AN3307

Class B solution structure

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5.4.2

CPU light runtime self-test

The light runtime CPU core self-tests is a simplified version of the runtime test described in

Section 5.4.1: Runtime self-test structure. The flags and stack pointers are not tested. If an

error code is returned the Fail Save procedure is called.

Figure 16.

CPU light runtime self-test structure

5.4.3

Stack boundaries runtime test

This test checks the magic pattern stored at the top of the space reserved for the stack. If

the original pattern is corrupted, the Fail Safe routine is called. The pattern is placed at the

lowest address reserved for the stack area. It can detect both overflow and underflow as the

stack pointer rolls over this range in either case. The stack area differs depending on the

specific microcontroller device type. Be careful of the stack area limits when the location of

the pattern is changed.

Figure 17.

Stack overflow runtime test structure

MS18902V1

Push R0 - R 13

Pop R0 – R13

Test OK

Fail Safe routine

Test R0 – R13

Fail

Verify ramp pattern R 0 – R13

Fail

Test OK

FailSafe () routine

Fail

Any

difference

?

Yes

No

AI18013

Check lower pattern