MB91301 Datasheet, PDF (25/135 Pages) Fuji Electric – 32-Bit Proprietary Microcontroller

MB91301 Series
• I-bus memory
Do not set a stack area or vector table in I-bus memory.
It may cause a hang during EIT processing (including RETI).
Recovery from the hang requires a reset.
Do not perform DMA transfer to I-bus memory.
• Low-power consumption modes
• To enter the standby mode, use the synchronous standby mode (set with the SYNCS bit as bit 8 in the
TBCR, or time-base counter control register) and be sure to use the following sequence:
(LDI #value_of_standby, R0)
(LDI #_STCR, R12)
STB R0, @R12
; Write to standby control register (STCR)
LDUB @R12, R0
; Read STCR for synchronous standby
LDUB @R12, R0
; Read STCR again for dummy read
NOP
; NOP x 5 for timing adjustment
NOP
NOP
NOP
NOP
• If you use the monitor debugger, follow the precautions below:
Do not set a breakpoint within the above array of instructions.
Do not single-step the above array of instructions.
• Prefetch
When accessing a prefetch-enabled little endian area, use word access only (access in 32 bits).
Byte or halfword access results in wrong data read.
• MCLK and SYSCLK
MCLK causes a stop in SLEEP/STOP mode while SYSCLK causes a stop only in STOP mode. Use either
depending on each application.
• Pull-up control
When function pins listed in the AC specifications (such as external bus control pins) have pull-up control,
enabling the pull-up resistor for a pin causes the actual pin load conditions to change. As all AC specifications
for this device were measured under the condition of pull-up resistors disabled, the values are not guaranteed
of AC specifications when pull-up resistors are enabled.
Even if the pull-up resistor is set to enabled for a pin, if the HIZ bit in the standby control register (STCR) specifies
setting output pins to high impedance during stop mode (HIZ = 1) , changing to stop mode (STOP = 1) causes
the pull-up resistor to be disabled.
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