SM CODE
DMA_SM_1
Addressed fault model
Permanent/transient
Dependency on
Device
configuration
None
Initialization
Depends on implementation
Periodicity
On demand
Test for the diagnostic
Not applicable
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
To give an example about checksum encoding capability, using just a bit-by-bit addition is
inappropriate.
Table 54.
DMA_SM_2
SM CODE
DMA_SM_2
Description
Information redundancy by including sender or receiver identifier on data packet transferred
via
DMA
Ownership
End user
Detailed implementation
This method helps to identify inside the MCU the source and the originator of the message
exchanged by
DMA
.
Implementation is realized by adding an additional field to protected message, with a
coding convention for message type identification fixed at
Device
level. Guidelines for the
identification fields are:
•
Identification field value must be different for each possible couple of sender or receiver
on
DMA
transactions.
•
Values chosen must be enumerated and non-trivial.
•
Coherence between the identification field value and the message type is checked by
Application software
before consuming data.
This method, when implemented in combination with DMA_SM_4, makes available a kind of
virtual channel
between source and destinations entities.
Error reporting
Depends on implementation
Fault detection time
Depends on implementation
Addressed fault model
Permanent/transient
Dependency on
Device
configuration
None
Initialization
Depends on implementation
Periodicity
On demand
Test for the diagnostic
Not applicable
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
None
Table 55.
DMA_SM_3
SM CODE
DMA_SM_3
Description
Periodic software test for
DMA
Ownership
End user
Detailed implementation
This method requires the periodical testing of the DMA basic functionality, implemented
through a deterministic transfer of a data packet from one source to another (for example
from memory to memory) and the checking of the correct transfer of the message on the
target. Data packets are composed by non-trivial patterns (avoid the use of 0x0000, 0xFFFF
values) and organized in order to allow the detection during the check of the following failures:
•
incomplete packed transfer
UM2305
Hardware and software diagnostics
UM2305
-
Rev 10
page 36/110
