User Guide
4
1 – Peripherals
Enabling/Disabling MSS Sub-blocks
Certain peripherals in the MSS can be enabled or disabled. This is indicated graphically by the checkbox
in the lower right corner of the instance item in the Canvas, as shown in
Figure 1-1.
Click the checkbox icon to enable or disable the sub-block.
You can also use the shortcut (right-click) menu to enable or disable a block. To do so, right-click the
block and choose Disable.
Why would I disable or enable a sub-block?
• Disabling a sub-block causes it to be held in reset when the Microcontroller Subsystem is
powered up. This minimizes any activity that may occur in the sub-block after startup and reduces
power consumption.
• In the case of digital peripherals such as USB, Ethernet MAC, MMUART, I2C, SPI, CAN and
GPIO it is important to disable peripherals that are not used by the application as they share chip
level general purpose I/O resources with other peripherals as well as the FPGA fabric. Leaving a
peripheral enabled may prevent you from using other peripherals and lower the total number of
general purpose I/Os available to the FPGA fabric.
Configuring Sub-blocks
MSS peripherals that have configurable options have a wrench icon in the lower right corner of the
instance item in the Canvas, as shown in
Figure 1-2.
Figure 1-1 • Enabled and Disabled Blocks