DDC Total-AceXtreme BU-67301B, Руководство по конструкции

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H O S T I N T E R F A C E
Data Device Corporation DS-BU-67301B-G
www.ddc-web.com 1/14
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The operation of the nDATA_RDY signal for single-word Synchronous memory
and register accesses is summarized in Table 4 and described in the paragraphs
that follow.
Table 4. Summary of the Operation of the nDATA_RDY Output Signal for
Synchronous Single-Word Memory and Register Accesses
Transfer Type
Operation of nDATA_RDY
for Memory Access
Operation of nDATA_RDY
for Register Access
32-bit Read
Asserts low until host clock
following nSELECT going high
Asserts low for single clock cycle
32-bit Write Asserts low for single clock cycle Asserts low for single clock cycle
16-bit Read: First Word
Asserts low until host clock
following nSELECT going high
Asserts low for single clock cycle
16-bit Read: Second Word
Asserts low until host clock
following nSELECT going high
Asserts low for single clock cycle
16-bit Write: First Word Asserts low for single clock cycle
Asserts low until host clock
following nSELECT going high.
16-bit Write: Second Word Asserts low for single clock cycle Asserts low for single clock cycle
For 32-bit Synchronous single-word memory read accesses, nDATA_RDY
asserts low when the
Total-AceXtreme® drives valid data to be read on
CPU_DATA(31:0), and de-asserts high on the HOST_CLK rising edge after
nSELECT is sampled high.
For Synchronous 32-bit single-word memory or register write accesses,
nDATA_RDY asserts low for a single host clock cycle when the data from
CPU_DATA(31:0) has been internally latched.
For Synchronous single-word register read accesses, nDATA_RDY asserts low
for a single host clock cycle beginning when the
Total-AceXtreme® drives valid
data to be read on CPU_DATA(31:0) for a 32-bit transfer, or CPU_DATA(15:0)
for each of the two 16-bit transfers.
For each of the two transfers for 16-bit Synchronous single-word memory read
accesses, nDATA_RDY asserts low starting when the
Total-AceXtreme® drives
valid data to be read on CPU_DATA(15:0) and de-asserts high on the
HOST_CLK rising edge after nSELECT is sampled high.
For each of the two transfers for 16-bit Synchronous single-word memory write
accesses, nDATA_RDY asserts low for a single host clock cycle when the
Total-
AceXtreme® internally latches the data transferred over CPU_DATA(15:0).