CHAPTER 5 INITIALIZATION INTERFACE
User’s Manual U14272EJ3V0UM
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5.1.3 Deadman’s Switch reset
After the Deadman’s Switch unit is enabled, if the Deadman’s Switch is not cleared within the specified time
period, the V
R
4181 immediately enters to reset status. Setting and clearing of the Deadman’s Switch is performed by
software.
A Deadman’s Switch reset initializes the entire internal state except for the RTC timer, the GIU, and the PMU.
Since the DRAM is not switched to self-refresh mode, the contents of DRAM after a Deadman’s Switch reset are not
at all guaranteed.
After a reset, the processor becomes the system bus master, which executes a Cold Reset exception sequence
and begins to access the reset vectors in the ROM space. Since only part of the internal status is reset when a reset
occurs in the V
R
4181, the processor should be completely initialized by software (see 5.4 Notes on Initialization).
Figure 5-3. Deadman’s Switch Reset
L
16MasterClock
Note
Reset# (Internal)
ColdReset# (Internal)
MPOW ER (Output)
POWER (Input)
RSTSW# (Input)
RTC (Internal,
32.768 kHz)
16 ms
PLL (Internal)
H
Stable oscillation
Stable oscillation
Undefined
Stable oscillation
H
Note MasterClock is the basic clock used in the CPU core. Its frequency is one forth of TClock frequency.