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Creating the Microprocessor Platform in MSB
24
LatticeMico32 Hardware Developer User Guide
Specifying Connections Between Master and Slave
Ports
You interactively make your master/slave connections between these ports in
the Editor view by clicking on those connection line endpoints and then by
saving your project. The .msb file is updated with this information. Figure 9 on
page 25 illustrates the basic structure of this connection between the master
and the slave.
To specify the connections between master and slave ports:
1. Ensure that you have first added your desired components and that they
appear in the Editor view in the MSB perspective.
2. If you want to select a different arbitration scheme, choose
Platform
Tools > Properties
, select the desired arbitration scheme from the pull-
down menu in the Arbitration Scheme box, and click
OK
.
3. In the Editor view’s Connection column, for each listed slave component,
click on the blue-outlined, rounded endpoint to complete the connection to
the CPU's master ports. The rounded endpoint now appears filled in; that
is, it turns solid blue, indicating that the slave is “connected” to the master
port.
Connection points occur at the intersection of the vertical lines down from
the master at the slave horizontal lines and coincide with a desired
connection to master instruction, data ports, or both. You may or may not
wish to connect to both master ports, depending on the necessary input
on a given slave component.
For example, suppose that a CPU's master ports are composed of an
instruction port and a data port. You want to connect the CPU's instruction
port, but not its data port, to a UART's slave port. You would go to the
Connection column in the UART row and click on the outline circle linked
to the instruction port to fill it in, but not on the outlined circle linked to the
data port.
4. Choose
File > Save
or click the
Save
toolbar button.
The connections that you made are saved in the .msb file.
Figure 9 shows an example of the connections that result in the Editor view
when the shared-bus arbitration scheme is used. All master signal connection
lines are represented in black, and all slave connection lines are represented
in blue.
Figure 10 shows an example of the connections that result in the Editor view
when the slave-side fixed and slave-side round-robin arbitration schemes are
used.
In the slave-side fixed arbitration scheme, you can change the priorities of the
master ports, so the Edit Arbitration Priorities command is available on the
Platform Tools menu, as shown in Figure 11. However, in the slave-side
round-robin arbitration scheme, you cannot change the priorities of the master
ports because the arbitration between the master ports occurs in a round-
robin fashion. The Edit Arbitration Priorities command on the Platform Tools
