
71
3.1 Resets
r External reset
An external reset is generated if the external reset terminal (RST terminal) is set to the "L" level.
The "L" level must be input at least for 16 machine cycles (16/
φ). While the machine clock is
used, no oscillation stabilization wait interval is placed even if a reset occurs due to the "L" level
input to the external reset pin.
Reference:
If this pin is asserted while an instruction is executed via the external reset pin (while a
transfer instruction such as MOV is executed), the reset input becomes valid after the
instruction being executed is completed.
For a string-processing instruction (such as MOVS), however, the reset input may become
valid before the transfer due to the specified counter value is completed.
If the external reset pin is asserted, the port pin enters the reset status regardless of the
instruction execution cycle (asynchronous operation if asserted).
r Software reset
A software reset is a reset for three machine cycles (3/
φ) generated by writing "0" to the internal
reset signal generation bit (RST) of the low power consumption mode control register (LPMCR).
The oscillation stabilization wait interval is not required for software resets.
r Watchdog timer reset
A watchdog timer reset is generated unless "0" is written to the watchdog timer control bit
(WTE) of the watchdog timer control register (WDTC) within the time specified in the interval
time setting bits (WT1, WT0) of the WDTC after the watchdog timer is activated.
r Power-on reset
A power-on reset is generated when the power is turned on. The oscillation stabilization wait
interval for the MB90V560 and MB90F562/B is fixed at 218/HCLK (about 65.54 ms if the source
oscillation is 4 MHz). The oscillation stabilization wait interval for the MB90561/A, MB90562/A,
MB90F568, MB90567, and MB90568 is fixed at 217/HCLK (about 32.77 ms if the source
oscillation is 4 MHz). A reset occurs after the oscillation stabilization wait interval has elapsed.
Information: Definition of clocks
HCLK: Oscillation clock frequency (Clock supplied from the oscillation pin)
MCLK: Main clock frequency (Clock obtained by dividing the source oscillation by two)
φ : Machine clock (CPU operating clock)
1/
φ: Machine cycle (CPU operating clock cycle)
See Section
4.1 "Clocks" for details about clocks.