AN3307

Main differences between STM32F packages and their possible modifications

Doc ID 18186 Rev 4

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Verbose and diagnostic modes

Verbose messages can slightly vary between packages but they are mostly self-explanatory.

Users can easily find the calling place and condition at the source code from which the

message is published. Signals provided on GPIO LEDs can be used for basic check if the

application runs properly, as well as for measurement of some basic timing intervals. Be

sure the verbose messages increase the processing load at execution phase and

significantly increase an overhead of code memory capacity, especially.

Duration of the tests

The duration of the initial functional self-test performed at startup phase can vary slightly

depending on CPU clock frequency and size of memory areas tested. The differences

between duration of periodical run time self-tests are negligible and depend mainly on the

CPU clock. Both software RAM transparent and partial Flash tests last about 20 µs with

default block size setting (at CPU clock about 72 MHz).

Overall test RAM or Flash cycle duration depends on:

●

size of the memory area under check,

●

size of the block checked at one step and

●

frequency of the partial test steps.

For instance, a test of the RAM area collecting 32 pairs of word Class B variables needs 16

partial steps if 4 words are tested by one step (in fact, 6 words are tested at every step if just

one word overlap is configured at both the highest and the lowest address - follow the

transparent RAM test configuration).

Test of 64 KB of Flash can be done at 1024 partial steps when block size is set to default

16 words. This means overall duration of 10 s if period of steps is 10 ms.

At any critical case when such long interval for Flash testing is not acceptable, the program

memory can be divided into few sectors and the test can be reduced to be performed above

one selected sector just keeping the safety functions and data currently used.

Toggling of some LEDs can be used to measure the timing performance of the firmware. Be

sure any control of verbose messages used at debugging is disabled as well as initialization

of evaluation board display when doing any such measurement.