Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_NXP/TARGET_LPC15XX/us_ticker.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2013 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #include <stddef.h>
elessair 0:f269e3021894 17 #include "us_ticker_api.h"
elessair 0:f269e3021894 18 #include "PeripheralNames.h"
elessair 0:f269e3021894 19 #include "critical.h"
elessair 0:f269e3021894 20
elessair 0:f269e3021894 21 #define US_TICKER_TIMER_IRQn SCT3_IRQn
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 int us_ticker_inited = 0;
elessair 0:f269e3021894 24
elessair 0:f269e3021894 25 void us_ticker_init(void) {
elessair 0:f269e3021894 26 if (us_ticker_inited)
elessair 0:f269e3021894 27 return;
elessair 0:f269e3021894 28
elessair 0:f269e3021894 29 us_ticker_inited = 1;
elessair 0:f269e3021894 30
elessair 0:f269e3021894 31 // Enable the SCT3 clock
elessair 0:f269e3021894 32 LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << 5);
elessair 0:f269e3021894 33
elessair 0:f269e3021894 34 // Clear peripheral reset the SCT3
elessair 0:f269e3021894 35 LPC_SYSCON->PRESETCTRL1 |= (1 << 5);
elessair 0:f269e3021894 36 LPC_SYSCON->PRESETCTRL1 &= ~(1 << 5);
elessair 0:f269e3021894 37
elessair 0:f269e3021894 38 // Configure SCT3 as a 1MHz 32-bit counter with no auto limiting or match reload
elessair 0:f269e3021894 39 char sctClkDiv = ((SystemCoreClock + 1000000 - 1) / 1000000) - 1;
elessair 0:f269e3021894 40 LPC_SCT3->CONFIG = (1 << 7) | (1 << 0);
elessair 0:f269e3021894 41 LPC_SCT3->CTRL = (sctClkDiv << 5) | (1 << 3) | (1 << 2);
elessair 0:f269e3021894 42
elessair 0:f269e3021894 43 // Configure SCT3 event 0 to fire on match register 0
elessair 0:f269e3021894 44 LPC_SCT3->EV0_STATE = (1 << 0);
elessair 0:f269e3021894 45 LPC_SCT3->EV0_CTRL = (0x1 << 12);
elessair 0:f269e3021894 46
elessair 0:f269e3021894 47 // Start SCT3
elessair 0:f269e3021894 48 LPC_SCT3->CTRL &= ~(1 << 2);
elessair 0:f269e3021894 49
elessair 0:f269e3021894 50 // Set SCT3 interrupt vector
elessair 0:f269e3021894 51 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
elessair 0:f269e3021894 52 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
elessair 0:f269e3021894 53 }
elessair 0:f269e3021894 54
elessair 0:f269e3021894 55 uint32_t us_ticker_read() {
elessair 0:f269e3021894 56 if (!us_ticker_inited)
elessair 0:f269e3021894 57 us_ticker_init();
elessair 0:f269e3021894 58
elessair 0:f269e3021894 59 // Return SCT3 count value
elessair 0:f269e3021894 60 return LPC_SCT3->COUNT;
elessair 0:f269e3021894 61 }
elessair 0:f269e3021894 62
elessair 0:f269e3021894 63 void us_ticker_set_interrupt(timestamp_t timestamp) {
elessair 0:f269e3021894 64 // Set SCT3 match register 0 (critical section)
elessair 0:f269e3021894 65 core_util_critical_section_enter();
elessair 0:f269e3021894 66 LPC_SCT3->CTRL |= (1 << 2);
elessair 0:f269e3021894 67 LPC_SCT3->MATCH0 = (uint32_t)timestamp;
elessair 0:f269e3021894 68 LPC_SCT3->CTRL &= ~(1 << 2);
elessair 0:f269e3021894 69 core_util_critical_section_exit();
elessair 0:f269e3021894 70
elessair 0:f269e3021894 71 // Enable interrupt on SCT3 event 0
elessair 0:f269e3021894 72 LPC_SCT3->EVEN = (1 << 0);
elessair 0:f269e3021894 73 }
elessair 0:f269e3021894 74
elessair 0:f269e3021894 75 void us_ticker_disable_interrupt(void) {
elessair 0:f269e3021894 76 // Disable interrupt on SCT3 event 0
elessair 0:f269e3021894 77 LPC_SCT3->EVEN = 0;
elessair 0:f269e3021894 78 }
elessair 0:f269e3021894 79
elessair 0:f269e3021894 80 void us_ticker_clear_interrupt(void) {
elessair 0:f269e3021894 81 // Clear SCT3 event 0 interrupt flag
elessair 0:f269e3021894 82 LPC_SCT3->EVFLAG = (1 << 0);
elessair 0:f269e3021894 83 }