TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual
13-59
V2.0, 2007-07
EBU, V2.0
Figure 13-20 External Wait Insertion (Synchronous Mode)
shows an example of the extension of the Command Phase through the
WAIT input in asynchronous mode:
•
At LMBCLK edge 1 (at the end of the Address Phase), the EBU samples the WAIT
input as low and starts the first cycle of the Command Phase (CPi1 - internally
programmed).
•
At LMBCLK edge 2, the EBU samples the WAIT input as low and starts the second
cycle of the Command Phase (CPi2 - internally programmed).
•
At LMBCLK edge 3, the EBU samples the WAIT input as high and starts an additional
Command Phase cycle (CPe3 - externally generated) as a result of the WAIT input
sampled as low at LMBCLK edge 1.
•
At LMBCLK edge 4, the EBU starts an additional Command Phase cycle (CPe4 -
externally generated) as a result of the WAIT input sampled as low at LMBCLK
edge 2.
LMBCLK
A[23:0]
Address
MCT05731
AP
CPi1
CPi2
CPe3
RP1
CSx
RD
Data in
D[31:0]
WAIT
Read Access with Synchronous WAIT
1
2
3
4
(active low)
In the example above, the Command Delay phase is internally
programmed to zero LMBCLK cycles (no Command Delay phase).
The Command Phase is internally programmed to one LMBCLK
cycle. All other phases are programmed for one LMBCLK cycle.
Note: