H8SX1663 datasheet(347/1158 Pages) RENESAS

部件名	H8SX1663

功能描述	Renesas 32-Bit CISC Microcomputer H8SX Family / H8SX/1600 Series

PDF	1158 Pages

Scroll/Zoom	100%

制造商	RENESAS [Renesas Technology Corp]

网页	http://www.renesas.com

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347 / 1158 page

Section 6 Bus Controller (BSC)

Rev.1.00 Jun. 07, 2006 Page 295 of 1102

REJ09B0294-0100

(3) Read after Write

If an external read occurs after an external write while bit IDLS2 in IDLCR is set to 1, idle cycles

specified by bits IDLCA1 and IDLCA0 are inserted at the start of the read cycle (n = 0 to 7).

Figure 6.92 shows an example of the operation in this case. In this example, bus cycle A is a CPU

write cycle and bus cycle B is a read cycle from the SRAM. In (a), an idle cycle is not inserted,

and a conflict occurs in bus cycle B between the CPU write data and read data from an SRAM

device. In (b), an idle cycle is inserted, and a data conflict is prevented.

Output floating

time is long.

Data conflict

Bus cycle A

Bus cycle B

Address bus

CS (area A)

CS (area B)

LLWR

Data bus

Bus cycle A

Bus cycle B

(a) No idle cycle inserted

(IDLS2 = 0)

(b) Idle cycle inserted

(IDLS2 = 1, IDLCA1 = 0, IDLCA0 = 0)

Figure 6.92 Example of Idle Cycle Operation (Read after Write)

H8SX1663 数据表(PDF) 347 Page - Renesas Technology Corp