MPC5604B/C Microcontroller Reference Manual, Rev. 8
26 Freescale Semiconductor
The MPC5604B internal logic operates from 1.2 V (nominal) supplies that are normally supplied by the
on-chip voltage regulator from a 5 V or 3.3 V supply. The 3.3–5 V (±10%) supply is also used to supply
the input/output pins on the MCU. Chapter 4, Signal description, describes the power supply pin names,
numbers and their purpose. For more detail on the voltage supply of each pin, see Chapter 11, Voltage
Regulators and Power Supplies. For specifications of the voltage ranges and limits and decoupling of the
power supplies see the MPC5604B data sheet.
Certain pins have dedicated functions that affect the behavior of the MCU after reset. These include pins
to force test or alternate boot conditions and debug features. These are described in Chapter 4, Signal
description, and a hardware designer should take care that these pins are connected to allow correct
operation.
Beyond power supply and pins that have special functions there are also pins that have special system
purposes such as oscillator and reset pins. These are also described in Chapter 4, Signal description. The
reset pin is bidirectional and its function is closely tied to the reset generation module [Chapter 9, Reset
Generation Module (MC_RGM)”]. The crystal oscillator pins are dedicated to this function but the
oscillator is not started automatically after reset. The oscillator module is described in Chapter 6, Clock
Description, 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 4.7, Functional ports. Inputs are selected using the PSMI registers; these are described
in Chapter 19, 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.
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