Intelligent Systems / mbed-src

This fork of the MBED Library allows you to use counters on the external counter pins (15/16 for Timer 3, 29/30 for Timer 2) by switching internal timing functions in MBED to utilize Timer 0

Fork of mbed-src by mbed official

targets/hal/TARGET_NXP/TARGET_LPC176X/us_ticker.c@349:591ef4b19797, 2014-10-23 (annotated)

Committer:
bparrott
Date:
Thu Oct 23 10:10:42 2014 +0000
Revision:
349:591ef4b19797
Parent:
304:89b9c3a9a045 
This changes the timer used at the core of MBED from Timer 3 to Timer 0. This allows for the use of external pins with both Timer 2 and 3.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 10:3bc89ef62ce7 1 /* mbed Microcontroller Library
emilmont 10:3bc89ef62ce7 2 * Copyright (c) 2006-2013 ARM Limited
emilmont 10:3bc89ef62ce7 3 *
emilmont 10:3bc89ef62ce7 4 * Licensed under the Apache License, Version 2.0 (the "License");
emilmont 10:3bc89ef62ce7 5 * you may not use this file except in compliance with the License.
emilmont 10:3bc89ef62ce7 6 * You may obtain a copy of the License at
emilmont 10:3bc89ef62ce7 7 *
emilmont 10:3bc89ef62ce7 8 * http://www.apache.org/licenses/LICENSE-2.0
emilmont 10:3bc89ef62ce7 9 *
emilmont 10:3bc89ef62ce7 10 * Unless required by applicable law or agreed to in writing, software
emilmont 10:3bc89ef62ce7 11 * distributed under the License is distributed on an "AS IS" BASIS,
emilmont 10:3bc89ef62ce7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
emilmont 10:3bc89ef62ce7 13 * See the License for the specific language governing permissions and
emilmont 10:3bc89ef62ce7 14 * limitations under the License.
emilmont 10:3bc89ef62ce7 15 */
emilmont 10:3bc89ef62ce7 16 #include <stddef.h>
emilmont 10:3bc89ef62ce7 17 #include "us_ticker_api.h"
emilmont 10:3bc89ef62ce7 18 #include "PeripheralNames.h"
emilmont 10:3bc89ef62ce7 19
bparrott 349:591ef4b19797 20 #define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM0_BASE)
bparrott 349:591ef4b19797 21 #define US_TICKER_TIMER_IRQn TIMER0_IRQn
emilmont 10:3bc89ef62ce7 22
emilmont 10:3bc89ef62ce7 23 int us_ticker_inited = 0;
emilmont 10:3bc89ef62ce7 24
emilmont 10:3bc89ef62ce7 25 void us_ticker_init(void) {
emilmont 10:3bc89ef62ce7 26 if (us_ticker_inited) return;
emilmont 10:3bc89ef62ce7 27 us_ticker_inited = 1;
emilmont 10:3bc89ef62ce7 28
emilmont 10:3bc89ef62ce7 29 LPC_SC->PCONP |= 1 << 23; // Clock TIMER_3
emilmont 10:3bc89ef62ce7 30
emilmont 10:3bc89ef62ce7 31 US_TICKER_TIMER->CTCR = 0x0; // timer mode
emilmont 10:3bc89ef62ce7 32 uint32_t PCLK = SystemCoreClock / 4;
emilmont 10:3bc89ef62ce7 33
emilmont 10:3bc89ef62ce7 34 US_TICKER_TIMER->TCR = 0x2; // reset
emilmont 10:3bc89ef62ce7 35
emilmont 10:3bc89ef62ce7 36 uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
emilmont 10:3bc89ef62ce7 37 US_TICKER_TIMER->PR = prescale - 1;
emilmont 10:3bc89ef62ce7 38 US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
emilmont 10:3bc89ef62ce7 39
emilmont 10:3bc89ef62ce7 40 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
emilmont 10:3bc89ef62ce7 41 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
emilmont 10:3bc89ef62ce7 42 }
emilmont 10:3bc89ef62ce7 43
emilmont 10:3bc89ef62ce7 44 uint32_t us_ticker_read() {
emilmont 10:3bc89ef62ce7 45 if (!us_ticker_inited)
emilmont 10:3bc89ef62ce7 46 us_ticker_init();
emilmont 10:3bc89ef62ce7 47
emilmont 10:3bc89ef62ce7 48 return US_TICKER_TIMER->TC;
emilmont 10:3bc89ef62ce7 49 }
emilmont 10:3bc89ef62ce7 50
mbed_official 304:89b9c3a9a045 51 void us_ticker_set_interrupt(timestamp_t timestamp) {
emilmont 10:3bc89ef62ce7 52 // set match value
mbed_official 304:89b9c3a9a045 53 US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
emilmont 10:3bc89ef62ce7 54 // enable match interrupt
emilmont 10:3bc89ef62ce7 55 US_TICKER_TIMER->MCR |= 1;
emilmont 10:3bc89ef62ce7 56 }
emilmont 10:3bc89ef62ce7 57
emilmont 10:3bc89ef62ce7 58 void us_ticker_disable_interrupt(void) {
emilmont 10:3bc89ef62ce7 59 US_TICKER_TIMER->MCR &= ~1;
emilmont 10:3bc89ef62ce7 60 }
emilmont 10:3bc89ef62ce7 61
emilmont 10:3bc89ef62ce7 62 void us_ticker_clear_interrupt(void) {
emilmont 10:3bc89ef62ce7 63 US_TICKER_TIMER->IR = 1;
emilmont 10:3bc89ef62ce7 64 }