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Make hwtimer_spin() work even with interrupts disabled

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by using only 16 significative bits on MSP430 hardware timers
dev/timer
Kévin Roussel 9 years ago
parent 5c9d749649
commit d101b30dd8
4 changed files with 22 additions and 81 deletions
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45
cpu/cc430/hwtimer_cc430.c
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@ -31,17 +31,15 @@
extern void (*int_handler)(int);
extern void timer_unset(short timer);
extern volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
extern volatile uint16_t timer_round;
void timerA_init(void)
{
volatile unsigned int *ccr = &TA0CCR0;
volatile unsigned int *ctl = &TA0CCTL0;
timer_round = 0; /* Set to round 0 */
TA0CTL = TASSEL_1 + TACLR; /* Clear the timer counter, set ACLK */
TA0CTL &= ~TAIFG; /* Clear the IFG */
TA0CTL |= TAIE; /* Enable TAIE (overflow IRQ) */
TA0CTL &= ~TAIE; /* Disable TAIE (overflow IRQ) */
for (int i = 0; i < HWTIMER_MAXTIMERS; i++) {
*(ccr + i) = 0;
@ -56,10 +54,8 @@ interrupt(TIMER0_A0_VECTOR) __attribute__((naked)) timer0_a0_isr(void)
{
__enter_isr();
if (overflow_interrupt[0] == timer_round) {
timer_unset(0);
int_handler(0);
}
timer_unset(0);
int_handler(0);
__exit_isr();
}
@ -68,35 +64,10 @@ interrupt(TIMER0_A1_VECTOR) __attribute__((naked)) timer0_a1_5_isr(void)
{
__enter_isr();
short taiv_reg = TA0IV;
if (taiv_reg == 0x0E) {
/* TAIV = 0x0E means overflow */
DEBUG("Overflow\n");
timer_round++;
}
else {
short timer = taiv_reg >> 1;
/* check which CCR has been hit and if the overflow counter
for this timer has been reached (or exceeded);
there is indeed a race condition where an hwtimer
due to fire in the next round can be set after
the timer's counter has overflowed but *before*
timer_round incrementation has occured (when
interrupts are disabled for any reason), thus
effectively setting the timer one round in the past! */
int16_t round_delta = overflow_interrupt[timer] - timer_round;
/* in order to correctly handle timer_round overflow,
we must fire the timer when, for example,
timer_round == 0 and overflow_interrupt[timer] == 65535;
to that end, we compute the difference between the two
on a 16-bit signed integer: any difference >= +32768 will
thus overload to a negative number; we should then
correctly fire "overdue" timers whenever the case */
if (round_delta <= 0) {
timer_unset(timer);
int_handler(timer);
}
}
/* determine which CCR has been hit, and fire the appropriate callback */
short timer = TA0IV >> 1;
timer_unset(timer);
int_handler(timer);
__exit_isr();
}

5
cpu/msp430-common/hwtimer_cpu.c
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@ -18,8 +18,6 @@
void (*int_handler)(int);
extern void timerA_init(void);
volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
volatile uint16_t timer_round;
#ifdef CC430
/* CC430 have "TimerA0", "TimerA1" and so on... */
@ -55,7 +53,6 @@ static void timer_set_nostart(uint32_t value, short timer)
if (value <= hwtimer_arch_now()) {
value = hwtimer_arch_now() + 2;
}
overflow_interrupt[timer] = (uint16_t)(value >> 16);
*ptr = (value & 0xFFFF);
}
@ -75,7 +72,7 @@ void timer_unset(short timer)
unsigned long hwtimer_arch_now(void)
{
return ((uint32_t)timer_round << 16) + TIMER_VAL_REG;
return (TIMER_VAL_REG & 0xffff);
}
void hwtimer_arch_init(void (*handler)(int), uint32_t fcpu)

2
cpu/msp430-common/include/hwtimer_cpu.h
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@ -34,7 +34,7 @@ extern "C" {
#endif
#define HWTIMER_SPEED (F_RC_OSCILLATOR)
#define HWTIMER_MAXTICKS (0xFFFFFFFF)
#define HWTIMER_MAXTICKS (0x0000FFFF)
#ifdef __cplusplus
}

51
cpu/msp430fxyz/hwtimer_msp430.c
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@ -29,19 +29,19 @@
extern void (*int_handler)(int);
extern void timer_unset(short timer);
extern volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
extern volatile uint16_t timer_round;
void timerA_init(void)
{
timer_round = 0; /* Set to round 0 */
volatile unsigned int *ccr;
volatile unsigned int *ctl;
TACTL = TASSEL_1 + TACLR; /* Clear the timer counter, set ACLK */
TACTL &= ~TAIFG; /* Clear the IFG */
TACTL |= TAIE; /* Enable TAIE (overflow IRQ) */
TACTL &= ~TAIE; /* Disable TAIE (overflow IRQ) */
for (int i = 0; i < HWTIMER_MAXTIMERS; i++) {
volatile unsigned int *ccr = &TACCR0 + (i);
volatile unsigned int *ctl = &TACCTL0 + (i);
ccr = &TACCR0 + (i);
ctl = &TACCTL0 + (i);
*ccr = 0;
*ctl &= ~(CCIFG);
*ctl &= ~(CCIE);
@ -54,10 +54,8 @@ interrupt(TIMERA0_VECTOR) __attribute__((naked)) timer_isr_ccr0(void)
{
__enter_isr();
if (overflow_interrupt[0] == timer_round) {
timer_unset(0);
int_handler(0);
}
timer_unset(0);
int_handler(0);
__exit_isr();
}
@ -66,35 +64,10 @@ interrupt(TIMERA1_VECTOR) __attribute__((naked)) timer_isr(void)
{
__enter_isr();
short taiv_reg = TAIV;
if (taiv_reg == 0x0A) {
/* TAIV = 0x0A means overflow */
DEBUG("Overflow\n");
timer_round++;
}
else {
short timer = taiv_reg >> 1;
/* check which CCR has been hit and if the overflow counter
for this timer has been reached (or exceeded);
there is indeed a race condition where an hwtimer
due to fire in the next round can be set after
the timer's counter has overflowed but *before*
timer_round incrementation has occured (when
interrupts are disabled for any reason), thus
effectively setting the timer one round in the past! */
int16_t round_delta = overflow_interrupt[timer] - timer_round;
/* in order to correctly handle timer_round overflow,
we must fire the timer when, for example,
timer_round == 0 and overflow_interrupt[timer] == 65535;
to that end, we compute the difference between the two
on a 16-bit signed integer: any difference >= +32768 will
thus overload to a negative number; we should then
correctly fire "overdue" timers whenever the case */
if (round_delta <= 0) {
timer_unset(timer);
int_handler(timer);
}
}
/* determine which CCR has been hit, and fire the appropriate callback */
short timer = TAIV >> 1;
timer_unset(timer);
int_handler(timer);
__exit_isr();
}

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