M3850 RENESAS [Renesas Technology Corp], M3850 Datasheet - Page 45

• Manufacturer Part Number: M3850
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: RENESAS [Renesas Technology Corp]

3850 Group (Spec.A)
Precautions on CPU Rewrite Mode
Described below are the precautions to be observed when rewriting
the flash memory in CPU rewrite mode.
(1) Operation speed
(2) Instructions inhibited against use
(3) Interrupts inhibited against use
(4) Watchdog timer
(5) Reset
Rev.2.10
REJ03B0093-0210
During CPU rewrite mode, set the internal clock frequency 6.25
MHz or less using the main clock division ratio selection bits (bit
6, 7 at 003B
The instructions which refer to the internal data of the flash
memory cannot be used during CPU rewrite mode .
The interrupts cannot be used during CPU rewrite mode be-
cause they refer to the internal data of the flash memory.
In case of the watchdog timer has been running already, the in-
ternal reset generated by watchdog timer underflow does not
happen, because of watchdog timer is always clearing during
program or erase operation.
Reset is always valid. In case of CNV
leased, boot mode is active. So the program starts from the ad-
dress contained in address FFFC
area.
2005.11.14
16
).
page 45 of 86
16
and FFFD
SS
= H when reset is re-
16
in boot ROM