H8SSLASH2225 datasheet(284/1071 Pages) RENESAS

部件名	H8S/2225

功能描述	16-Bit Single-Chip Microcomputer H8S Family/H8S/2200 Series

PDF	1071 Pages

Scroll/Zoom	100%

制造商	RENESAS [Renesas Technology Corp]

网页	http://www.renesas.com

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284 / 1071 page

Section 7 Bus Controller

Rev. 5.00 Aug 08, 2006 page 198 of 982

REJ09B0054-0500

Figure 7.24 shows the timing for transition to the bus-released state.

CPU

cycle

Address

Minimum

1 state

HWR, LWR

BREQ

BACK

High impedance

CSn

High impedance

Data bus

Address bus

[1]

[2]

[3]

[4]

[5]

[1]

Low level of

BREQ pin is sampled at rise of T2 state.

[2]

BACK pin is driven low at end of CPU read cycle, releasing bus to external bus

master.

[3]

BREQ pin state is still sampled in external bus released state.

[4]

High level of

BREQ pin is sampled.

[5]

BACK pin is driven high, ending bus release cycle.

CPU cycle

External bus released state

Note : n = 7 to 0

Figure 7.24 Bus-Released State Transition Timing

7.9.1

Bus Release Usage Note

When MSTPCR is set to H'FFFFFF and transmitted to sleep mode, the external bus release does

not function. To activate the external bus release in sleep mode, do not set MSTPCR to H'FFFFFF.

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