Safety Manual for MPC5777M, Rev. 1.1
Functional safety requirements for application software
NXP Semiconductors28
• The SWT time window settings shall be set to a value less than the FTTI. Detection latency shall
be smaller than the FTTI.
• Before the safety function is executed, the software shall verify that the SWT is enabled by reading
the SWT control register (SWT_CR).
3.2.22 Analog to Digital Converters
MPC5777M includes both SD and SAR ADCs. One of the SAR ADCs is considered the supervisor, or
monitor, ADC (for example, SAR ADCB). The others ADCs have normal functionality.
The basic idea to verify the integrity of the functional ADCs is to implement software redundancy. This
redundancy is supported by hardware allowing acquisition of analog inputs using independent ADC
modules
1
.
Figure 1 shows the block scheme of connection of the SAR ADCs, including the supervisor. Through a
second level of multiplexing, all analog inputs connected to the functional ADCs (both SD and SAR), are
connected to the supervisor ADC.
1.Simultaneous sampling of two ADCs on the same analog input is not allowed (see the MPC5777M Reference Man-
ual for details).
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