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/* mbed Microcontroller Library
* Copyright (c) 2014, STMicroelectronics
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stddef.h>
#include "us_ticker_api.h"
#include "PeripheralNames.h"
// Timer selection
#define TIM_MST TIM21
static TIM_HandleTypeDef TimMasterHandle;
static int us_ticker_inited = 0;
volatile uint32_t SlaveCounter = 0;
volatile uint32_t oc_int_part = 0;
volatile uint16_t oc_rem_part = 0;
void set_compare(uint16_t count)
{
TimMasterHandle.Instance = TIM_MST;
// Set new output compare value
__HAL_TIM_SetCompare(&TimMasterHandle, TIM_CHANNEL_1, count);
// Enable IT
__HAL_TIM_ENABLE_IT(&TimMasterHandle, TIM_IT_CC1);
}
void us_ticker_init(void)
{
if (us_ticker_inited) return;
us_ticker_inited = 1;
HAL_InitTick(0); // The passed value is not used
}
uint32_t us_ticker_read()
{
uint32_t counter, counter2;
if (!us_ticker_inited) us_ticker_init();
// A situation might appear when Master overflows right after Slave is read and before the
// new (overflowed) value of Master is read. Which would make the code below consider the
// previous (incorrect) value of Slave and the new value of Master, which would return a
// value in the past. Avoid this by computing consecutive values of the timer until they
// are properly ordered.
counter = (uint32_t)(SlaveCounter << 16);
counter += TIM_MST->CNT;
while (1) {
counter2 = (uint32_t)(SlaveCounter << 16);
counter2 += TIM_MST->CNT;
if (counter2 > counter) {
break;
}
counter = counter2;
}
return counter2;
}
void us_ticker_set_interrupt(timestamp_t timestamp)
{
int delta = (int)((uint32_t)timestamp - us_ticker_read());
uint16_t cval = TIM_MST->CNT;
if (delta <= 0) { // This event was in the past
us_ticker_irq_handler();
} else {
oc_int_part = (uint32_t)(delta >> 16);
oc_rem_part = (uint16_t)(delta & 0xFFFF);
if (oc_rem_part <= (0xFFFF - cval)) {
set_compare(cval + oc_rem_part);
oc_rem_part = 0;
} else {
set_compare(0xFFFF);
oc_rem_part = oc_rem_part - (0xFFFF - cval);
}
}
}
void us_ticker_disable_interrupt(void)
{
TimMasterHandle.Instance = TIM_MST;
__HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
}
void us_ticker_clear_interrupt(void)
{
TimMasterHandle.Instance = TIM_MST;
if (__HAL_TIM_GET_FLAG(&TimMasterHandle, TIM_FLAG_CC1) == SET) {
__HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
}
}
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