Altera Avalon Tri-State Conduit Components - Manual (Page 14)

3–2 Chapter 3: Tri-State Conduit Pin Sharer
Parameters
Avalon Tri-State Conduit Components User Guide May 2011 Altera Corporation
Preliminary
Parameters
The parameter editor for the Tri-State Conduit Pin Sharer allows you to specify a
single parameter, the Number of Interfaces. This parameter specifies the number of
controllers that connect to the Tri-State Conduit Pin Sharer.
Complete the following steps to specify shared pins among connected controllers:
1. Add the Tri-State Conduit Pin Sharer to your Qsys design, specifying the number
of interfaces that connect to it.
2. In the Qsys Connections column, connect the tri-state conduit controllers to the
Tri-State Conduit Pin Sharer.
3. The Tri-State Conduit Pin Sharer parameter editor has a table with the following
columns: Interface, Signal Role, Signal Type, Signal Width, and Shared Signal
Name
. To share a signal, type values in the Interface, Signal Role, and Shared
Signal Name columns for all controllers that share that signal.
4. You can use the Update Interface Table button to automatically populate these
values. Figure 3–2 shows that the CFI_Flash memory and IDT_SRAM memory
share the address signal.
Signal Behavior During Reset
At power-on reset, the enables for all bidirectional and tri-state output signals are
disabled.
Figure 3–3 shows the logic that controls these signals.
Figure 3–2. Specifying Shared Signals Using the Tri-State Conduit Pin Sharer
Figure 3–3. Control of Bidirectional and Tri-State Output Signals
D Q
clock
data_out
data_in
data_outen
reset
D Q
clock
write_out
reset