EMC326SP16AJ datasheet(21/64 Pages) EMLSI

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EMC326SP16AJ

2Mx16 CellularRAM

Preliminary

Software Access

Software access of the registers uses a sequence of asynchronous READ and asynchronous WRITE operations. The contents of the

configuration registers can be modified and all registers can be read using the software sequence. The configuration registers are

loaded using a four-step sequence consisting of two asynchronous READ operations followed by two asynchronous WRITE

operations.(See Figure 14.) The read sequence is virtually identical except that an asynchronous READ is performed during the fourth

operation. (See Figure 15.) The address used during all READ and WRITE operations is the highest address of the CellularRAM

device being accessed (1FFFFFh); the contents of this address are not changed by using this sequence. The data value presented

during the third operation (WRITE) in the sequence defines whether the BCR, RCR, or the DIDR is to be accessed. If the data is

0000h, the sequence will access the RCR; if the data is 0001h, the sequence will access the BCR; if the data is 0002h, the sequence

will access the DIDR. During the fourth operation, DQ[15:0] transfer data in to or out of bits 15:0 of the registers. The use of the

software sequence does not affect the ability to perform the standard (CRE-controlled) method of loading the configuration registers.

However, the software nature of this access mechanism eliminates the need for CRE. If the software mechanism is used, CRE can

simply be tied to Vss. The port line often used for CRE control purposes is no longer required.

Figure 14: Load Configuration Register

Figure 15: Read Configuration Register

Address

CE#

OE#

WE#

LB#/UB#

DATA

ADDRESS

Max

ADDRESS

Max

ADDRESS

Max

ADDRESS

Max

XXXXh

RCR : 0000h

BCR : 0001h

CR Value In

Don’t Care

READ

WRITE

Address

CE#

OE#

WE#

LB#/UB#

DATA

ADDRESS

Max

ADDRESS

Max

ADDRESS

Max

ADDRESS

Max

XXXXh

RCR : 0000h

BCR : 0001h

CR Value In

Don’t Care

READ

WRITE

READ

DIDR : 0002h

EMC326SP16AJ Datasheet(PDF) 21 Page - Emerging Memory & Logic Solutions Inc

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