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CHAPTER 7 INITIALIZATION INTERFACE
This chapter describes the Initialization interface and the processor modes. This includes the reset
signal description and types, and initialization sequence, with signals and timing dependencies, and the
user-selectable processor modes.
7.1 RESET FUNCTION
Five methods of resetting the V
R
4101 processor are supported. Each of these methods is outlined
below.
7.1.1 RTC Reset
When turning on the power, activate the RTCRST* pin. After the power supply voltage has stabilized at
2.5 V or more, wait about 230 ms for the 32-kHz oscillator circuit to start, then deactivate the RTCRST*
pin. The RTC unit will start counting. Next, after the power supply voltage has stabilized to between 3.0
V and 3.6 V, activate the POWER pin. The V
R
4101 will assert the POWERON pin then check the
battery charge level by means of the BATTINH signal. If the battery charge level is sufficient and the
GPIO[9] (BATTLOCK) pin has been asserted, the V
R
4101 will assert the MPOWER pin to start the
external DC/DC converter. After the DC/DC converter has stabilized (after about 350 ms), the V
R
4101
starts PLL oscillation, and all clocks are started (Note, however, that after the start of PLL oscillation,
about 8 ms is required for PLL oscillation to stabilize).
The RTC reset does not save any state information, instead completely initializing the internal states of
the processor. Moreover, the processor does not instigate a DRAM transition to self-refresh mode, so
that the contents of DRAM after an RTC reset will be unpredictable.
After a reset, the processor assumes system bus mastership, then begins access to a reset vector in
the ROM space. Upon a reset, the V
R
4101 initializes only some of the internal states. So, initialize the
processor completely by software.
Figure 7-1. RTC Reset
Reset*
(Internal)
ColdReset*
(Internal)
MPOWER
POWER
RTCRST*
RTC
(Internal
C
32kHz)
Stable
oscillation
Stable
oscillation
8ms
350ms
>230ms
Undefined
Undefined
PLL
(Internal)
16MasterClock
Note
7RTC
>32ms
POWERON
Note
MasterClock is the basic clock used in the CPU core.