Table 3.5 Reset Source; Resets - Fujitsu F2MC-8L MB89620 Series Hardware Manual

5
3.

Resets

The MB89620 series supports the following four types of reset source:
• External reset
• Software reset
• Watchdog reset
• Power-on reset (optional)
The pin states during a reset or during reset operation depend on the operating mode.
n Reset Source

Table 3.5 Reset Source

Reset source
External reset
Software reset
Watchdog reset
Power-on reset
External reset
l
Inputting an "L" level to the external reset pin (RST) generates an external reset. Returning the
reset pin to the "H" level wakes up the CPU from the external reset.
When power is turned on to products with power-on reset or for external resets in stop mode,
the reset operation is performed after the oscillation stabilization delay time has passed and the
CPU wakes up from the external reset. External resets on products without power-on reset do
not wait for the oscillation stabilization delay time.
The external reset pin can also function as a reset output pin (optional).
Software reset
l
Writing "0" to the software reset bit in the standby control register (STBC: RST) generates a four-
instruction cycle reset. The software reset does not wait for the oscillation stabilization delay
time.
l Watchdog reset
The watchdog reset generates a four-instruction cycle reset if data is not written to the watchdog
timer control register (WDTC) within a fixed time after the watchdog timer starts. The watchdog
reset does not wait for the oscillation stabilization delay time.
l Power-on reset
Products can be set to with or without power-on reset (optional). On products with power-on
reset, turning on the power generates a reset. The reset operation is performed after the
oscillation stabilization delay time has passed.
On products with power-on reset, an external reset circuit is required to generate a reset when
the power is turned on.
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CHAPTER 3 CPU
Set the external reset pin to the "L" level.
Write "0" to the software reset bit in the standby control register (STBC: RST).
Watchdog timer overflow
Power is turned on (only on products with a power-on reset).
Reset conditions
MB89620 series