H O S T I N T E R F A C E
Data Device Corporation
DS-BU-67301B-G
1/14
77
Figure 37. Synchronous, Non-Multiplexed Address, 32-bit - Sequential Burst Memory
Read Transfer Timing
Figure 37 Notes:
1. A one-clock-cycle wide pulse of nDATA_STRB (low) when nSELECT is
asserted (low) initiates the sequential burst transfer. nSELECT must be
asserted low through the full burst cycle.
2. The nDATA_RDY output is initially asserted low on the same clock cycle when
the
Total-AceXtreme®
drives the first valid data word on the data bus.
CPU_nLAST must be asserted high until the last word is to be read. On the
rising clock edge following CPU_nLAST asserting low, the last word is
removed (tri-stated) from the data bus, and nDATA_RDY is de-asserted
(high). At this time (or later) nSELECT must be de-asserted high, completing
the burst read transfer.
3. The CPU_WORD_EN[1:0] inputs are used to specify which 16-bit data
memory word(s) are valid for this transfer. If either or both these bits is ‘0’,
then the corresponding 16-bit word(s) will return a value of ‘0000’. These
inputs should be tied high if unused.
4. Unless the
Total-AceXtreme
command FIFO is full, CPU_nSTOP is not
asserted, and will remain high.
HOST_CLK
nDATA_RDY
CPU_DATA
CPU_WORD_EN[1:0]
RD_nWR
MEM_nREG
CPU_ADDR
nDATA_STRB
nSELECT
CPU_nLAST
CPU_nSTOP
tAS
tLS
tCLK
tDD
tRDD
Data
Data
Data
Data
Data
Data
Data
Data
tRDD
tCS
tDH
Address
tAH
tCH
tAH
tAH
tAS
tAS
tAS
tSS
tSH
tLH
tLS
tLH
tSHC
tAH
tWait