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Superseded
This library was superseded by mbed-dev - https://os.mbed.com/users/mbed_official/code/mbed-dev/.
Development branch of the mbed library sources. This library is kept in synch with the latest changes from the mbed SDK and it is not guaranteed to work.
If you are looking for a stable and tested release, please import one of the official mbed library releases:
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The official Mbed 2 C/C++ SDK provides the software platform and libraries to build your applications.
targets/hal/TARGET_Maxim/TARGET_MAX32610/us_ticker.c
- Committer:
- mbed_official
- Date:
- 2015-07-06
- Revision:
- 583:967d0d8b7aed
- Parent:
- 536:c48d7048ab6e
File content as of revision 583:967d0d8b7aed:
/******************************************************************************* * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Except as contained in this notice, the name of Maxim Integrated * Products, Inc. shall not be used except as stated in the Maxim Integrated * Products, Inc. Branding Policy. * * The mere transfer of this software does not imply any licenses * of trade secrets, proprietary technology, copyrights, patents, * trademarks, maskwork rights, or any other form of intellectual * property whatsoever. Maxim Integrated Products, Inc. retains all * ownership rights. ******************************************************************************* */ #include "mbed_error.h" #include "us_ticker_api.h" #include "PeripheralNames.h" #include "tmr_regs.h" #define US_TIMER MXC_TMR0 #define US_TIMER_IRQn TMR0_IRQn static int us_ticker_inited = 0; static uint32_t ticks_per_us; static uint32_t tick_win; static volatile uint64_t current_cnt; // Hold the current ticks static volatile uint64_t event_cnt; // Holds the value of the next event #define ticks_to_us(ticks) ((ticks) / ticks_per_us); #define MAX_TICK_VAL ((uint64_t)0xFFFFFFFF * ticks_per_us) //****************************************************************************** static inline void inc_current_cnt(uint32_t inc) { // Overflow the ticker when the us ticker overflows current_cnt += inc; if (current_cnt > MAX_TICK_VAL) { current_cnt -= (MAX_TICK_VAL + 1); } } //****************************************************************************** static inline int event_passed(uint64_t current, uint64_t event) { // Determine if the event has already happened. // If the event is behind the current ticker, within a window, // then the event has already happened. if (((current < tick_win) && ((event < current) || (event > (MAX_TICK_VAL - (tick_win - current))))) || ((event < current) && (event > (current - tick_win)))) { return 1; } return 0; } //****************************************************************************** static inline uint64_t event_diff(uint64_t current, uint64_t event) { // Check to see if the ticker will overflow before the event if(current <= event) { return (event - current); } return ((MAX_TICK_VAL - current) + event); } //****************************************************************************** static void tmr_handler(void) { uint32_t term_cnt32 = US_TIMER->term_cnt32; US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt NVIC_ClearPendingIRQ(US_TIMER_IRQn); inc_current_cnt(term_cnt32); if (event_passed(current_cnt + US_TIMER->count32, event_cnt )) { // the timestamp has expired event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value us_ticker_irq_handler(); } else { uint64_t diff = event_diff(current_cnt, event_cnt); if (diff < (uint64_t)0xFFFFFFFF) { // the event occurs before the next overflow US_TIMER->term_cnt32 = diff; // Since the timer keeps counting after the terminal value is reached, it is possible that the new // terminal value is in the past. if (US_TIMER->term_cnt32 < US_TIMER->count32) { // the timestamp has expired US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt NVIC_ClearPendingIRQ(US_TIMER_IRQn); event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value us_ticker_irq_handler(); } } } } //****************************************************************************** void us_ticker_init(void) { if (us_ticker_inited) return; us_ticker_inited = 1; current_cnt = 0; event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value if (SystemCoreClock <= 1000000) { error("us_ticker cannot operate at this SystemCoreClock"); return; } // Configure timer for 32-bit continuous mode with /1 prescaler US_TIMER->ctrl = MXC_E_TMR_MODE_CONTINUOUS << MXC_F_TMR_CTRL_MODE_POS | (0 << MXC_F_TMR_CTRL_PRESCALE_POS); ticks_per_us = SystemCoreClock / 1000000; // Set the tick window to 10ms tick_win = SystemCoreClock/100; // Set timer overflow to the max US_TIMER->term_cnt32 = 0xFFFFFFFF; US_TIMER->pwm_cap32 = 0xFFFFFFFF; US_TIMER->count32 = 0; US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear pending interrupts NVIC_SetVector(US_TIMER_IRQn, (uint32_t)tmr_handler); NVIC_EnableIRQ(US_TIMER_IRQn); US_TIMER->inten |= MXC_F_TMR_INTEN_TIMER0; // enable interrupts US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer } //****************************************************************************** void us_ticker_deinit(void) { US_TIMER->ctrl = 0; // disable timer US_TIMER->inten = 0; // disable interrupts US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupts us_ticker_inited = 0; } //****************************************************************************** uint32_t us_ticker_read(void) { uint64_t current_cnt1, current_cnt2; uint32_t term_cnt, tmr_cnt; uint32_t intfl1, intfl2; if (!us_ticker_inited) us_ticker_init(); // Ensure coherency between current_cnt and US_TIMER->count32 do { current_cnt1 = current_cnt; intfl1 = US_TIMER->intfl; term_cnt = US_TIMER->term_cnt32; tmr_cnt = US_TIMER->count32; intfl2 = US_TIMER->intfl; current_cnt2 = current_cnt; } while ((current_cnt1 != current_cnt2) || (intfl1 != intfl2)); // Account for an unserviced interrupt if (intfl1) { current_cnt1 += term_cnt; } current_cnt1 += tmr_cnt; return (current_cnt1 / ticks_per_us); } //****************************************************************************** void us_ticker_set_interrupt(timestamp_t timestamp) { // Note: interrupts are disabled before this function is called. US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer if (US_TIMER->intfl) { US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt NVIC_ClearPendingIRQ(US_TIMER_IRQn); inc_current_cnt(US_TIMER->term_cnt32); } // add and reset the current count value inc_current_cnt(US_TIMER->count32); US_TIMER->count32 = 0; // add the number of cycles that the timer is disabled here for inc_current_cnt(200); event_cnt = (uint64_t)timestamp * ticks_per_us; // Check to see if the event has already passed if (!event_passed(current_cnt, event_cnt)) { uint64_t diff = event_diff(current_cnt, event_cnt); if (diff < (uint64_t)0xFFFFFFFF) { // the event occurs before the next overflow US_TIMER->term_cnt32 = diff; } else { // the event occurs after the next overflow US_TIMER->term_cnt32 = 0xFFFFFFFF; // set to max } } else { // the requested timestamp occurs in the past // set the timer up to immediately expire US_TIMER->term_cnt32 = 1; } US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer } //****************************************************************************** void us_ticker_disable_interrupt(void) { // There are no more events, set timer overflow to the max US_TIMER->term_cnt32 = 0xFFFFFFFF; } //****************************************************************************** void us_ticker_clear_interrupt(void) { // cleared in the local handler } //****************************************************************************** void us_ticker_set(timestamp_t timestamp) { US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer current_cnt = (uint64_t)timestamp * ticks_per_us; US_TIMER->count32 = 0; US_TIMER->term_cnt32 = 0xFFFFFFFF; US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer if (((uint64_t)timestamp * ticks_per_us) >= event_cnt) { // The next timestamp has elapsed. Trigger the interrupt to handle it. NVIC_SetPendingIRQ(US_TIMER_IRQn); } }