mirror of https://github.com/ARMmbed/mbed-os.git
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2013 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stddef.h>
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#include "us_ticker_api.h"
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#include "PeripheralNames.h"
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const ticker_info_t* us_ticker_get_info()
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{
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static const ticker_info_t info = {
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1000000, // 1 MHz
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32 // 32 bit counter
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};
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return &info;
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}
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static bool us_ticker_inited = false;
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#if MBED_CONF_TARGET_US_TICKER_TIMER == 0
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#define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM0_BASE)
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#define US_TICKER_TIMER_IRQn TIMER0_IRQn
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#elif MBED_CONF_TARGET_US_TICKER_TIMER == 1
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#define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM1_BASE)
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#define US_TICKER_TIMER_IRQn TIMER1_IRQn
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#elif MBED_CONF_TARGET_US_TICKER_TIMER == 2
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#define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM2_BASE)
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#define US_TICKER_TIMER_IRQn TIMER2_IRQn
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#else
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#define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM3_BASE)
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#define US_TICKER_TIMER_IRQn TIMER3_IRQn
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#endif
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void us_ticker_init(void) {
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if (us_ticker_inited) {
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/* calling init again should cancel current interrupt */
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us_ticker_disable_interrupt();
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return;
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}
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us_ticker_inited = true;
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LPC_SC->PCONP |= 1 << 23; // Clock TIMER_3
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US_TICKER_TIMER->CTCR = 0x0; // timer mode
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uint32_t PCLK = SystemCoreClock / 4;
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US_TICKER_TIMER->TCR = 0x2; // reset
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uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
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US_TICKER_TIMER->PR = prescale - 1;
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US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
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NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
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NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
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}
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uint32_t us_ticker_read() {
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return US_TICKER_TIMER->TC;
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}
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void us_ticker_set_interrupt(timestamp_t timestamp) {
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// set match value
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US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
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// enable match interrupt
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US_TICKER_TIMER->MCR |= 1;
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}
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void us_ticker_fire_interrupt(void)
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{
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NVIC_SetPendingIRQ(US_TICKER_TIMER_IRQn);
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}
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void us_ticker_disable_interrupt(void) {
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US_TICKER_TIMER->MCR &= ~1;
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}
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void us_ticker_clear_interrupt(void) {
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US_TICKER_TIMER->IR = 1;
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}
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void us_ticker_free(void)
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{
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US_TICKER_TIMER->TCR = 0;
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US_TICKER_TIMER->MCR &= ~1;
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NVIC_DisableIRQ(US_TICKER_TIMER_IRQn);
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}
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