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RIOT/cpu/lpc1768/periph/timer.c 3.59 KB
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  /*
   * Copyright (C) 2014 Freie Universitรคt Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser General
   * Public License v2.1. See the file LICENSE in the top level directory for more
   * details.
   */
  
  /**
   * @ingroup     cpu_lpc1768
   * @ingroup     drivers_periph_timer
   * @{
   *
   * @file
   * @brief       Implementation of the low-level timer driver for the LPC1768
   *
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   * @}
   */
  
  #include <stdint.h>
  
  #include "cpu.h"
  #include "periph_conf.h"
  #include "periph/timer.h"
  
  /* guard file in case no timers are defined */
  #if TIMER_0_EN
  
  /**
   * @name Timer channel interrupt flags
   * @{
   */
  #define MR0_FLAG    (0x01)      /**< match for channel 0 */
  #define MR1_FLAG    (0x02)      /**< match for channel 1 */
  #define MR2_FLAG    (0x04)      /**< match for channel 2 */
  #define MR3_FLAG    (0x08)      /**< match for channel 3 */
  /** @} */
  
  /**
   * @brief UART device configurations
   */
  static timer_isr_ctx_t config[TIMER_NUMOF];
  
  int timer_init(tim_t dev, unsigned long freq, timer_cb_t cb, void *arg)
  {
      if (dev == TIMER_0) {
          /* save callback */
          config[TIMER_0].cb = cb;
          config[TIMER_0].arg = arg;
          /* enable power for timer */
          TIMER_0_CLKEN();
          /* let timer run with full frequency */
          TIMER_0_PLKSEL();
          /* set to timer mode */
          TIMER_0_DEV->CTCR = 0;
          /* configure prescaler */
          TIMER_0_DEV->PR = (TIMER_0_FREQ / freq) - 1;
          /* configure and enable timer interrupts */
          NVIC_SetPriority(TIMER_0_IRQ, TIMER_IRQ_PRIO);
          NVIC_EnableIRQ(TIMER_0_IRQ);
          /* enable timer */
          TIMER_0_DEV->TCR |= 1;
          return 0;
      }
      return -1;
  }
  
  int timer_set_absolute(tim_t dev, int channel, unsigned int value)
  {
      if (dev == TIMER_0) {
          switch (channel) {
              case 0:
                  TIMER_0_DEV->MR0 = value;
                  break;
              case 1:
                  TIMER_0_DEV->MR1 = value;
                  break;
              case 2:
                  TIMER_0_DEV->MR2 = value;
                  break;
              case 3:
                  TIMER_0_DEV->MR3 = value;
                  break;
              default:
                  return -1;
          }
          TIMER_0_DEV->MCR |= (1 << (channel * 3));
          return 1;
      }
      return -1;
  }
  
  int timer_clear(tim_t dev, int channel)
  {
      if (dev == TIMER_0 && channel >= 0 && channel < TIMER_0_CHANNELS) {
          TIMER_0_DEV->MCR &= ~(1 << (channel * 3));
          return 1;
      }
      return -1;
  }
  
  unsigned int timer_read(tim_t dev)
  {
      if (dev == TIMER_0) {
          return (unsigned int)TIMER_0_DEV->TC;
      }
      return 0;
  }
  
  void timer_start(tim_t dev)
  {
      if (dev == TIMER_0) {
          TIMER_0_DEV->TCR |= 1;
      }
  }
  
  void timer_stop(tim_t dev)
  {
      if (dev == TIMER_0) {
          TIMER_0_DEV->TCR &= ~(1);
      }
  }
  
  #if TIMER_0_EN
  void TIMER_0_ISR(void)
  {
      if (TIMER_0_DEV->IR & MR0_FLAG) {
          TIMER_0_DEV->IR |= (MR0_FLAG);
          TIMER_0_DEV->MCR &= ~(1 << 0);
          config[TIMER_0].cb(config[TIMER_0].arg, 0);
      }
      if (TIMER_0_DEV->IR & MR1_FLAG) {
          TIMER_0_DEV->IR |= (MR1_FLAG);
          TIMER_0_DEV->MCR &= ~(1 << 3);
          config[TIMER_0].cb(config[TIMER_0].arg, 1);
      }
      if (TIMER_0_DEV->IR & MR2_FLAG) {
          TIMER_0_DEV->IR |= (MR2_FLAG);
          TIMER_0_DEV->MCR &= ~(1 << 6);
          config[TIMER_0].cb(config[TIMER_0].arg, 2);
      }
      if (TIMER_0_DEV->IR & MR3_FLAG) {
          TIMER_0_DEV->IR |= (MR3_FLAG);
          TIMER_0_DEV->MCR &= ~(1 << 9);
          config[TIMER_0].cb(config[TIMER_0].arg, 3);
      }
      cortexm_isr_end();
  }
  #endif
  
  #endif /* TIMER_0_EN */