#include <xmc_common.h>

void initCCU4(void);
void connectLED(void);

int main(void) {

  initCCU4();

  while (1) {
  };
  return 0;
}

void initCCU4() {
  // step2: release reset of CCU40, all following lines are equal
  //*(0x500414) = 0b100;
  // SCU_RESET->PRCLR0 = 0b100;
  SCU_RESET->PRCLR0 = SCU_RESET_PRCLR0_CCU40RS_Msk;

  // step 3
  SCU_CLK->CLKSET = SCU_CLK_CLKSET_CCUCEN_Msk;

  // step 4
  CCU40->GIDLC = CCU4_GIDLC_SPRB_Msk;

  // step 6: period value & compare value for PWM
  // choose 0xffff to be most flexible & granular
  CCU40_CC42->PRS = 0xffff;
  // CCU40_CC42->PSC = 0b1010;
  CCU40_CC42->CRS = 0xffff * (1 - 0.1);
  CCU40->GCSS = CCU4_GCSS_S2SE_Msk;

  // connect led before CCU is started
  connectLED();

  // step 8
  CCU40->GIDLC = CCU4_GIDLC_CS2I_Msk;

  // step 9
  CCU40_CC42->TCSET = CCU4_CC4_TCSET_TRBS_Msk;
}

void connectLED() {
  const static uint8_t ALT3 = 0b10011;
  PORT1->IOCR0 =
      (PORT1->IOCR0 & ~PORT0_IOCR0_PC1_Msk) | (ALT3 << PORT0_IOCR0_PC1_Pos);
}