PXS20RM Datasheet, PDF (140/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Functional Safety
7.3.2 Software-triggered BIST during operation
For some modules of this device it is required to run BIST during operation, because testing every 10 hours
(Trip Time) is not sufficient for the targeted safety integrity level. These BIST runs need to be triggered
by application software once within each Process Safety Time (10 ms). Details are specified in the Safety
Application Guide.
Modules which require BIST runs during application are:
• ADC: Software triggers several self-tests implemented in hardware
• Flash memory ECC logic test
7.3.3 Software-triggered self-tests after boot
In order to ensure integrity of flash memory for a safety application, hardware based flash self-test needs
to be triggered by software every time the device is booted. Details are specified in the Safety Application
Guide.
7.4 Memory error detection and correction
RAMs are protected against soft errors by a 7-bit/32 SEC/DED ECC code computed over address and data
at each memory access. Detected faults are reported to the FCCU.
NVM Flash is protected by 8-bit/64 parity SEC/DED.
7.5 Monitoring
All monitoring features react within the so-called Process Safety Time of 10 ms or faster.
Core voltage is equipped with a low voltage detector and a high voltage detector to indicate if voltage is
out of the specified range. IO voltage is monitored by a low voltage detector. The voltage detectors
themselves have a hardware based self-checking feature.
This device is equipped with two temperature sensors.
Four clocks are monitored:
• Internal oscillator clock
• FMPLL-generated system clock
• FlexRay clock
• SMC clock
A Memory Protection Unit prevents incorrect memory accesses based on 16 possibly overlapping physical
memory regions.
PXS20 Microcontroller Reference Manual, Rev. 1
7-2
Freescale Semiconductor