Intel 386 Uživatelský manuál stáhnout pdf (Strana 155)

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Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL

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6.6.3 PSRAM Interface

Pseudo SRAM (PSRAM) devices can be easily interfaced (Figure 6-17) to the Intel386 EX pro-

cessor. PSRAM devices have an interface that is similar to SRAM devices (They are also pin-

compatible in many cases). The two major differences between PSRAM and SRAM devices are:

• PSRAM devices require a CE# precharge (inactive) time between access cycles. Since the

Intel386 EX processor does not guarantee a minimum inactive time on it’s CSn# signals,

control logic is required to satisfy the PSRAM device’s CE# precharge time.

• PSRAM devices have a RFSH# input pin. This signal activates an internal refresh cycle.

The REFRESH# output of the Intel386 EX processor can be connected directly to the

PSRAM device’s RFSH# pin.

Figure 6-17. Intel386 EX Processor to PSRAM Interface

Intel386™ EX

Embedded

Processor

OE#



WE#



RFSH#

Note:

Control logic is necessary to satisfy the precharge time for the CE# signal of the

PSRAM. The precharge time is specified by the PSRAM manufacturer.

PSRAM

Address

Data

RD#



WR#



REFRESH#

Control

Logic

CE#

A2854-02

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