tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC15XX/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_IRQn     RIT_IRQn
  21
  22 int us_ticker_inited = 0;
  23
  24 void us_ticker_init(void) {
  25     if (us_ticker_inited) return;
  26     us_ticker_inited = 1;
  27
  28     // Enable the RIT clock
  29     LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << 1);
  30
  31     // Clear peripheral reset the RIT
  32     LPC_SYSCON->PRESETCTRL1 |= (1 << 1);
  33     LPC_SYSCON->PRESETCTRL1 &= ~(1 << 1);
  34
  35     LPC_RIT->MASK = 0;
  36     LPC_RIT->MASK_H = 0;
  37
  38     LPC_RIT->COUNTER = 0;
  39     LPC_RIT->COUNTER_H = 0;
  40
  41     LPC_RIT->COMPVAL = 0xffffffff;
  42     LPC_RIT->COMPVAL_H = 0x0000ffff;
  43
  44     // Timer enable, enable for debug
  45     LPC_RIT->CTRL = 0xC;
  46
  47     NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
  48     NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
  49 }
  50
  51 uint32_t us_ticker_read() {
  52     if (!us_ticker_inited)
  53         us_ticker_init();
  54
  55     uint64_t temp;
  56     temp = LPC_RIT->COUNTER | ((uint64_t)LPC_RIT->COUNTER_H << 32);
  57     temp /= (SystemCoreClock/1000000);
  58     return (uint32_t)temp;
  59 }
  60
  61 void us_ticker_set_interrupt(timestamp_t timestamp) {
  62         uint64_t temp = ((uint64_t)timestamp * (SystemCoreClock/1000000));
  63     LPC_RIT->COMPVAL = (temp & 0xFFFFFFFFL);
  64     LPC_RIT->COMPVAL_H = ((temp >> 32)& 0x0000FFFFL);
  65 }
  66
  67 void us_ticker_disable_interrupt(void) {
  68     LPC_RIT->CTRL |= (1 << 3);
  69 }
  70
  71 void us_ticker_clear_interrupt(void) {
  72     LPC_RIT->CTRL |= (1 << 0);
  73 }