Cirrus-logic EP73xx Bedienungsanleitung PDF herunterladen (Seite 85)

EP7309/11/12 User’s Manual - DS508UM4 8-1

Chapter 8

8SRAM/Expansion Bus Controller

Introduction

The SRAM/Expansion bus controller allows for control and access to

internal/external SRAM memory as well as external peripherals that require

read/write access to the EP73xx memory bus. The following description will

encompass both situations and detail the programming and configuration of each of

bus.

Features

• Six programmable chip selects CS0-CS5

• CS6 (Internal SRAM) chip select pre-programmed

•

CS7 (Internal Boot ROM) chip select pre-programmed

• Wait states programmable from 0-8

• Bus width programmable from 8-32 bits wide

SRAM / Expansion Bus Register List

Programming Example

;*****************************************************************************

; Expansion bus settings in this example are based on the bootmode pins PE1 and

;

PE0 at nPOR (power-on-reset) as (0,0) with the PLL clock set at 74 MHz

;

nCS0 = 32-bit, 3 wait states

;

nCS1 = 32-bit, 2 wait states

;

nCS2 = 16-bit, 8 wait states

;

nCS3 = 32-bit, 1 wait state

;

nCS4 =8-bit,1waitstate

;

nCS5 = 32-bit, 8 wait states

;*****************************************************************************

Table 8-1: SRAM / Expansion Bus Registers

Address Name Type Size Description Page

0x8000.0180 MEMCFG1 R/W 32 Memory Config. Reg 1 page 8-3

0x8000.01C0 MEMCFG2 R/W 32 Memory Config. Reg 2 page 8-5

1 2 ... 80 81 82 83 84 85 86 87 88 89 90 ... 157 158

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