Overview
MPC5606S Microcontroller Reference Manual, Rev. 7
72 Freescale Semiconductor
have different pad types. The electrical specification of the pads is described in the MPC5606S
Microcontroller Data Sheet, dependent on the function enabled and the pad type.
There are four modules that configure the various functions available:
• System Integration Unit Lite (SIUL)
• Wakeup Unit (WKPU)
•LCD
• 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 connected to the pin. The available settings for the PCR are described in
Section , . Inputs are selected using the PSMI registers; these are described in Chapter 37, 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. It operates
independently from the SIUL.
In addition to digital I/O functions there are special functions that provide analog functionality. These are
listed in Section , . The special functions are enabled independently from the digital I/O, which means that
the digital function on the pin must be disabled when the special function is active. The LCD module and
the SXOSC oscillator are enabled in the modules. The ADC functions are enabled using the PCRs.
1.8.3 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 MCU’s operating mode the MCU and configures
the peripherals and clocks and power supplies for each of the modes.
• Power Control Unit (MC_PCU) — determines which power domains (see Section Chapter 40,
Voltage Regulators and Power Supplies) are active.
• Clock Generation Module (MC_CGM) — chooses the clock source for the system and many
peripherals.
After reset, the MCU will automatically select the appropriate reset source and begin to execute code. At
this point the system clock is the 16
MHz FIRC oscillator, the CPU is in supervisor mode, and all the
memory is available. Initialization is required before most peripherals may be used and before the SRAM
can be read (since the SRAM is protected by ECC, the syndrome will generally be uninitialized after reset
and reads would fail the check). Accessing disabled features causes error conditions or interrupts.
A typical startup routine would involve initializing the software environment including stacks, heaps,
variable initialization, and so on, and configuring the MCU for the application.
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