W958D6DB Datasheet, PDF (21/57 Pages) Winbond – Low-power features

W958D6DB
256Mb Async./Burst/Sync./A/D MUX
8.4.2 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.
The read sequence is virtually identical except that an asynchronous READ is performed during the fourth operation.
The address used during all READ and WRITE operations is the highest address of the ADMUX PSRAM device being
accessed; 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, 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. During the fourth operation, ADQ[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.
8.4.2.1 Load Configuration Register
CE #
READ
READ
WRITE
WRITE
OE #
WE #
LB #/UB #
ADV#
A [max:16 ]
Address
(MAX)
A/DQ[15 :0 _]
Address
(MAX)
XXXX
Address
(MAX)
Address
(MAX)
XXXX
Address
(MAX)
Address
(MAX)
Address
(MAX)
0ns (min)
Address
(MAX)
CR value
in
RCR:0000h
BCR:0001h
Don’t Care
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Publication Release Date : June 27 ,2013
Revision : A01-003