Ken Todotani / mbed-src

mbed library sources

Fork of mbed-src by mbed official

targets/hal/TARGET_NXP/TARGET_LPC408X/us_ticker.c@304:89b9c3a9a045, 2014-08-29 (annotated)

Committer:
mbed_official
Date:
Fri Aug 29 17:15:07 2014 +0100
Revision:
304:89b9c3a9a045
Parent:
15:4892fe388435 
Synchronized with git revision 734f365d7da26ef199751f4b0d91611479b495ea



Full URL: https://github.com/mbedmicro/mbed/commit/734f365d7da26ef199751f4b0d91611479b495ea/



1. timestamp_t as an abstraction for time values managed by

   Ticker. Using uint64_t for timestamp_t allows a wraparound-free

   Ticker. This change forces us to update the definitions of usTicker

   for all platforms; but the changes beyond nRF51822 aren't major.



2. reduce power consumption on the nRF51822 by removing the need for

   the high-frequency processor timer; and reimplementing it using the

   RTC.



I've also replaced high-frequency clock with low-frequency external

clock during system startup of the nRF51822. This brings a major win

in power consumption.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 15:4892fe388435 1 /* mbed Microcontroller Library
bogdanm 15:4892fe388435 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 15:4892fe388435 3 *
bogdanm 15:4892fe388435 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 15:4892fe388435 5 * you may not use this file except in compliance with the License.
bogdanm 15:4892fe388435 6 * You may obtain a copy of the License at
bogdanm 15:4892fe388435 7 *
bogdanm 15:4892fe388435 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 15:4892fe388435 9 *
bogdanm 15:4892fe388435 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 15:4892fe388435 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 15:4892fe388435 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 15:4892fe388435 13 * See the License for the specific language governing permissions and
bogdanm 15:4892fe388435 14 * limitations under the License.
bogdanm 15:4892fe388435 15 */
bogdanm 15:4892fe388435 16 #include <stddef.h>
bogdanm 15:4892fe388435 17 #include "us_ticker_api.h"
bogdanm 15:4892fe388435 18 #include "PeripheralNames.h"
bogdanm 15:4892fe388435 19
bogdanm 15:4892fe388435 20 #define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM3_BASE)
bogdanm 15:4892fe388435 21 #define US_TICKER_TIMER_IRQn TIMER3_IRQn
bogdanm 15:4892fe388435 22
bogdanm 15:4892fe388435 23 int us_ticker_inited = 0;
bogdanm 15:4892fe388435 24
bogdanm 15:4892fe388435 25 void us_ticker_init(void) {
bogdanm 15:4892fe388435 26 if (us_ticker_inited) return;
bogdanm 15:4892fe388435 27 us_ticker_inited = 1;
bogdanm 15:4892fe388435 28
bogdanm 15:4892fe388435 29 LPC_SC->PCONP |= 1 << 23; // Clock TIMER_3
bogdanm 15:4892fe388435 30
bogdanm 15:4892fe388435 31 US_TICKER_TIMER->CTCR = 0x0; // timer mode
bogdanm 15:4892fe388435 32 uint32_t PCLK = PeripheralClock;
bogdanm 15:4892fe388435 33
bogdanm 15:4892fe388435 34 US_TICKER_TIMER->TCR = 0x2; // reset
bogdanm 15:4892fe388435 35
bogdanm 15:4892fe388435 36 uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
bogdanm 15:4892fe388435 37 US_TICKER_TIMER->PR = prescale - 1;
bogdanm 15:4892fe388435 38 US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
bogdanm 15:4892fe388435 39
bogdanm 15:4892fe388435 40 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
bogdanm 15:4892fe388435 41 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
bogdanm 15:4892fe388435 42 }
bogdanm 15:4892fe388435 43
bogdanm 15:4892fe388435 44 uint32_t us_ticker_read() {
bogdanm 15:4892fe388435 45 if (!us_ticker_inited)
bogdanm 15:4892fe388435 46 us_ticker_init();
bogdanm 15:4892fe388435 47
bogdanm 15:4892fe388435 48 return US_TICKER_TIMER->TC;
bogdanm 15:4892fe388435 49 }
bogdanm 15:4892fe388435 50
mbed_official 304:89b9c3a9a045 51 void us_ticker_set_interrupt(timestamp_t timestamp) {
bogdanm 15:4892fe388435 52 // set match value
mbed_official 304:89b9c3a9a045 53 US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
bogdanm 15:4892fe388435 54 // enable match interrupt
bogdanm 15:4892fe388435 55 US_TICKER_TIMER->MCR |= 1;
bogdanm 15:4892fe388435 56 }
bogdanm 15:4892fe388435 57
bogdanm 15:4892fe388435 58 void us_ticker_disable_interrupt(void) {
bogdanm 15:4892fe388435 59 US_TICKER_TIMER->MCR &= ~1;
bogdanm 15:4892fe388435 60 }
bogdanm 15:4892fe388435 61
bogdanm 15:4892fe388435 62 void us_ticker_clear_interrupt(void) {
bogdanm 15:4892fe388435 63 US_TICKER_TIMER->IR = 1;
bogdanm 15:4892fe388435 64 }