diff --git a/cpu/cc430/hwtimer_cc430.c b/cpu/cc430/hwtimer_cc430.c
index 466ca500bae5dd9ecd936a580176a7b4d716ccf6..75d6f6bed668d5e99e2bfbffbe026d374060a18d 100644
--- a/cpu/cc430/hwtimer_cc430.c
+++ b/cpu/cc430/hwtimer_cc430.c
@@ -27,18 +27,16 @@
#define ENABLE_DEBUG (0)
#include "debug.h"
-static uint32_t ticks = 0;
extern void (*int_handler)(int);
extern void timer_unset(short timer);
-extern uint16_t overflow_interrupt[HWTIMER:_MAXTIMERS+1];
-extern uint16_t timer_round;
+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;
- ticks = 0; /* Set tick counter value to 0 */
timer_round = 0; /* Set to round 0 */
TA0CTL = TASSEL_1 + TACLR; /* Clear the timer counter, set ACLK */
TA0CTL &= ~TAIFG; /* Clear the IFG */
@@ -56,10 +54,12 @@ void timerA_init(void)
interrupt(TIMER0_A0_VECTOR) __attribute__((naked)) timer0_a0_isr(void)
{
__enter_isr();
+
if (overflow_interrupt[0] == timer_round) {
timer_unset(0);
int_handler(0);
}
+
__exit_isr();
}
@@ -67,18 +67,34 @@ interrupt(TIMER0_A1_VECTOR) __attribute__((naked)) timer0_a1_5_isr(void)
{
__enter_isr();
- short taiv = TA0IV;
- short timer = taiv / 2;
- /* TAIV = 0x0E means overflow */
- if (taiv == 0x0E) {
+ short taiv_reg = TA0IV;
+ if (taiv_reg == 0x0E) {
+ /* TAIV = 0x0E means overflow */
DEBUG("Overflow\n");
- timer_round += 1;
+ timer_round++;
}
- /* check which CCR has been hit and if the overflow counter for this timer
- * has been reached */
- else if (overflow_interrupt[timer] == timer_round) {
- timer_unset(timer);
- int_handler(timer);
+ 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);
+ }
}
__exit_isr();
diff --git a/cpu/msp430-common/hwtimer_cpu.c b/cpu/msp430-common/hwtimer_cpu.c
index de561ff24bc77f4d913bb7827e9d9f86d52bbea5..f9cd892bc8c370cd21e7836b3866d7e7800d42dc 100644
--- a/cpu/msp430-common/hwtimer_cpu.c
+++ b/cpu/msp430-common/hwtimer_cpu.c
@@ -22,8 +22,8 @@ See the file LICENSE in the top level directory for more details.
void (*int_handler)(int);
extern void timerA_init(void);
-uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
-uint16_t timer_round;
+volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
+volatile uint16_t timer_round;
#ifdef CC430
/* CC430 have "TimerA0", "TimerA1" and so on... */
@@ -52,15 +52,20 @@ static void timer_enable_interrupt(short timer)
*ptr &= ~(CCIFG);
}
-static void timer_set_nostart(unsigned long value, short timer)
+static void timer_set_nostart(uint32_t value, short timer)
{
volatile unsigned int *ptr = &CNT_COMP_BASE_REG + (timer);
- *ptr = value;
+ /* ensure we won't set the timer to a "past" tick */
+ if (value <= hwtimer_arch_now()) {
+ value = hwtimer_arch_now() + 2;
+ }
+ overflow_interrupt[timer] = (uint16_t)(value >> 16);
+ *ptr = (value & 0xFFFF);
}
-static void timer_set(unsigned long value, short timer)
+static void timer_set(uint32_t value, short timer)
{
- DEBUG("Setting timer %u to %u overflows and %lu\n", timer, overflow_interrupt[timer], value);
+ DEBUG("Setting timer %u to %lu\n", timer, value);
timer_set_nostart(value, timer);
timer_enable_interrupt(timer);
}
@@ -74,7 +79,7 @@ void timer_unset(short timer)
unsigned long hwtimer_arch_now()
{
- return ((uint32_t)timer_round << 16)+TIMER_VAL_REG;
+ return ((uint32_t)timer_round << 16) + TIMER_VAL_REG;
}
void hwtimer_arch_init(void (*handler)(int), uint32_t fcpu)
@@ -106,9 +111,7 @@ void hwtimer_arch_set(unsigned long offset, short timer)
void hwtimer_arch_set_absolute(unsigned long value, short timer)
{
- uint16_t small_value = value & 0xFFFF;
- overflow_interrupt[timer] = (uint16_t)(value >> 16);
- timer_set(small_value, timer);
+ timer_set(value, timer);
}
void hwtimer_arch_unset(short timer)
diff --git a/cpu/msp430x16x/hwtimer_msp430.c b/cpu/msp430x16x/hwtimer_msp430.c
index aa55b05662ed3386ce1411e8f3a51f70b851c8e0..8c15ad90a326d8d6732b72d5b159a20996dd7b82 100644
--- a/cpu/msp430x16x/hwtimer_msp430.c
+++ b/cpu/msp430x16x/hwtimer_msp430.c
@@ -27,18 +27,15 @@
#define ENABLE_DEBUG (0)
#include "debug.h"
-static uint32_t ticks = 0;
-
extern void (*int_handler)(int);
extern void timer_unset(short timer);
-extern uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
-extern uint16_t timer_round;
+extern volatile uint16_t overflow_interrupt[HWTIMER_MAXTIMERS+1];
+extern volatile uint16_t timer_round;
void timerA_init(void)
{
volatile unsigned int *ccr;
volatile unsigned int *ctl;
- ticks = 0; /* Set tick counter value to 0 */
timer_round = 0; /* Set to round 0 */
TACTL = TASSEL_1 + TACLR; /* Clear the timer counter, set ACLK */
TACTL &= ~TAIFG; /* Clear the IFG */
@@ -58,10 +55,12 @@ void timerA_init(void)
interrupt(TIMERA0_VECTOR) __attribute__((naked)) timer_isr_ccr0(void)
{
__enter_isr();
+
if (overflow_interrupt[0] == timer_round) {
timer_unset(0);
int_handler(0);
}
+
__exit_isr();
}
@@ -69,18 +68,34 @@ interrupt(TIMERA1_VECTOR) __attribute__((naked)) timer_isr(void)
{
__enter_isr();
- short taiv = TAIV;
- short timer = taiv / 2;
- /* TAIV = 0x0A means overflow */
- if (taiv == 0x0A) {
+ short taiv_reg = TAIV;
+ if (taiv_reg == 0x0A) {
+ /* TAIV = 0x0A means overflow */
DEBUG("Overflow\n");
- timer_round += 1;
+ timer_round++;
}
- /* check which CCR has been hit and if the overflow counter for this timer
- * has been reached */
- else if (overflow_interrupt[timer] == timer_round) {
- timer_unset(timer);
- int_handler(timer);
+ 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);
+ }
}
__exit_isr();