Memory Controller

Figure 6-27. Expansion Card External Logic for a One-Socket Configuration

Intel® - PXA255 Processor

Socket 0

 

 

MD<15:0>

 

D<15:0>

 

DIR

nOE

RD/nWR

 

 

GPIO<w>

nPCD0

nCD<1>

 

 

GPIO<x>

nPCD1

nCD<2>

 

 

PSKTSEL

 

 

GPIO<y>

PRDY_BSY0

RDY/nBSY

PADDR_EN0

GPIO<z>

 

 

 

MA[25:0]

 

A[25:0]

 

 

nPWE

 

nWE

 

 

nPREG

 

nREG

nPCE<2:1>

 

nCE<2:1>

 

nOE

nPOE

 

 

nIOR

nPIOR

 

 

nIOW

nPIOW

 

 

 

 

5V to 3.3V or 2.5V

nPWAIT

 

nWAIT

 

5V to 3.3V or 2.5V

nIOIS16

 

nIOIS16

Figure 6-28shows the glue logic need for a 2-socket system. RDY/nBSY signals are routed through a buffer to two separate GPIO pins. In the data bus transceiver control logic, nPCE1 controls the enable for the low byte lane and nPCE2 controls the enable for the high byte lane.\

Intel® PXA255 Processor Developer’s Manual

6-67

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Image 249
Intel PXA255 manual Dir