Cirrus-logic EP93xx Manual do Utilizador descarregar pdf (Página 497)

100

101

DS785UM1 13-1

Chapter 13

13SDRAM, SyncROM, and SyncFLASH Controller

13.1 Introduction

Note: In the EP9301 and 9302 processors, the common address/data bus is 16-bits wide

and the SDRAM, SyncROM, and SyncFLASH synchronous memory controller

supports 16-bit and 8-bit devices.

Note: In the EP9307, EP9312, and EP9315 processors, the common address/data bus is

programmable to be either 16-bits or 32-bits wide and the SDRAM, SyncROM, and

SyncFLASH synchronous memory controller supports 32-bit , 16-bit, and 8-bit

devices.

The SDRAM controller provides a high speed memory interface to single-data-rate SDRAMs,

Synchronous FLASH, and Synchronous ROMs.

The key features of the SDRAM controller are:

• Raster DMA input port for high-bandwidth display refreshing.

• Up to four synchronous memory banks that can be independently configured

• Special configuration bits for Synchronous ROM operation

• Ability to program Synchronous FLASH devices using write and erase commands

• Data is transferred between the controller and the synchronous memory device in quad-

word bursts.

• Programmable for 16 or 32-bit data bus: EP9307, EP9312, and EP9315 processors only

• SDRAM contents are preserved when a “soft” reset is asserted

• Power saving synchronous memory clock enable

13.2 Booting from SyncROM or SyncFLASH

During power-on reset, if the values on the processor pins shown in Table CAUTION: select

either a Synchronous ROM device or Synchronous FLASH device to be used for booting up

the processor, a short configuration sequence is activated and completed before the

processor is released from power-on reset. By default, Synchronous Memory Bank 3,

controlled by device configuration register SDRAMDevCfg[3:0], is used for booting.

For a Synchronous ROM device, the configuration sequence writes RAS = 0x2 and CAS =

0x5 to the SDRAMDevCfg[3:0] register and writes RAS = 0x2, CAS = 0x5, and either Burst

1 2 ... 492 493 494 495 496 497 498 499 500 501 502 ... 823 824

Comentários a estes Manuais

Sem comentários

Cirrus-logic EP93xx Manual do Utilizador Página 497

Comentários a estes Manuais