tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/us_ticker.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  * Ported to NXP LPC43XX by Micromint USA <support@micromint.com>
  17  */
  18 #include <stddef.h>
  19 #include "us_ticker_api.h"
  20 #include "PeripheralNames.h"
  21
  22 #define US_TICKER_TIMER      ((LPC_TIMER_T *)LPC_TIMER3_BASE)
  23 #define US_TICKER_TIMER_IRQn TIMER3_IRQn
  24
  25 int us_ticker_inited = 0;
  26
  27 void us_ticker_init(void) {
  28     if (us_ticker_inited) return;
  29     us_ticker_inited = 1;
  30
  31     US_TICKER_TIMER->CTCR = 0x0; // timer mode
  32     uint32_t PCLK = SystemCoreClock;
  33
  34     US_TICKER_TIMER->TCR = 0x2;  // reset
  35
  36     uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
  37     US_TICKER_TIMER->PR = prescale - 1;
  38     US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
  39
  40     NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
  41     NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
  42 }
  43
  44 uint32_t us_ticker_read() {
  45     if (!us_ticker_inited)
  46         us_ticker_init();
  47
  48     return US_TICKER_TIMER->TC;
  49 }
  50
  51 void us_ticker_set_interrupt(timestamp_t timestamp) {
  52     // set match value
  53     US_TICKER_TIMER->MR[0] = (uint32_t)timestamp;
  54     // enable match interrupt
  55     US_TICKER_TIMER->MCR |= 1;
  56 }
  57
  58 void us_ticker_disable_interrupt(void) {
  59     US_TICKER_TIMER->MCR &= ~1;
  60 }
  61
  62 void us_ticker_clear_interrupt(void) {
  63     US_TICKER_TIMER->IR = 1;
  64 }