H8SSLASH2214 datasheet(210/936 Pages) RENESAS

Il numero della parte	H8S/2214

Spiegazioni elettronici	16-Bit Single-Chip Microcomputer H8S Family/H8S/2200 Series

PDF	936 Pages

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Produttore elettronici	RENESAS [Renesas Technology Corp]

Homepage	http://www.renesas.com

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Section 6 Bus Controller

Rev.4.00 Sep. 18, 2008 Page 150 of 872

REJ09B0189-0400

6.4.5

Wait Control

When accessing external space, the H8S/2214 Group can extend the bus cycle by inserting one or

more wait states (Tw). There are two ways of inserting wait states: (1) program wait insertion and

(2) pin wait insertion using the

WAIT pin.

(1) Program Wait Insertion

From 0 to 3 wait states can be inserted automatically between the T

2 state and T3 state on an

individual area basis in 3-state access space, according to the settings of WCRH and WCRL.

(2) Pin Wait Insertion

Setting the WAITE bit in BCRH to 1 enables wait insertion by means of the

WAIT pin. When

external space is accessed in this state, program wait insertion is first carried out according to the

settings in WCRH and WCRL. Then, if the

WAIT pin is low at the falling edge of φ in the last T

or T

W state, a TW state is inserted. If the WAIT pin is held low, TW states are inserted until it goes

high.

This is useful when inserting four or more T

W states, or when changing the number of TW states for

different external devices.

The WAITE bit setting applies to all areas.

H8S/2214 Scheda tecnica(PDF) 210 Page - Renesas Technology Corp