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STM32F1: Correct timer master value reading #3076

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Merged
merged 1 commit into from
Oct 26, 2016
Merged

STM32F1: Correct timer master value reading #3076

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5 changes: 2 additions & 3 deletions targets/TARGET_STM/TARGET_STM32F1/TARGET_BLUEPILL_F103C8/device/hal_tick.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,10 +43,9 @@ void set_compare(uint16_t count);
extern volatile uint32_t SlaveCounter;
extern volatile uint32_t oc_int_part;
extern volatile uint16_t oc_rem_part;
extern volatile uint16_t cnt_val;

void timer_irq_handler(void) {
cnt_val = TIM_MST->CNT;
uint16_t cval = TIM_MST->CNT;

TimMasterHandle.Instance = TIM_MST;

Expand All @@ -68,7 +67,7 @@ void timer_irq_handler(void) {
} else {
if (oc_int_part > 0) {
set_compare(0xFFFF);
oc_rem_part = cnt_val; // To finish the counter loop the next time
oc_rem_part = cval; // To finish the counter loop the next time
oc_int_part--;
} else {
us_ticker_irq_handler();
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5 changes: 2 additions & 3 deletions targets/TARGET_STM/TARGET_STM32F1/TARGET_NUCLEO_F103RB/device/hal_tick.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,10 +43,9 @@ void set_compare(uint16_t count);
extern volatile uint32_t SlaveCounter;
extern volatile uint32_t oc_int_part;
extern volatile uint16_t oc_rem_part;
extern volatile uint16_t cnt_val;

void timer_irq_handler(void) {
cnt_val = TIM_MST->CNT;
uint16_t cval = TIM_MST->CNT;

TimMasterHandle.Instance = TIM_MST;

Expand All @@ -68,7 +67,7 @@ void timer_irq_handler(void) {
} else {
if (oc_int_part > 0) {
set_compare(0xFFFF);
oc_rem_part = cnt_val; // To finish the counter loop the next time
oc_rem_part = cval; // To finish the counter loop the next time
oc_int_part--;
} else {
us_ticker_irq_handler();
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24 changes: 16 additions & 8 deletions targets/TARGET_STM/TARGET_STM32F1/us_ticker.c
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,6 @@ 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;
volatile uint16_t cnt_val = 0;

void set_compare(uint16_t count)
{
Expand All @@ -59,15 +58,24 @@ void us_ticker_init(void)

uint32_t us_ticker_read()
{
uint32_t counter;
uint32_t counter, counter2;
if (!us_ticker_inited) us_ticker_init();

//Current value of TIM_MST->CNT is stored in cnt_val and is
//updated in interrupt context
// 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 += cnt_val;

return counter;
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)
Expand Down