IS66WVC1M16ALL Datasheet, PDF (20/67 Pages) Integrated Silicon Solution, Inc – Mixed Mode supports asynchronous write and synchronous read operation

IS66WVC1M16ALL
IS67WVC1M16ALL
Software Access Sequence
Software access of the configuration registers uses a sequence of asynchronous READ
and asynchronous WRITE operations. The contents of the configuration registers can be
read or modified 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 11). The read sequence is virtually identical except that an asynchronous READ is
performed during the fourth operation (see Figure 12). The address used during all
READ and WRITE operations is the highest address of the CellularRAM device being
accessed (FFFFFh); 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 or the 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;
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 control 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 the control register enable
(CRE) pin. If the software mechanism is used, the CRE pin can simply be tied to VSS.
The port line often used for CRE control purposes is no longer required.
Figure 11 : Configuration Register Write
Address
DQ0-
DQ15
MAX
ADDRESS
OUTPUT
DATA
CE#
Read
UB#/LB#
WE#
OE#
MAX
ADDRESS
OUTPUT
DATA
Read
MAX
ADDRESS
*Note1
Write
MAX
ADDRESS
CR
VALUE IN
Write
Notes :
1. RCR : 0000h , BCR : 0001h
Rev.A | October 2013
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