[MPC5777C] FCCU Isr is occured by STCU2

Showing results for 
Search instead for 
Did you mean: 

[MPC5777C] FCCU Isr is occured by STCU2

Contributor III

Dear NXP engineers,

I just want to make sure this symptom is normal or abnormal thing.

MCU : NXP MPC5777C 3N45H

Compiler : WindRiver DIab

Operating system clock : 264Mhz


I tested with on-line tset code(MPC5777C_on-line_bist_3N45H.c) at AN5288 "MPC5777C STCU Quick Start Guide"

This is test sequence

1. Core 1 is halted and reset.

2. Core 0 is running only

3. Execute run_online_bists()

4. FCCU Isr is invoked

I have been set to FCCU register, especially, 10th RCCU_0, 23rd PLL_0 are set.

5. FCCU detect RCCU_0, PLL_0 fault during on-line bist.

like below, Captured from T32 PowerView


I think FCCU check Core 0 and Core1, RCCU. So FCCU could detect fault even though It is not real fault.

Also I could see our system come back to normal operating mode after on-line bist is completed. Of course there is running reset due to STCU.

Do you think so? Or I should change configuration?

Please give me your feedback.


Best regards,


0 Kudos
2 Replies

NXP Employee
NXP Employee


There should be no errors in FCCU if BIST is successful.

Are you also running offline BIST?

Because this one is started after your Online BIST finished and performed reset.

Those faults can also come from this execution.


0 Kudos

Contributor III

Thank you, Peter

I have an additional question about execution time for on-line bist.

I did measure execution time of lbist with "MPC5777C_on-line_lbit_3N45H.c"

Also I configured PLL as recommended value which is in the AN5288(Rev 0), 11 ~ 12page.

Like below,

PLLDIG.PLL0DV.R = 0x2006200F;
SIU.SYSDIV.R = 0x0000B010;

Because We use 40MHz external x-tal and I think it is very similar to example.

I didn't change remaining configuration. I did use original configuration.

But, Test result is different from calculated value.

According to "MPC5777C_BIST_Execution_Time_protected_v2.0.xlsx", lbist execution time is approximately 22.38ms.

However, Actual measured time is 32.3ms. It is longer than calculated value.

Does it valid result? or Test sample code is old version?

Please let me know.

0 Kudos