PXS20RM Datasheet, PDF (541/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Fault Collection and Control Unit (FCCU)
Figure 22-39 shows the FCCU configuration sequence after a power-on, ‘destructive’, or external reset.
phase1 phase2 phase3 self test
phase1 phase2
phase3
run
power-on, ‘destructive’,
external, or self-test
completed reset
FCCU configuration
from NVM
FCCU _CFG.PS,
FCCU_CFG.FOM,
FCCU_CFG.FOP
FCCU state
asynch
RESET
asynch
CONFIG
DEFAULT (reset value)
XXX
(STCU running)
RESET
NORMAL
XXX
(STCU running)
DEFAULT (reset value)
CONFIG
RESET
NORMAL CONFIG NORMAL
STCU state
RESET STDBY INIT
Self-checking
(running)
IDLE
FCCU_F[1:0]
(from FCCU)
FCCU_F[1:0]
(top)
High-Z
(STCU control)
High-Z
(reset)
High-Z
Figure 22-39. NVM interface
PROT1
High-Z
(MC control)
PROT2
PROT2
22.7.10 FCCU_F interface
The FCCU provides 2 external bidirectional signals (FCCU_F interface). Different protocols for the
FCCU_F interface are supported, selecting the FCCU_CFG.FOM register field:
• Dual rail protocol
• Time switching protocol
• Bi-stable protocol
• Test mode
The signal polarity and the frequency can be programmed, setting the FCCU_CFG.PS and
FCCU_CFG.FOP register fields. All the diagrams and tables are related to the default configuration
selection (FCCU_CFG.FOP = 0b), switching mode (FCCU_CFG.SM = 0b) and config mode
(FCCU_CFG.CM = 0b). In case of inverted polarity (FCCU_CFG.FOP = 1b) all the values on the FCCU_F
output pins are inverted.
2 modes can be programmed to define the FCCU_F protocol transitions in dual-rail or time-switching
mode:
• Slow switching mode: no FCCU_F frequency violation during the FCCU state transition
(NORMAL to ERROR or viceversa and CONFIG to NORMAL). The FCCU_F protocol transition
occurs after a max delay equal to the duration of the semi-period of the FCCU_F frequency.
• Fast switching mode: The FCCU_F protocol transition (NORMAL to ERROR or viceversa and
CONFIG to NORMAL) occurs immediately. A pulse with the minimum duration corresponding to
16 MHz / 1024 (IRCOSC clock) period can occurs in fast switching mode. It implies a frequency
violation of the FCCU_F protocol.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
22-41