NXP Semiconductors MPC5605BK, Reference Manual

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Chapter 1 Preface
MPC5606BK Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 29
oscillator is not started automatically after reset. The oscillator module is described in Section 6.3, Fast
external crystal oscillator (FXOSC) digital interface, along with the internal clock architecture and the
other oscillator sources on chip.
1.7.2 Input/output pins
The majority of the pins on the MCU are input/output pins, which may either operate as general purpose
pins or be connected to a particular on-chip module. The arrangement allows a function to be available on
several pins. The system designer should allocate the function for the pin before connecting to external
hardware. The software should then choose the correct function to match the hardware. The pad
characteristics can vary depending on the functions on the pad.
Chapter 4, Signal description, describes
each pad type (for example, S, M, or J). Two pads may be able to carry the same function but have different
pad types. The electrical specification of the pads is described in the data sheet dependent on the function
enabled and the pad type.
There are three modules that configure the various functions available:
• System Integration Unit Lite (SIUL)
• Wakeup Unit (WKPU)
• 32 KHz oscillator (SXOSC)
The SIUL configures the digital pin functions. Each pin has a register (PCR) in the module that allows
selection of the output functions that is connected to the pin. The available settings for the PCR are
described in
Section 4.2, Pin muxing. Inputs are selected using the PSMI registers; these are described in
Chapter 20, System Integration Unit Lite (SIUL) . (PSMI registers connect a module to one of several pins,
whereas the PCR registers connect a pin to one of several modules).
The WKPU provides the ability to cause interrupts and wake the MCU from low power modes, and
operates independently from the SIUL.
In addition to digital I/O functions, the SXOSC is a “special function” that provides a slow external crystal.
The SXOSC is enabled independently from the digital I/O, which means that the digital function on the
pin must be disabled when the SXOSC is active.
The ADC functions are enabled using the PCRs.
1.7.3 Software design
Certain modules provide system integration functions, and other modules (such as timers) provide specific
functions.
From reset, the modules involved in configuring the system for application software are:
• Boot Assist Module (BAM) — determines the selected boot source
• Reset Generation Module (MC_RGM) — determines the behavior of the MCU when various reset
sources are triggered and reports the source of the reset
• Mode Entry Module (MC_ME) — controls the operating mode the MCU is in and configures the
peripherals, clocks, and power supplies for each of the modes
• Power Control Unit (MC_PCU) — determines which power domains are active