Built In Self Tests in FS85

[haby_a]

What will happen when ABIST or LBIST tests fail in FS85. I understand that FS0B pin will be stuck low. How does FS85 behave after this; will watchdog windowing happens and refresh will be accepted by FS85 without shifting to normal mode? or will RSTB pin be asserted?

Also how ABIST2 test is launched via SPI ? Is it done by configuring FS_I_OVUV_SAFE_REACTION1 register during INIT_FS?

[TomasVaverka]

Hi Haby,

Yes, if ABIST1 (ABIST1_OK = 0) or LBIST (LBIST_OK = 0) fails, RSTB and PGOOD are released, but FS0B remains stuck low keeping the application in safe state. The Fail-safe state machine transitions to the INIT_FS state as usual.

As for the ABIST2, during INIT_FS, the MCU configures the ABIST2 coverage with the FS_I_OVUV_SAFE_REACTION1 register, assigning the voltage monitoring to be verified during ABIST2:

• VCOREMON_ABIST2 = 1 to verify VCOREMON comparators during ABIST2
• VDDIOMON_ABIST2 = 1 to verify VDDIOMON comparators during ABIST2
• VMONx_ABIST2 = 1 to verify VMONx comparators during ABIST2

As soon as INIT_FS is closed and the latest voltage regulator assigned to ABIST2 is started, ABIST2 is executed.

Best regards,

Tomas