mbed RTC specifications now dictate that the RTC needs to retain and keep on counting through reset. On Silicon Labs parts, this means the RTC API can not be backed by the Silicon Labs RTC peripheral, since that doesn't provide retention functionality.
Therefore:
* On EFM32GG, EFM32WG, EFM32LG: mbed RTC API is now backed by BURTC.
* On EFM32PG, EFR32MG, EFM32PG12, EFR32MG12: mbed RTC API is now backed by RTCC.
* On EFM32ZG, EFM32HG: mbed RTC API is sadly no longer supported, since these chips don't have retained memory.
I implemented the RTC feature.
The mainly changing is here.
- rtc_init()
Previously, I have initialized the time information register in the function, so the time count was cleaned by every calling rtc_init().
Currently, rtc_init() doesn't stop RTC from counting, and rtc_init() is safe to call repeatedly.
Therefore in order to satisfy specifications,I removed the initialization process of the time information register in the function.
- rtc_free()
Previously, I have initialized the RTC related register same as rtc_init(), so the time count was cleaned by calling rtc_free().
Currently, rtc_free() doesn't stop RTC from counting.
Therefore in order to satisfy specifications,I removed the process and decided not to do anything in the function.
If powerdown the RTC, Supply of the clock to the RTC is stopped, cannot keeping the count.
Make rtc_isenabled() to return 1 if the RTC is initialized and the time has been set; 0 otherwise.
Disable clock gate on exit from this function if RTC was initialized.
Keep the RTC code if either DEVICE_RTC or DEVICE_LOWPOWERTIMER is
defined on the devices which use the RTC for both the rtc api and the
low power timer api. This allows DEVICE_LOWPOWERTIMER to be enabled while
DEVICE_RTC is turned off.
- Disable microsecond ticker interrupt on reinitialization
- Skip us_ticker_set_interrupt() if timestamp is already past
- Eliminate tmr2Config since tmrConfig is adequate for all timer config
1. Enable LPTICKER for K22, K24, K64, K66, K82, KL82F, KW24D
2. Change the implementation to only use the LPTMR which reduces
the amount of interrupts generated which is required for tickless
operation
Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>
I decided to move these files to the targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_NRF51 since us_ticker.h is for sure specific for NRF51_DK and common_rtc.c might be valid also for NRF52, but this needs to be checked while porting NRF52_DK board.
Provide the following modifications for lp ticker driver:
- According to NRF51_DK reference manual rtc interrupt cannot be controlled by rtc event. In the previous implementation interrupts were enabled permanently and specific interrupt was enabled/disabled by enabling/disabling the specific event. If event is enabled, then event signal is provided to Programmable Peripheral Interconnect (PPI). If interrupt is enabled, then interrupt signal is provided to Nested Vector Interrupt Controller (NVIC). Disable all events permanently. Enable lp ticker overflow interrupt permanently(needed for RTC), disable lp ticker capture/compare interrupt on init (lp_ticker_init) , enable lp ticker interrupt when lp ticker interrupt is set (lp_ticker_set_interrupt), disable lp ticker interrupt on disable request(lp_ticker_disable_interrupt).
- Provide lp ticker data for higher level (freq: 32kHz / len: 24 bits),
- Add the following features to init routine: disable lp ticker interrupt.
- Make ticker driver to operate on ticks instead of us.
- Simplify lp ticker read and set interrupt routines (upper layers handle conversion to us and interrupt scheduling).
Martin Kojtal
Bartek Szatkowski
Edmund Hsu
Mahesh Mahadevan
Steven Cooreman
TomoYamanaka
Przemyslaw Stekiel
Russ Butler
Ashok Rao
Jesse Marroquin