how to output RTCO on FRDM-KE02Z?

[jacquesnapoleon]

Hello,

Can I find some test codes allowing to output RTCO on PTC5 using FRDM-KE02Z?

Thanks and best regards,

Jacques.

[jeremyzhou]

Hi Jacques,

Please check the attachment.
Have a great day,
Ping

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[jacquesnapoleon]

Hi Jeremy,

Thanks for your reply.

I already had this kind of project taken from library.

Seems that this output RTCO coming from 1kHz LPO.

I would like to configure RTC clock gated from ICS, then controlling ICSIRCLK gate and SIM RTC/WDOG gate (refer to top of Figure 5-1 clocking diagram from RM).

The output frequency should be 32kHz.

I already tried this but this does not work up to now...

Many thanks and best regards,

Jacques.

[jeremyzhou]

Hi Jacques,

In the demo, the 1kHz LPO as the clock source of the RTC, and it's supported to select other clock source.

I was wondering if you can tell what issue you stuck in.

Have a great day,
Ping

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[jacquesnapoleon]

Hi Jeremy,

Thanks for your reply and you help on this topic.

I already tried this but it cannot make appearing 32kHz frequency to RTCO pin.

I only want to use 32kHz IRC as an external signal to drive external components...

I modified the initial code as shown below.

In that case, I observed ~19.73kHz on RTCO pin which it supposed to be the 39,0625kHz divided by 2 (?), as if PTC5 output FTM signal (ICSFFCLK/2) instead of ICSIRCLK... However, RTC0 pin is well assigned to PTC5 in SIM_PINSEL as RTCS = 1...

Thanks and best regards,

Have a nice day!

Jacques.

int main (void)

{

    uint8_t         u8Ch;

    ICS_ConfigType  sICSConfig;

    RTC_ConfigType  sRTCConfig;

    RTC_ConfigType  *pRTCConfig = &sRTCConfig;      

    UART_ConfigType sConfig;

    ICS_Trim(ICS_TRIM_VALUE);

    LED0_Init(); 

    LED2_Init();

    /* configure RTC to 1Hz interrupt frequency */

    pRTCConfig->u16ModuloValue = 0;

    pRTCConfig->bRTCOut=RTC_OUTPUT_ENABLE;

    pRTCConfig->bInterruptEn   = RTC_INTERRUPT_ENABLE;     /* enable interrupt */

    pRTCConfig->bClockSource   = RTC_CLKSRC_IREF;          /*clock source is 1khz*/

    pRTCConfig->bClockPresaler = RTC_CLK_PRESCALER_128;    /*prescaler is 100*/

    SIM->PINSEL |=SIM_PINSEL_RTCPS_MASK;

    RTC_SetCallback(RTC_Task);

    RTC_Init(pRTCConfig);

    /* Enable IRCLK */

    ICS->C1 |= 0x02;

    /* switch clock mode from FEE to FEI */

    sICSConfig.u32ClkFreq = 32;     /* NOTE: use value 32 for 31.25KHz to 39.0625KHz of internal IRC */

    ICS_SwitchMode(FEE,FEI, &sICSConfig);

    while(1)

    {

    }

}

[jeremyzhou · Accepted solution]

Hi Jacques,

According to the fig 1 illustrates , you'll learn that

                                                                          Fig 1

Have a great day,
Ping

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[jacquesnapoleon]

Hello Ping,

Thanks for your reply.

This could explain the frequency observed...

BTW, where this formula comes from, I did not find it in the reference manual...?

Thanks and best regards,

Jacques.

[jeremyzhou]

Hi Jacques,

The formula is created by myself, by using this formula, I think it can help you to understand it easily.
Have a great day,
Ping

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