38K0 Datasheet, PDF (85/133 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K0 Group
Notes on CPU Rewrite Mode
Take the notes described below when rewriting the flash memory
in CPU rewrite mode.
qOperation speed
During CPU rewrite mode, set the internal clock φ to 1.5 MHz or
less using the system clock division ratio selection bits (bits 6 and
7 of address 003B16).
qInstructions inhibited against use
The instructions which refer to the internal data of the flash
memory cannot be used during CPU rewrite mode .
qInterrupts inhibited against use
The interrupts cannot be used during CPU rewrite mode because
they refer to the internal data of the flash memory.
qWatchdog timer
If the watchdog timer has been already activated, internal reset
due to an underflow will not occur because the watchdog timer is
surely cleared during program or erase.
qReset
Reset is always valid. The MCU is activated using the boot mode
at release of reset in the condition of CNVss = “H”, so that the pro-
gram will begin at the address which is stored in addresses
FFFC16 and FFFD16 of the boot ROM area.
Rev.3.00 Oct 05, 2006 page 85 of 129
REJ03B0192-0300