mc9s12xeq512 mcu & flash initialiation

[Eric_t]

Hi!

I have download from NXP demo example project for programming the internal flash memory of XEP controllers.

The project that I download is "XEP100-FLASH-PFLASH-CW51"

The project works just fine, but the problem that I am facing, is that it is not clear what is the correct frequency that I should enter in PFLASH_Init routine.

"PFLASH_Init routine"

//==============================================================================
//PFLASH_Init
//==============================================================================
void PFLASH_Init(unsigned char fdiv)
{
while(FSTAT_CCIF == 0); //wait if command in progress
FCLKDIV = fdiv; //osc = 16MHz
}

the main calls it as follow

  PFLASH_Init(0x0F);//oscillator 16MHz

So, it gives 0x15 for 16MHz oscillation. 

I will use the PLL with High speed (internal bus clock 50MHz), Low speed (internal bus clock 14.75MHz), Slow speed (internal bus clock 4MHz).

The problem is that PFLASH_Init has no comments about the formula of oscillation and the operant of "PFLASH_Init routine"

Could someone from NXP tell me how can I calculate the operant of "PFLASH_Init routine" when the internal bus clockis 50, 14.75 and 4MHz?

Thank you

Original Attachment has been moved to: XEP100-FLASH-PFLASH-CW51.ZIP

[lama · Accepted solution]

Hi,

yes, the value 0x0F because the flash clock is derived from oscillator clock. The only what is different is PLL setup for BUSCLK.

Ups, I have forgotten. the data sheet also presents:

Best regards,

Ladislav

[lama]

Hi,

please go to our pages and you can find there calculator at the page:

S12XE MCUs|16-Bit Microcontroller|NXP 

Or directly:

https://www.nxp.com/downloads/en/calculators/S12XESW.zip 

The answer is:

Best regards,

Ladislav

[Eric_t]

Hi lama,

Thank you for the quick answer.

As far as I understand, the FCLKDIV   of "PFlash_Ini" routine, is the "FDIV" of S12XEiPLL calculator, and in all cases it should be 0x0F.

Is that correct?

Thank you.