ST STM32F2 Series - Table 34. DMA_SM_2; Table 35. DMA_SM_3

Table 34. DMA_SM_2
SM CODE DMA_SM_2
Description Information redundancy 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 MCU 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 and Transient
Dependency on MCU configuration None
Initialization Depends on implementation
Periodicity On demand
Test for the diagnostic Not needed
Multiple faults protection CPU_SM_0: periodical core self-test software
Recommendations and known
limitations
None
Table 35. DMA_SM_3
SM CODE DMA_SM_3
Description Periodical 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
• Errors in single transferred word
• Wrong order in packed transmitted data
Error reporting Depends on implementation
Fault detection time Depends on implementation
Addressed fault model Permanent
Dependency on MCU configuration None
Initialization Depends on implementation
Periodicity Periodic
Test for the diagnostic Not needed
Multiple faults protection CPU_SM_0: periodical core self-test software
UM1845
Description of hardware and software diagnostics
UM1845 - Rev 4
page 30/108