PXS20RM Datasheet, PDF (501/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Fault Collection and Control Unit (FCCU)
Chapter 22
Fault Collection and Control Unit (FCCU)
22.1 Introduction
The Fault Collection and Control Unit (FCCU) offers a programmable redundant hardware channel to
collect errors and to lead the device in a controlled way to a safe state when a failure is present in the
device. No CPU intervention is requested for collection and control operation.
The FCCU offers a systematic approach to manage fault detection and control.
The main functions supported by the module are:
• Redundant collection of hardware checker (for example, RCCU) results
• Redundant collection of error information from critical modules on the chip (such as the flash
memory or the STCU)
• Collection of test results
• Configurable and graded fault control via user software control
• Internal reactions:
— No reset reaction
— IRQ
— Short ‘functional’ reset
— Long ‘functional’ reset
— SAFE mode request
• External reaction (failure is reported to the outside world via output pins)
• Watchdog timer for the re-configuration phase
• Configuration lock
• NVM configuration loading
• Self checking capabilities:
— FCCU internal control logic redundancy
— Additional parity check for the associated configuration registers
The FCCU circuitry is checked at start-up by the self-checking procedure. The FCCU is operative with a
default configuration (without CPU intervention) immediately after the completion of the self-checking
procedure.
Two classes of faults — critical and non-critical — are identified based on the criticality and the related
reactions. Internal (short or long ‘functional’ reset, interrupt request) and external (FCCU_F signaling)
reactions are statically defined or programmable based on the fault criticality. The default configuration
can be modified only in a specific FCCU state for application/test/debugging purposes.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
22-1