Ken Todotani / mbed-src

mbed library sources

Fork of mbed-src by mbed official

targets/hal/TARGET_NXP/TARGET_LPC11UXX/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:
13:0645d8841f51 
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
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
emilmont 10:3bc89ef62ce7 20 #define US_TICKER_TIMER ((LPC_CTxxBx_Type *)LPC_CT32B1_BASE)
emilmont 10:3bc89ef62ce7 21 #define US_TICKER_TIMER_IRQn TIMER_32_1_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_SYSCON->SYSAHBCLKCTRL |= (1<<10); // Clock TIMER_1
emilmont 10:3bc89ef62ce7 30 uint32_t PCLK = SystemCoreClock;
emilmont 10:3bc89ef62ce7 31
emilmont 10:3bc89ef62ce7 32 US_TICKER_TIMER->TCR = 0x2; // reset
emilmont 10:3bc89ef62ce7 33
emilmont 10:3bc89ef62ce7 34 uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
emilmont 10:3bc89ef62ce7 35 US_TICKER_TIMER->PR = prescale - 1;
emilmont 10:3bc89ef62ce7 36 US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
emilmont 10:3bc89ef62ce7 37
emilmont 10:3bc89ef62ce7 38 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
emilmont 10:3bc89ef62ce7 39 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
emilmont 10:3bc89ef62ce7 40 }
emilmont 10:3bc89ef62ce7 41
emilmont 10:3bc89ef62ce7 42 uint32_t us_ticker_read() {
emilmont 10:3bc89ef62ce7 43 if (!us_ticker_inited)
emilmont 10:3bc89ef62ce7 44 us_ticker_init();
emilmont 10:3bc89ef62ce7 45
emilmont 10:3bc89ef62ce7 46 return US_TICKER_TIMER->TC;
emilmont 10:3bc89ef62ce7 47 }
emilmont 10:3bc89ef62ce7 48
mbed_official 304:89b9c3a9a045 49 void us_ticker_set_interrupt(timestamp_t timestamp) {
emilmont 10:3bc89ef62ce7 50 // set match value
mbed_official 304:89b9c3a9a045 51 US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
emilmont 10:3bc89ef62ce7 52 // enable match interrupt
emilmont 10:3bc89ef62ce7 53 US_TICKER_TIMER->MCR |= 1;
emilmont 10:3bc89ef62ce7 54 }
emilmont 10:3bc89ef62ce7 55
emilmont 10:3bc89ef62ce7 56 void us_ticker_disable_interrupt(void) {
emilmont 10:3bc89ef62ce7 57 US_TICKER_TIMER->MCR &= ~1;
emilmont 10:3bc89ef62ce7 58 }
emilmont 10:3bc89ef62ce7 59
emilmont 10:3bc89ef62ce7 60 void us_ticker_clear_interrupt(void) {
emilmont 10:3bc89ef62ce7 61 US_TICKER_TIMER->IR = 1;
emilmont 10:3bc89ef62ce7 62 }