void timer2_setup(void)
{
  // gpio_set(GPIOD, GPIO12);
  /*Enable AF clock*/
  rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPAEN);
  rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPBEN);
  /*
   * Set TIM3 channel output pins to
   * 'output alternate function push-pull'.
   */
  gpio_mode_setup(GPIOA, GPIO_MODE_AF,
                GPIO_PUPD_NONE, GPIO5);
  /*TIM3 CH3, CH4 as alternate functions*/
  gpio_set_af(GPIOA, GPIO_AF1, GPIO5);

  gpio_mode_setup(GPIOB, GPIO_MODE_AF,
                GPIO_PUPD_NONE, GPIO3|GPIO10|GPIO11);
  /*TIM3 CH3, CH4 as alternate functions*/
  gpio_set_af(GPIOB, GPIO_AF1, GPIO3|GPIO10|GPIO11);

  /* Enable TIM3 clock. */
  rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM2EN);
  setup_periodic_timer(TIM2, 15000);
  // timer_enable_counter(TIM3);
  // /* Reset TIM1 peripheral. */
  timer_reset(TIM2);
  // /* Timer global mode:
  //  * - No divider
  //  * - Alignment, center with mode 3* see manual for details
  //  * - Direction up
  //  */
  timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_CENTER_1, TIM_CR1_DIR_UP);

  // /* Set prescaler value for TIM1. */
  // timer_set_prescaler(TIM3, prescale);

  timer_set_oc_mode(TIM2, TIM_OC1, TIM_OCM_PWM1);
  timer_set_oc_mode(TIM2, TIM_OC2, TIM_OCM_PWM1);
  timer_set_oc_mode(TIM2, TIM_OC3, TIM_OCM_PWM1);
  timer_set_oc_mode(TIM2, TIM_OC4, TIM_OCM_PWM1);
  // /* Reenable outputs. */
  timer_enable_oc_output(TIM2, TIM_OC1);
  timer_enable_oc_output(TIM2, TIM_OC2);
  timer_enable_oc_output(TIM2, TIM_OC3);
  timer_enable_oc_output(TIM2, TIM_OC4);
  // timer_enable_break_main_output(TIM3);
  // /* ARR reload enable. */
  // timer_enable_preload(TIM3);
  // /* Pnce the configuration is done and the lines are enabled again, */
  // /* we reload the TIM3 */

  // /* Set the initial capture compare value for OC1. */
  // //this will be changed later to: initial_duty_cycle*pwm_period_ARR
  timer_set_oc_value(TIM2, TIM_OC1, 65535);
  timer_set_oc_value(TIM2, TIM_OC2, 65535);
  timer_set_oc_value(TIM2, TIM_OC3, 65535);
  timer_set_oc_value(TIM2, TIM_OC4, 65535);
  // /* Sets the Period for TIM1 PWM, named ARR. Set the defines in motordrive.c */
  // timer_set_period(TIM3,pwm_period_ARR);
  // /* Sets TIM1 Continuous mode. */
  // // timer_continuous_mode(TIM3);
  timer_enable_counter(TIM2);

  /* Enable capture/compare interrupt. */
  timer_enable_irq(TIM2, TIM_SR_UIF);
  //DO NOT ENABLE 2 timer IRQs!
  // timer_enable_irq(TIM3, TIM_DIER_CC4IE);

  nvic_enable_irq(NVIC_TIM2_IRQ);
  // nvic_set_priority(NVIC_TIM3_IRQ, 1);

}

void tim2_isr (void)//TIM3 CC interruption
{
  timer_clear_flag(TIM2, TIM_SR_UIF);
  printf("Blah\r\n");
}

void setup_periodic_timer(uint32_t timer, unsigned int freq_in_hz)
{
    unsigned int prescaler = 1;
    while (system_freq / prescaler / freq_in_hz > 0xffff)
        prescaler *= 2;
    timer_reset(timer);
    timer_set_prescaler(timer, prescaler-1);
    // printf("%u\r\n", system_freq / prescaler / freq_in_hz);
    timer_set_period(timer, system_freq / prescaler / freq_in_hz);
    timer_direction_down(timer);
    timer_enable_preload(timer);
}