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/* mbed Microcontroller Library
* Copyright (c) 2006-2013 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stddef.h>
#include "us_ticker_api.h"
#include "PeripheralNames.h"
#define US_TICKER_TIMER TIM2
#define US_TICKER_TIMER_IRQn TIM2_IRQn
int us_ticker_inited = 0;
void us_ticker_init(void) {
if (us_ticker_inited) return;
us_ticker_inited = 1;
RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
uint32_t PCLK = SystemCoreClock / 4;
uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
US_TICKER_TIMER->PSC = prescale - 1;
US_TICKER_TIMER->CR1 |= TIM_CR1_CEN;
// Trigger an update - this needs to happen after the counter is enabled.
US_TICKER_TIMER->EGR |= TIM_EGR_UG;
NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
}
uint32_t us_ticker_read() {
if (!us_ticker_inited)
us_ticker_init();
return US_TICKER_TIMER->CNT;
}
void us_ticker_set_interrupt(timestamp_t timestamp) {
// set match value
US_TICKER_TIMER->CCR1 = (uint32_t)timestamp;
// enable compare interrupt
US_TICKER_TIMER->DIER |= TIM_DIER_CC1IE;
}
void us_ticker_disable_interrupt(void) {
US_TICKER_TIMER->DIER &= ~TIM_DIER_CC1IE;
}
void us_ticker_clear_interrupt(void) {
US_TICKER_TIMER->SR &= ~TIM_SR_CC1IF;
}
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