STM32L0, L4, F7 and few F4 chip are supporting LPTIM feature.
We propose to allow user to use LPTIM for MBED LowPowerTimer API instead of using RTC wakeup timers.
By default, all targets that are supporting this feature have been configured.
Add RSF synchro during init
Set a better WakeUp clock for long wake up period in order to stay in sleep mode
Use rtc_isenabled function before init as rtc_init is called at each set_time call
lp_ticker driver is the known registered user of RTC handler API.
In case, a lp_ticker is set in the past, the lp_ticker_fire_interrupt
will be called which itself sets the RTC interrupt as pending by calling
NVIC_SetPendingIRQ(RTC_WKUP_IRQn). This all happens without actual
programing of the RTC wake-up.
As a result the RTC HW and corresponding HAL layer doesn't expect an
interrupt to happen and will not call HAL_RTCEx_WakeUpTimerEventCallback.
To sove this situation, we will not use HAL_RTCEx_WakeUpTimerEventCallback
weak definition but rather call handler whenever an RTC interrupt fires.
The use of mktime was causing a fault when called in interrupt handler because on GCC it lock the mutex protecting the environment, To overcome this issue, this patch add dedicated routine to convert a time_t into a tm and vice versa.
In the process mktime has been optimized and is now an order of magnitude faster than the routines present in the C library.
jeromecoutant
Jimmy Brisson
Laurent MEUNIER
bcostm
Sam Grove
Vincent Coubard