CMU bus clock and how to map to FCCU fault

[zhucc]

In the process of using CMU module, I encountered the following two problems

1. In the formula for calculating the minimum value of RCCR[REF_CNT], one parameter is fbus_clock. How to determine the value of fbus_clock?

2.How do I configure the fault that the CMU detects that the frequency is too high or too low mapped to the corresponding FCCU fault? If I enable the corresponding FCCU fault, the FCCU fault is not triggered when the CMU detects a clock fault？

[alejandro_e]

Hello @zhucc, 

Thanks a lot for your patience. About the meaning/value of Fbus_clock, it is equivalent to the "module clock", you can see this in table 107 of the reference manual [page 581, S32G2 Reference Manual, Rev. 8, February 2024]:

you can double check it in the generated code of a project, for instance in the example Mcu_Example_S32G274A_M7, file  RTD\src\Clock_Ip_Data.c, using the DDR_CLK as example, since all the elements of this array use XBAR_DIV6_CLK: 

Therefore the frequency of the Fbus_clock, in this case, will be 4MHz:

Please also check section 23.8.2 [page 856 and onwards, S32G2 Reference Manual, Rev. 8, February 2024]:

 

Let me know if this information answers your question.

[zhucc]

thanks for your answer！Now，I know how to get the value of fbus_clock.On the second question I mentioned,how do I map the faults detected by the CMU module to the FCCU?I have enabled NCF[28] corresponding to CMU_REPORT_0.No FCCU fault is triggered when CMU_FC_22 has detected a clock error.

[alejandro_e]

Hello @zhucc,

I will ask the internal team if we hace any example on how to configure a FCCU fault with the CMU. However, I need the following information first:

• Are you using S32G2 or S32G3? I used S32G2 as reference in my last message
• Which RTD version are you using?

Thanks in advance.

[zhucc]

I am using S32G2.The RTD version is SW32G_RTD_4.4_4.0.2.Thanks!

[alejandro_e]

Hello @zhucc,

Thanks for the information, I will share it with the internal team and let you know if they have an example/guide on how to configure the FCCU fault.

I appreciate your patience.

[alejandro_e]

Hello @zhucc,

the internal team has shared the following:

"

If the customer requires to map the CMU event to FCCU fault, the corresponding CMU_IER register needs to be configured.  For an example, please check the Mcu_Example_S32G274A_M7.

" 

Please let me know if this information helped you.

[alejandro_e]

Hello @zhucc,

Please allow me some time to investigate the answers to your questions. 

Thanks for your patience.

Best regards