A.2 Off-chip signals

Table A-3 Off-chip signals

Signal

Type

Source/

Function

destination

CLKOut

Output

Pad

SDRAM clock

CLKIn

Input

Pad

External SDRAM clock

CKEOut[3:0]

Output

Pad

SDRAM clock enables

nCSOut[3:0]

Output

Pad

SDRAM chip selects

AddrOut[14:0]

Output

Pad/

Address output for SDRAMs

multiplexor

nRASOut

Output

Pad

Row address strobe

nCASOut

Output

Pad

Column address strobe

nWEOut

Output

Pad

Write enable

DataIn[31:0]

Input

Pad/

Read data from the SDRAMs

multiplexor

DataOut[31:0]

Output

Pad/

Data output to SDRAMs

multiplexor

DQMOut[3:0]

Output

Pad

Data mask output to SDRAMs

DataEn

Output

Pad/

Data enable for write transfers

multiplexor

ExtBusReq

Output

Pad arbiter

External address/data bus request

ExtBusGnt

Input

Pad arbiter

External address/data bus grant

ExtCtlReq

Output

Pad arbiter

External control bus request

ExtCtlGnt

Input

Pad arbiter

External control bus grant

ARM DDI 0159D

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A-5