H8SLASH3028F datasheet(168/923 Pages) RENESAS

Nome de Peças	H8/3028F

Descrição Electrónicos	Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

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Fabricante Electrônico	RENESAS [Renesas Technology Corp]

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168 / 923 page

Rev. 2.00, 09/03, page 138 of 890

16-Bit Access Areas: Figure 6.8 illustrates data alignment control for 16-bit access areas. With

16-bit access areas, the upper data bus (D15 to D8) and lower data bus (D7 to D0) are used for

accesses. The amount of data that can be accessed at one time is one byte or one word, and a

longword access is executed as two word accesses.

In byte access, whether the upper or lower data bus is used is determined by whether the address is

even or odd. The upper data bus is used for an even address, and the lower data bus for an odd

address.

D15

D8 D7

Upper data bus

Lower data bus

1st bus cycle

2nd bus cycle

Byte size

Longword size

· Even address

· Odd address

Word size

Byte size

Figure 6.8 Access Sizes and Data Alignment Control (16-Bit Access Area)

6.4.3

Valid Strobes

Table 6.4 shows the data buses used, and the valid strobes, for the access spaces.

In a read, the

RD signal is valid for both the upper and the lower half of the data bus.

In a write, the

HWR signal is valid for the upper half of the data bus, and the LWR signal for the

lower half.

H8/3028F Folha de dados(PDF) 168 Page - Renesas Technology Corp