CY7C68053
Document # 001-06120 Rev *F Page 35 of 39
9.13.3 Sequence Diagram of a Single and Burst Asynchronous Read
Figure 9-16 illustrates the timing relationship of the SLAVE
FIFO signals during an asynchronous FIFO read. It shows a
single read followed by a burst read.
• At t = 0, the FIFO address is stable and the SLCS signal is
asserted.
At t = 1, SLOE is asserted. This results in the data bus being
driven. The data that is driven on to the bus is previous data;
it is data that was in the FIFO from a prior read cycle.
• At t = 2, SLRD is asserted. The SLRD must meet the min-
imum active pulse of tRDpwl and minimum de-active pulse
width of tRDpwh. If SLCS is used then, SLCS must be as-
serted with SLRD or before SLRD is asserted (for example,
the SLCS and SLRD signals must both be asserted to start
a valid read condition).
The data that is driven, after asserting SLRD, is the updated
data from the FIFO. This data is valid after a propagation
delay of tXFD from the activating edge of SLRD. In Figure 9-
16, data N is the first valid data read from the FIFO. For data
to appear on the data bus during the read cycle (for example,
SLRD is asserted), SLOE MUST be in an asserted state.
SLRD and SLOE can also be tied together.
The same sequence of events is also shown for a burst read
marked with T = 0 through 5. Note In burst read mode, during
SLOE assertion, the data bus is in a driven state and outputs
the previous data. Once SLRD is asserted, the data from the
FIFO is driven on the data bus (SLOE must also be asserted)
and then the FIFO pointer is incremented.
SLRD
FLAGS
SLOE
DATA
Figure 9-16. Slave FIFO Asynchronous Read Sequence and Timing Diagram[17]
tRDpwh
tRDpwl
tOEon
tXFD
tXFLG
N
Data (X)
tXFD
N+1
tXFD
tOEoff
N+3
N+2
tOEoff
tXFLG
tSFA tFAH
FIFOADR
SLCS
Driven
tXFD
tOEon
tRDpwh
tRDpwl tRDpwh
tRDpwl tRDpwh
tRDpwl
tFAH tSFA
N
t=0 T=0
T=1 T=7
T=2 T=3 T=4 T=5 T=6
t=1
t=2 t=3
t=4
NN
SLOE SLRD
FIFO POINTER
N+3
FIFO DATA BUSNot Driven Driven: X N Not Driven
SLOE
N
N+2
N+3
Figure 9-17. Slave FIFO Asynchronous Read Sequence of Events Diagram
SLRD
N
N+1
SLRD
N+1
SLRD
N+1
N+2
SLRD
N+2
SLRD
N+2
N+1
SLOE
Not Driven
SLOE
N
N+1
N+1
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