HD6413002 Datasheet, PDF (82/700 Pages) Renesas Technology Corp – High-performance single-chip microcontroller

4.2 Reset
4.2.1 Overview
A reset is the highest-priority exception. When the RES pin goes low, all processing halts and the
H8/3002 enters the reset state. A reset initializes the internal state of the CPU and the registers of
the on-chip supporting modules. Reset exception handling begins when the RES pin changes from
low to high.
The H8/3002 can also be reset by overflow of the watchdog timer. For details see section 12,
Watchdog Timer.
4.2.2 Reset Sequence
The H8/3002 enters the reset state when the RES pin goes low.
To ensure that the H8/3002 is reset, hold the RES pin low for at least 20 ms at power-up. To reset
the H8/3002 during operation, hold the RES pin low for at least 10 system clock (ø) cycles. See
appendix D.2, Pin States at Reset, for the states of the pins in the reset state.
When the RES pin goes high after being held low for the necessary time, the H8/3002 starts reset
exception handling as follows.
• The internal state of the CPU and the registers of the on-chip supporting modules are
initialized, and the I bit is set to 1 in CCR.
• The contents of the reset vector address (H'0000 to H'0003) are read, and program execution
starts from the address indicated in the vector address.
Figure 4-2 shows the reset sequence in modes 1 and 3. Figure 4-3 shows the reset sequence in
modes 2 and 4.
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