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Thread: XMC4800 Interrupt by RTC_XTAL1

  1. #1
    New Member New Member Cris06 is on a distinguished road
    Join Date
    May 2018

    XMC4800 Interrupt by RTC_XTAL1

    I'd like to generate an IRQ by a falling edge on RTC_XTAL1. For this I can use ERU0, 1B1.
    Can someone tell me how to configurate the MCU for this purpose?
    Im using an XMC4800F144.

  2. #2
    Advanced Advanced
    Infineon Employee
    Infineon Employee
    DRubeša will become famous soon enough
    Join Date
    Jul 2016

    unfortunately, I don´t have a complete working solution but I guess it´s better to show you how it could be realized. Maybe you also notice some small detail that I missed.

    #include "xmc_scu.h"
    #include "xmc_gpio.h"
    #include "xmc_eru.h"
    const XMC_ERU_ETL_CONFIG_t eru_etl_config =
      .input_b = ERU0_ETL1_INPUTB_SCU_HIB_SR1,
      .enable_output_trigger = 1,
      .output_trigger_channel = XMC_ERU_ETL_OUTPUT_TRIGGER_CHANNEL1,
      .source = XMC_ERU_ETL_SOURCE_B,
      .status_flag_mode = XMC_ERU_ETL_STATUS_FLAG_MODE_SWCTRL,
      .edge_detection = XMC_ERU_ETL_EDGE_DETECTION_FALLING
    const XMC_ERU_OGU_CONFIG_t eru_ogu_config =
      .peripheral_trigger         = 0U, /* OGU input peripheral trigger */
      .enable_pattern_detection   = false, /* Enables generation of pattern match event */
      .service_request            = XMC_ERU_OGU_SERVICE_REQUEST_ON_TRIGGER, /* Interrupt gating signal */
      .pattern_detection_input    = 0U
    void IRQ_Hdlr_2 (void)
    	uint8_t index;
    	index = 0;			// used just to set the breakpoint, unfortunately this point in code is not reached
    int main(void)
      XMC_ERU_ETL_Init(XMC_ERU0, 1, &eru_etl_config);
      XMC_ERU_OGU_Init(XMC_ERU0, 1, &eru_ogu_config);
      XMC_SCU_HIB_RTCCLKSRC_t currentStdbyClock;
      if (XMC_SCU_HIB_IsHibernateDomainEnabled() == false)
      // this part is added just for testing, enabling low power EXTERNAL oscillator should be sufficient
      currentStdbyClock = XMC_SCU_HIB_GetStdbyClockSource();
      NVIC_SetPriority((IRQn_Type)2, NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 63, 0));
      /* Loop forever */
      while (1)
    The code doesn´t reach interrupt routine and there is not even status flag set which will signify that falling edge is detected. I´ve tried also with rising and both edges and it doesn´t seem to have an impact. When I tried the use some of the buttons with similar code (different board, different input pin, different ERU module and different interrupt service routine) I was successful, which may me lead that maybe the voltage level transition on a RTC_XTAL1 pin are not sufficient to trigger ERU module edge detection. But again, maybe this is working fine but there are some issues with initialization which currently I don´t see. So try it by yourself and see if you see some issues with the code.

    Best regards,
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

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