PXS20RM Datasheet, PDF (544/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Fault Collection and Control Unit (FCCU)
As long as FCCU is in NORMAL or ALARM state, outputs will show “non-faulty“ signal. Output pins
#0, #1 will toggle between “01” and “10” with a given frequency. By default the frequency is the IRCOSC
clock frequency divided by 18*1024.
In the FAULT state, the output pin FCCU_F[0] is set as low.
In Time Switching mode the second output (FCCU_F[1]) is the inverted signal of first output
(FCCU_F[0]). Values 00 on the outputs indicate a fault in the error out protocol itself. This state must be
considered as critical fault, because no reliable error out indication is available any more.
In the RESET phase the output pins are set as “high impedance”.
NOTE
Figure 22-42 is formatted to display the behavior in all four phases (reset,
normal, error, and config), not to imply transitions between one phase to
another. In particular, transition from error phase to config phase is not
possible.
Reset phase
or self-test
Normal phase
Error phase
Config phase
FCCU_F[0]
FCCU_F[1]
Input
or high-Z
Output
Figure 22-42. Time-switching protocol
22.7.10.3 Bi-stable protocol
The encoding scheme is given in Table 22-30 and the related timing diagram is given in Figure 22-43.
Table 22-30. Bi-stable encoding
Logical state
non-faulty
faulty
reset
configuration
Bi-stable encoding
(output pins FCCU_F[1:0])
Note
01
10
high-Z
10
= non-faulty
no toggling
no toggling
no toggling
when FCCU_CFG.CM = 0
when FCCU_CFG.CM = 1
22-44
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor