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Improved accuracy for microsecond delays

pull/2274/head
Bogdan Marinescu 2016-08-08 19:04:38 +03:00
parent 1a1507ac78
commit 49606cd5de
1 changed files with 4 additions and 10 deletions
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14
hal/common/mbed_wait_api_rtos.cpp
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@ -31,16 +31,8 @@ void wait_ms(int ms) {
wait_us(ms * 1000); wait_us(ms * 1000);
} }
// Wait for the given number of microseconds using a hardware timer
// in a busy wait loop
static void wait_us_busy(int us) {
if (us > 0) {
uint32_t start = us_ticker_read();
while ((us_ticker_read() - start) < (uint32_t)us);
}
}
void wait_us(int us) { void wait_us(int us) {
uint32_t start = us_ticker_read();
// Use the RTOS to wait for millisecond delays if possible // Use the RTOS to wait for millisecond delays if possible
int ms = us / 1000; int ms = us / 1000;
if ((ms > 0) && core_util_are_interrupts_enabled()) { if ((ms > 0) && core_util_are_interrupts_enabled()) {
@ -49,7 +41,9 @@ void wait_us(int us) {
} }
// Use busy waiting for sub-millisecond delays, or for the whole // Use busy waiting for sub-millisecond delays, or for the whole
// interval if interrupts are not enabled // interval if interrupts are not enabled
wait_us_busy(us); if (us > 0) {
while((us_ticker_read() - start) < (uint32_t)us);
}
} }
#endif // #if MBED_CONF_RTOS_PRESENT #endif // #if MBED_CONF_RTOS_PRESENT