TMPR4938 datasheet(131/716 Pages) TOSHIBA

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Chapter 7 External Bus Controller

7-21

7.3.9.2

Usage Considerations

To use ISA and ATA modules in READY, their ICCHRDY or IORDY pin should be connected

to the ACK*/READY pin of the TX4938.

The SHWT option allows users to adjust the setup and hold timing of IOR* and IOW* relative

to ADDR.

When the READY mode and SHWT option are used, the internal bus burst accesses are

prohibited.

Although the ISA and ATA signals are 5-volt signals, the TX4938 is not 5-volt-tolerant. For

voltage-level conversion, bus switches such as BUSSW and LCX245 must be inserted between

ISA busses according to the modules used.

7.3.9.3

Usage Examples

(1) 8-bit ISA module

Following is a programming example to use an 8-bit ISA module:

•

ISA mode (EBCCRn.ISA=01)

•

8-bit bus (EBCCRn.BSZ=11)

•

READY mode (EBCCRn.RDY=1, EBCCRn.PM=00)

•

Channel enable (EBCCRn.ME=1)

•

ISA select (PCFG.ISA_SEL=1)

Program the number of wait cycles, the SHWT option and the bus speed according to the ISA

module used. Figure 7.3.16 shows an example of connecting an 8-bit ISA module to the TX4938.

Figure 7.3.16 An Example of Connecting an 8-Bit ISA Module

TX4938

ADDR[15:0]

DATA[7:0]

IOR*

IOW*

ACK*/READY

ISA-Module

SA[15:0]

SD[7:0]

IOR*

IOW*

IOCHRDY

AEN

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