HD643303x Hitachi, HD643303x Datasheet - Page 82

• Manufacturer Part Number: HD643303x
• Description: Hitachi Microcomputer
• Manufacturer: Hitachi

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
H8/3032 Series 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 H8/3032 Series can also be reset by overflow of the watchdog timer. For details see section
10, Watchdog Timer.
4.2.2 Reset Sequence
The H8/3032 Series enters the reset state when the RES pin goes low.
To ensure that the H8/3032 Series is reset, hold the RES pin low for at least 20 ms at power-up. To
reset the H8/3032 Series 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 H8/3032 Series starts
reset exception handling as follows.
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Figure 4-2 shows the reset sequence in modes 1 and 3. Figure 4-3 shows the reset sequence in
mode 2.
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 in advanced mode, H'0000 to
H'0001 in normal mode) are read, and program execution starts from the address indicated in
the vector address.
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