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Improve us ticker performance 

Improves accuracy during heavy work load.
pull/6364/head
Keyur Hariya 2018-02-02 10:55:49 -06:00 committed by Cruz Monrreal II
parent ab00b4641b
commit 58b8439cad
1 changed files with 24 additions and 4 deletions
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28
targets/TARGET_Maxim/TARGET_MAX32625/us_ticker.c
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@ -33,9 +33,11 @@
#include <stddef.h>
#include "mbed_error.h"
#include "mbed_critical.h"
#include "us_ticker_api.h"
#include "PeripheralNames.h"
#include "tmr.h"
#include "assert.h"
#define US_TIMER MXC_TMR0
#define US_TIMER_IRQn TMR0_0_IRQn
@ -49,7 +51,7 @@ static volatile uint64_t event_cnt; // Holds the value of the next event
#define MAX_TICK_VAL ((uint64_t)0xFFFFFFFF * ticks_per_us)
//******************************************************************************
static inline void inc_current_cnt(uint32_t inc)
static inline void inc_current_cnt_no_crit(uint32_t inc)
{
// Overflow the ticker when the us ticker overflows
current_cnt += inc;
@ -58,6 +60,14 @@ static inline void inc_current_cnt(uint32_t inc)
}
}
//******************************************************************************
static inline void inc_current_cnt(uint32_t inc)
{
core_util_critical_section_enter();
inc_current_cnt_no_crit(inc);
core_util_critical_section_exit();
}
//******************************************************************************
static inline int event_passed(uint64_t current, uint64_t event)
{
@ -89,11 +99,12 @@ static void tmr_handler(void)
{
uint32_t cmp = TMR32_GetCompare(US_TIMER);
TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); // reset to max value to prevent further interrupts
if (TMR32_GetFlag(US_TIMER)) {
inc_current_cnt_no_crit(cmp);
}
TMR32_ClearFlag(US_TIMER);
NVIC_ClearPendingIRQ(US_TIMER_IRQn);
inc_current_cnt(cmp);
if (event_passed(current_cnt + TMR32_GetCount(US_TIMER), event_cnt)) {
// the timestamp has expired
event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
@ -162,6 +173,7 @@ uint32_t us_ticker_read(void)
uint64_t current_cnt1, current_cnt2;
uint32_t cmp, cnt;
uint32_t flag1, flag2;
static uint32_t last = 0;
if (!us_ticker_inited) {
us_ticker_init();
@ -179,12 +191,19 @@ uint32_t us_ticker_read(void)
// Account for an unserviced interrupt
if (flag1) {
// Clear peripheral interrupt flag; leaving NVIC pending set
TMR32_ClearFlag(US_TIMER);
// Advance global count
inc_current_cnt(cmp + cnt);
current_cnt1 += cmp;
}
current_cnt1 += cnt;
return (current_cnt1 / ticks_per_us);
assert(last <= (current_cnt1 / ticks_per_us));
last = (current_cnt1 / ticks_per_us);
return last;
}
//******************************************************************************
@ -228,6 +247,7 @@ void us_ticker_set_interrupt(timestamp_t timestamp)
TMR32_Start(US_TIMER);
}
//******************************************************************************
void us_ticker_fire_interrupt(void)
{
TMR32_SetCompare(US_TIMER, 1);