7643 datasheet(297/424 Pages) RENESAS

tên linh kiện	7643

Giải thích chi tiết về linh kiện	8-BIT SINGLE-CHIP MICROCOMPUTER

PDF	424 Pages

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nhà sản xuất	RENESAS [Renesas Technology Corp]

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297 / 424 page

Rev.2.00

Aug 28, 2006

page 176 of 202

7643 Group

REJ09B0133-0200

APPLICATION

2.8 External device connection

2.8.3 Functional description

This MCU starts its operation in the single-chip mode just after reset.

(1) Memory expansion mode

This mode is selected by setting “01” to the processor mode bits (b1, b0 of CPMA) in software

with CNVSS connected to VSS.

In this mode, the ports function as follows:

Ports P0 and P1 as address buses (AB0 to AB15)

Port P2 as data buses (DB0 to DB7)

______

Ports P33 to P37 as DMAOUT,

φOUT, SYNCOUT, WR, RD pins respectively.

This mode enables external memory expansion while maintaining the validity of the internal ROM.

(2) Microprocessor mode

This mode is selected by resetting the MCU with CNVSS connected to VCC, or by setting “10” to

the processor mode bits (b1, b0 of CPMA) in software with CNVSS connected to VSS. The function

is the same as that of memory expansion mode.

In the microprocessor mode, the internal ROM is no longer valid and an external memory must

be used.

Do not set this mode in the flash memory version.

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