External Memory Controller
LH79524/LH79525 User’s Guide
7-12
Version 1.0
In Timing B, three wait states are also illustrated. However, in this case, the three wait
states have been programmed by setting SWAITRDx to 0x2 and SWAITOENx to 0x1. In
this case, nOE does not become asserted at the same time as nCSx. Instead, nOE is
delayed by the number of HCLK periods enumerated by SWAITOENx, which in this case
is one, represented by time ‘D1’. Then, instead of the nOE signal deasserting one
HCLK period later, it is extended two wait states because of the programmed value in
SWAITRDx. The result is the same delay of three HCLK periods, but achieved in a
different way to also delay assertion of nOE.
Figure 7-11. Static Read Transaction with Three Wait States
HCLK
A[23:0]
VALID DATA
VALID ADDRESS
LH79525-110
D[31:0]
nCSx
nOE
nCSx
nOE
NOTES:
With Register Programming:
SWAITOENx = D = 0x1
SWAITRDx = E = 0x2
DATA
LATCHED
D1
E0
E1
E2
E3
E0
E1
E2
C
NOTES:
With Register Programming:
SWAITDENx = D = 0x0
SWAITRDx = E = 0x3
TIMING A
TIMING B