Figure 2. MPC574xR Clock calculator setup
Clock sources (e.g. oscillators and PLLs) propagate to the various clock domains from which the MCU modules take their clocks.
Most cells representing clock domain frequencies are not to be modified manually. The user is meant to enter frequencies to the
few select clock sources and all clock domain frequencies derive from these sources. Several clock domain inputs
are
meant to
be modified manually as they represent external clocks that are driven into a pin. There are also input cells that set muxes and
clock dividers. All cells that take entries have blue borders instead of black, as shown in the figure below.
Figure 3. Input cells vs. Output cells
There are limits to what frequencies can be entered to the input frequency cells. Values that are out of range will be rejected and
the user will receive an error message. Invalid clock domain frequencies that arise from valid input values and legal, but improper,
dividers will be shaded in red, as will be explained in greater depth later in this application note.
Frequency values are linked across tabs, so
PER_CLK
in the Tree tab will always be the same as
PER_CLK
in the
Peripheral
Domains
tab. Hyperlinks are provided to duplicate domain names to link back to their points of origin. For example,
PER_CLK
originates in
Tree
. So clicking the
PER_CLK
textbox in
Peripheral Domains
will take the user to
PER_CLK
in Tree. Textboxes that
are links, when hovered over, will cause the mouse cursor to turn into a hand icon and a pop-up to appear, showing the address
of the destination, as shown in the following figure.
NXP Semiconductors
Clock calculator design
MPC574xR Clock Calculator Guide, Rev. 5, October 2018
Application Note
2 / 28
