topic Re: Selecting the FDIV value for FLASH in in S32K

Selecting the FDIV value for FLASH in

Sourdev — Mon, 06 Mar 2023 10:54:13 GMT

My question is about selecting the FDIV value for FLASH.

I am using the FEE(FLL Engaged External) Mode.

External Osc = 16MHz

RDIV = 512

Input to the FLL = 16MHz / 512 = 31250

FLL Output = 31250 * 1024 = 32MHz

but I want a 40MHz core clock, So I set BUSDIV bit before changing ICS_C2[BDIV]=0x000. As given in the reference manual.

After doing this, we get Core clock = 40Mhz and Bus/FLASH clock = 20MHz.

Can we use FDIV = 0x13 value? Because in the reference manual, there is one NOTE which tells not to use maximum value. Which value we are considering too High = 0x13 or FDIV[5:0] 2^6 = 64?

So is it safe to use FLASH for 20MHz?

Re: Selecting the FDIV value for FLASH in

Robin_Shen — Tue, 07 Mar 2023 01:01:22 GMT

Hi Sourdev,

If you are using FRDM-KEAZ64Q64(S9KEAZ64AMLH), please note that you should read KEA128RM and S9KEA128P80M48SF0.

Notice: In FEE mode, FLL output frequency = OSC/RDIV *1280.

For that NOTE, configure FTMRE_FCLKDIV[FDIV] between fNVMOP.

You can set Core clock = 40Mhz and Bus/FLASH clock = 20MHz.

Best Regards,
Robin
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Re: Selecting the FDIV value for FLASH in

Sourdev — Tue, 07 Mar 2023 02:39:10 GMT

Hi Robin_Shen,

I am using S9KEAZN64AMLC.

In that FLL Output = (OSC/RDIV)*1024.

given in (reference manual KEA64RM)

Re: Selecting the FDIV value for FLASH in

Robin_Shen — Tue, 07 Mar 2023 13:20:28 GMT

If you have to use 16MHz crystal as clock source with FEE mode, then the frequency of the Core clock will be 32MHz, and the frequency of the Bus\Flash clock will be 16MHz.

For 40MHz Core clock and 20MHz Bus\Flash clock, you may need to use 10MHz crystal with FEE.