during auto-program or auto-erase operation.
• Do not use the watchdog timer interrupt.
• The NMI interrupt is available since registers FMR0 and FMR1 are forcibly reset when the interrupt
occurs. Allocate a jump address for individual interrupt routine to the fixed vector table. Rewrite operation
is aborted when the NMI interrupt occurs. Execute a rewrite program again after exiting the interrupt
routine.
22.14.11 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.
22.14.12 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.
22.14.13 DMA transfer
In EW1 mode, make sure that no DMA transfers will occur while the FMR00 bit in the FMR0 register = 0
(during the auto program or auto erase period).
Rev.1.22 Mar 29, 2007 Page 285 of 291
REJ09B0179-0122