PXS20RM Datasheet, PDF (529/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Field
FSx
MCSx
Fault Collection and Control Unit (FCCU)
Table 22-25. FCCU_MCS field descriptions (continued)
Description
Fault status
It indicates that the correspondent MCSx field has been captured when the FCCU is in FAULT
state.
0: MCSx field captured in any state different from the FAULT state
1: MCSx field captured in FAULT state
These bits can be read by the software.
Chip mode
The MCSx is the chip mode.
MCS0 = latest state
MCS3 = oldest state
On any chip mode change the previous chip modes are shifted (MCS3 = MCS2, MCS2= MCS1,
MCS1= MCS0) and the latest one is captured in MCS0.
These bits can be read by the software.
22.7 Functional description
22.7.1 Definitions
In general, the following definitions are applicable for the fault management:
• HW recoverable fault: the fault indication is a level sensitive signal that is asserted as long as the
fault cause has not been removed. Typically the fault signal is latched in a external module at the
FCCU. The FCCU state transitions are consequently executed on the state changes of the input
fault signal. No SW intervention in the FCCU is required to recover the fault condition.
• SW recoverable fault: the fault indication is a signal asserted without a defined time duration. The
fault signal is captured in the FCCU. The fault recovery is executed following a SW recovery
procedure (status/flag register clearing).
The following type of reset are applicable (see Chapter 41, Reset Generation Module (MC_RGM)):
• ‘Destructive’ reset: any type of reset related to a power failure condition that implies a complete
system reinitialization
• Long ‘functional’ reset: it implies the flash memory and digital circuitry (most of it with some
exceptions FCCU, STCU) initialization
• short functional reset: it implies the digital circuitry (most of it with some exceptions FCCU,
STCU) initialization.
22.7.2 FSM description
The FCCU functionality is depicted by the FSM diagram given in Figure 22-26.
Basically four states are identified with the following meaning:
• CONFIG: the configuration state is used only to modify the default configuration of the FCCU. A
sub-set of the FCCU registers, dedicated to define the FCCU configuration (global configuration,
reactions to fault, time-out, non-critical fault masking) can be accessed in write mode only in the
CONFIG state.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
22-29