Class B solution structure

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Doc ID 17286 Rev 2

Figure 10.

Clock startup self test subroutine structure

1.

Low speed external (LSE) clock source can be started/checked at the beginning of the test and measured

feeding the dedicated timer on STM8L15x devices. They can be inserted into the beginning of this routine.

2.

High speed external (HSE) tests are skipped on STM8L10x devices.

3.

LSI frequency is different for STM8S and STM8L devices. That is why the four consequent LSI periods are

gated at STM8S devices (LSI=128 kHz) and only one period is used for measure on STM8L devices

(LSI=38 kHz).

4.3

Periodic run mode self tests initialization

Run time self tests must be initialized just before the program enters the main loop

performing the run mode self tests (refer to Figure 4). This must come just after start-up self

tests have been executed and standard initialization done. The timing should be set to

ensure that run mode tests are called properly and at regular intervals.

All class B variables must first be initialized. Zero and its complement value are stored in

every class B variable complementary pair. The magic pattern is than stored at the top of

stack space. Timer peripherals are configured for the tick interval measurement and master

clock frequency measurement. Master frequency is gated by the LSI clock. The same

method as for startup test is used. The resulting number of pulses is stored into the class B

variable pair as an initial reference sample of master frequency measure.