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102 lines
3.0 KiB
102 lines
3.0 KiB
/* |
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* Copyright (C) 2014 INRIA |
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* |
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* This file is subject to the terms and conditions of the GNU Lesser |
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* General Public License v2.1. See the file LICENSE in the top level |
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* directory for more details. |
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*/ |
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/** |
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* @ingroup cpu |
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* @{ |
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* |
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* @file hwtimer_msp430_.c |
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* @brief MSP430x16xx timer functions |
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* |
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* @author Oliver Hahm <oliver.hahm@inria.fr> |
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* @author Milan Babel <babel@inf.fu-berlin.de> |
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* @author Kévin Roussel <Kevin.Roussel@inria.fr> |
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* |
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* @} |
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*/ |
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#include "cpu.h" |
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#include "hwtimer.h" |
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#include "arch/hwtimer_arch.h" |
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#define ENABLE_DEBUG (0) |
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#include "debug.h" |
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extern void (*int_handler)(int); |
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extern void timer_unset(short timer); |
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extern volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1]; |
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extern volatile uint16_t timer_round; |
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void timerA_init(void) |
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{ |
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volatile unsigned int *ccr; |
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volatile unsigned int *ctl; |
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timer_round = 0; /* Set to round 0 */ |
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TACTL = TASSEL_1 + TACLR; /* Clear the timer counter, set ACLK */ |
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TACTL &= ~TAIFG; /* Clear the IFG */ |
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TACTL |= TAIE; /* Enable TAIE (overflow IRQ) */ |
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for (int i = 0; i < HWTIMER_MAXTIMERS; i++) { |
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ccr = &TACCR0 + (i); |
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ctl = &TACCTL0 + (i); |
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*ccr = 0; |
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*ctl &= ~(CCIFG); |
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*ctl &= ~(CCIE); |
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} |
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TACTL |= MC_2; |
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} |
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interrupt(TIMERA0_VECTOR) __attribute__((naked)) timer_isr_ccr0(void) |
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{ |
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__enter_isr(); |
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if (overflow_interrupt[0] == timer_round) { |
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timer_unset(0); |
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int_handler(0); |
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} |
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__exit_isr(); |
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} |
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interrupt(TIMERA1_VECTOR) __attribute__((naked)) timer_isr(void) |
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{ |
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__enter_isr(); |
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short taiv_reg = TAIV; |
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if (taiv_reg == 0x0A) { |
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/* TAIV = 0x0A means overflow */ |
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DEBUG("Overflow\n"); |
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timer_round++; |
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} |
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else { |
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short timer = taiv_reg >> 1; |
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/* check which CCR has been hit and if the overflow counter |
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for this timer has been reached (or exceeded); |
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there is indeed a race condition where an hwtimer |
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due to fire in the next round can be set after |
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the timer's counter has overflowed but *before* |
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timer_round incrementation has occured (when |
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interrupts are disabled for any reason), thus |
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effectively setting the timer one round in the past! */ |
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int16_t round_delta = overflow_interrupt[timer] - timer_round; |
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/* in order to correctly handle timer_round overflow, |
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we must fire the timer when, for example, |
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timer_round == 0 and overflow_interrupt[timer] == 65535; |
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to that end, we compute the difference between the two |
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on a 16-bit signed integer: any difference >= +32768 will |
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thus overload to a negative number; we should then |
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correctly fire "overdue" timers whenever the case */ |
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if (round_delta <= 0) { |
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timer_unset(timer); |
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int_handler(timer); |
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} |
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} |
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__exit_isr(); |
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}
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