External Core Complex Interfaces
e200z3 Power Architecture Core Reference Manual, Rev. 2
7-38
Freescale Semiconductor
Figure 7-9. Multiple-Cycle Reads with Wait-State, Single-Cycle Writes, Full Pipelining
The first read request (addr
x
) is taken at the end of cycle C1 because the bus is idle. The second read request
(addr
y
) is not taken at the end of cycle C2 because no ready response is signaled and only one access can
be outstanding (addr
x
). It is taken at the end of C3 once the first read request has signaled a ready/OKAY
response.
The first write request (addr
z
) is not taken during C4 because a ready response is not asserted during C4
for the second read access (addr
y
). During C5, the request for a write to addr
z
is taken because the second
access is terminating.
Data for the addr
z
write cycle is driven in C6, the cycle after the access is taken. During C6, the addr
z
write
access is terminated and the addr
w
write request is taken.
During C7, data for the addr
w
write access is driven, and a ready/OKAY response is asserted to complete
the write cycle to addr
w
.
shows another sequence of read and write cycles. In this example, reads incur a single wait
state.
nonseq
nonseq
nonseq
nonseq
idle
addr x
addr y
addr z
addr w
single
single
single
single
data x
data y
data z
data w
okay
okay
okay
okay
okay
okay
okay
1
2
3
4
5
6
7
8
m_clk
p_htrans
p_addr,p_hprot
p_hsize
,
p_hbstrb
, etc
p_hburst
p_hunalign
p_hwrite
p_hrdata
p_hwdata
p_hready
p_hresp
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