Umar Naeem / mbed-dev

mbed library sources. Supersedes mbed-src.

Fork of mbed-dev by Umar Naeem

targets/TARGET_NXP/TARGET_LPC15XX/us_ticker.c@165:2dd56e6daeec, 2017-05-23 (annotated)

Committer:
ranaumarnaeem
Date:
Tue May 23 12:54:50 2017 +0000
Revision:
165:2dd56e6daeec
Parent:
160:d5399cc887bb 
jhjg

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #include <stddef.h>
<> 144:ef7eb2e8f9f7 17 #include "us_ticker_api.h"
<> 144:ef7eb2e8f9f7 18 #include "PeripheralNames.h"
<> 160:d5399cc887bb 19 #include "mbed_critical.h"
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 #define US_TICKER_TIMER_IRQn SCT3_IRQn
<> 144:ef7eb2e8f9f7 22
<> 144:ef7eb2e8f9f7 23 int us_ticker_inited = 0;
<> 144:ef7eb2e8f9f7 24
<> 144:ef7eb2e8f9f7 25 void us_ticker_init(void) {
<> 144:ef7eb2e8f9f7 26 if (us_ticker_inited)
<> 144:ef7eb2e8f9f7 27 return;
<> 144:ef7eb2e8f9f7 28
<> 144:ef7eb2e8f9f7 29 us_ticker_inited = 1;
<> 144:ef7eb2e8f9f7 30
<> 144:ef7eb2e8f9f7 31 // Enable the SCT3 clock
<> 144:ef7eb2e8f9f7 32 LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << 5);
<> 144:ef7eb2e8f9f7 33
<> 144:ef7eb2e8f9f7 34 // Clear peripheral reset the SCT3
<> 144:ef7eb2e8f9f7 35 LPC_SYSCON->PRESETCTRL1 |= (1 << 5);
<> 144:ef7eb2e8f9f7 36 LPC_SYSCON->PRESETCTRL1 &= ~(1 << 5);
<> 144:ef7eb2e8f9f7 37
<> 144:ef7eb2e8f9f7 38 // Configure SCT3 as a 1MHz 32-bit counter with no auto limiting or match reload
<> 144:ef7eb2e8f9f7 39 char sctClkDiv = ((SystemCoreClock + 1000000 - 1) / 1000000) - 1;
<> 144:ef7eb2e8f9f7 40 LPC_SCT3->CONFIG = (1 << 7) | (1 << 0);
<> 144:ef7eb2e8f9f7 41 LPC_SCT3->CTRL = (sctClkDiv << 5) | (1 << 3) | (1 << 2);
<> 144:ef7eb2e8f9f7 42
<> 144:ef7eb2e8f9f7 43 // Configure SCT3 event 0 to fire on match register 0
<> 144:ef7eb2e8f9f7 44 LPC_SCT3->EV0_STATE = (1 << 0);
<> 144:ef7eb2e8f9f7 45 LPC_SCT3->EV0_CTRL = (0x1 << 12);
<> 144:ef7eb2e8f9f7 46
<> 144:ef7eb2e8f9f7 47 // Start SCT3
<> 144:ef7eb2e8f9f7 48 LPC_SCT3->CTRL &= ~(1 << 2);
<> 144:ef7eb2e8f9f7 49
<> 144:ef7eb2e8f9f7 50 // Set SCT3 interrupt vector
<> 144:ef7eb2e8f9f7 51 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
<> 144:ef7eb2e8f9f7 52 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 53 }
<> 144:ef7eb2e8f9f7 54
<> 144:ef7eb2e8f9f7 55 uint32_t us_ticker_read() {
<> 144:ef7eb2e8f9f7 56 if (!us_ticker_inited)
<> 144:ef7eb2e8f9f7 57 us_ticker_init();
<> 144:ef7eb2e8f9f7 58
<> 144:ef7eb2e8f9f7 59 // Return SCT3 count value
<> 144:ef7eb2e8f9f7 60 return LPC_SCT3->COUNT;
<> 144:ef7eb2e8f9f7 61 }
<> 144:ef7eb2e8f9f7 62
<> 144:ef7eb2e8f9f7 63 void us_ticker_set_interrupt(timestamp_t timestamp) {
<> 144:ef7eb2e8f9f7 64 // Set SCT3 match register 0 (critical section)
<> 144:ef7eb2e8f9f7 65 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 66 LPC_SCT3->CTRL |= (1 << 2);
<> 144:ef7eb2e8f9f7 67 LPC_SCT3->MATCH0 = (uint32_t)timestamp;
<> 144:ef7eb2e8f9f7 68 LPC_SCT3->CTRL &= ~(1 << 2);
<> 144:ef7eb2e8f9f7 69 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 70
<> 144:ef7eb2e8f9f7 71 // Enable interrupt on SCT3 event 0
<> 144:ef7eb2e8f9f7 72 LPC_SCT3->EVEN = (1 << 0);
<> 144:ef7eb2e8f9f7 73 }
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 void us_ticker_disable_interrupt(void) {
<> 144:ef7eb2e8f9f7 76 // Disable interrupt on SCT3 event 0
<> 144:ef7eb2e8f9f7 77 LPC_SCT3->EVEN = 0;
<> 144:ef7eb2e8f9f7 78 }
<> 144:ef7eb2e8f9f7 79
<> 144:ef7eb2e8f9f7 80 void us_ticker_clear_interrupt(void) {
<> 144:ef7eb2e8f9f7 81 // Clear SCT3 event 0 interrupt flag
<> 144:ef7eb2e8f9f7 82 LPC_SCT3->EVFLAG = (1 << 0);
<> 144:ef7eb2e8f9f7 83 }