tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/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 #include <stddef.h>
  17 #include "us_ticker_api.h"
  18 #include "PeripheralNames.h"
  19
  20 #define US_TICKER_TIMER          ((LPC_CTxxBx_Type *)LPC_CT32B1_BASE)
  21 #define US_TICKER_TIMER_IRQn     TIMER_32_1_IRQn
  22
  23 int us_ticker_inited = 0;
  24
  25 void us_ticker_init(void) {
  26     if (us_ticker_inited) return;
  27     us_ticker_inited = 1;
  28
  29     LPC_SYSCON->SYSAHBCLKCTRL |= (1<<10); // Clock TIMER_1
  30     uint32_t PCLK = SystemCoreClock;
  31
  32     US_TICKER_TIMER->TCR = 0x2;  // reset
  33
  34     uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
  35     US_TICKER_TIMER->PR = prescale - 1;
  36     US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
  37
  38     NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
  39     NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
  40 }
  41
  42 uint32_t us_ticker_read() {
  43     if (!us_ticker_inited)
  44         us_ticker_init();
  45
  46     return US_TICKER_TIMER->TC;
  47 }
  48
  49 void us_ticker_set_interrupt(timestamp_t timestamp) {
  50     // set match value
  51     US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
  52     // enable match interrupt
  53     US_TICKER_TIMER->MCR |= 1;
  54 }
  55
  56 void us_ticker_disable_interrupt(void) {
  57     US_TICKER_TIMER->MCR &= ~1;
  58 }
  59
  60 void us_ticker_clear_interrupt(void) {
  61     US_TICKER_TIMER->IR = 1;
  62 }