ST STEVAL-IHM020V1, User Manual, Page: 17 / 23

UM0583 IEC 61000-4-4 Burst immunity test
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data. This maintains the previous switch state, for example, when a RESET occurs due
to an EMI problem. If, when checked, the RAM registers are not as expected, a
complete initialization procedure is launched. If the RAM area is adequate, then a
“smart reset” can be performed. Only the registers which are used to store internal sub-
routine variables are cleared, and only the main registers keep their previous values
(AC switch status, AC switch control, etc)
●
Use the watchdog properly. Enable the watchdog as soon as possible after reset and
never refresh the watchdog in an interrupt routine
●
Secure the unused program memory area. Fill the unused memory locations with code
that forces a watchdog reset or jumps to a known program location if you do not want to
generate a reset
●
Input filtering. Its recommended to read the AVF signal during several AC line cycles.
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