H83069RF datasheet(96/1003 Pages) RENESAS

96 / 1003 page

Rev. 5.0, 09/04, page 74 of 978

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

chip 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 chip can also be reset by overflow of the watchdog timer. For details see section 12,

Watchdog Timer.

4.2.2

Reset Sequence

The chip enters the reset state when the

RES pin goes low.

To ensure that the chip is reset, hold the

RES pin low for at least 20 ms at power-up. To reset the

chip during operation, hold the

RES pin low for at least 20 system clock (φ) 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 chip 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 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.

Note : The normal mode cannot be selected in the H8/3069R

Figure 4.2 shows the reset sequence in modes 1 and 3. Figure 4.3 shows the reset sequence in

modes 2 and 4.

• After power is turned on, hold the RES pin low and the STBY pin high.

H83069RF Datasheet(PDF) 96 Page - Renesas Technology Corp