CL-PS7110 View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CL-PS7110

Low-Power System-on-a-Chip

Cirrus Logic 

CL-PS7110

Low-Power System-on-a-Chip

Figure 1-4 shows the usage of such memory segments.

× 16

FLASH

× 16

ROM

CL-PS7110

D[0:31]

A[0:27]

NMOE

NMWE

NCS0

NCS1

× 16

FLASH

× 16

ROM

CS6

CS7

EXTERNAL MEMORY

MAPPED EXPANSION

BUFFERS

ADDITIONAL I/O

BUFFERS

AND

LATCHES

NCS2

NCS3

Figure 1-4. Memory Segment Usage

The width of each the ROM/expansion bank is set in its Memory Configuration Register 1 (see

Section 3.2.13). This register is cleared to zero by a power-on reset. The CL-PS7110 boots from

ROM/expansion bank 0. To allow for booting from 8- or 32-bit memory devices, the state of port E bit 0 is

sampled during power-on reset and stored into the BOOT8BIT Mode register. If this bit is low, all zeros in

the width field of a memory configuration register indicates a 32-bit-wide bank and all ones a 8-bit device.

If this bit is high, the decoding of the bus width field is inverted, so all zeros indicates a 8-bit device.This

way, a pull-up or pull-down on port E bit 0 indicates the size of the boot device. For consistency, the

BOOT8BIT Mode has the same effect on all ROM/expansion banks.

The PCMCIA mode is a special case. If the width field of the Memory Configuration Register 1 is set to

PCMCIA mode, the upper address bits are decoded to determine the bus width and type of access. The

PCMCIA address bits A0 to A25 are driven by CL-PS7110 address bits A0 to A25. CL-PS7110 address

bits A26 and A27 are decoded to specify the type and width of the access. If both are zeros, it is an access

to the 8-bit-wide attribute memory. If only A26 is a one, it is an access to the 16-bit-wide common memory.

If only A27 is a one, it is an access to a 8-bit-wide I/O register. If both are ones, it is an access to a 16-bit-

wide I/O register.

The ARM710A core only supports byte or word accesses. Normally, word accesses are converted to mul-

tiple bus cycles that match the width of the ROM/expansion bank. Word accesses to PCMCIA 16-bit-wide

18

FUNCTIONAL DESCRIPTION

May 1997

DATA BOOK v1.5

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