I implemented USTICKER feature.
The mainly changing is here.
- I added a macro to mbed_drv_cfg.h for commonalizing code for GR-PEACH and GR-LYCHEE with different clock frequencies, and referenced it's macro at us_ticker.c.
- ticker_init()
Currently, ticker_init() keep counting, disables the ticker interrupt, and is safe to call repeatedly.
Therefore, in order to satisfy specifications, I removed GIC_EnableIRQ at end of function and added GIC_DisableIRQ at begin of function.
When an interrupt is required, it will be set with ticker_set_interrupt().
If executing the following, the counter has been initialized. So it will not call after executing the first time.
OSTM1TT = 0x01; /* Stop the counter and clears the OSTM1TE bit. */
OSTM1TS = 0x1; /* Start the counter and sets the OSTM0TE bit. */
- ticker_free()
this function stops the counting and powerdown the us_ticker.
To satisfy the mbed specificationm, I implemented free() function.
- ticker_read()
Currently, Mbed spec's frequeny is between 250KHz and 8MHz, but the frequency that is used at my ticker is 33MHz.
Therefore, in order to satisfy specifications, I changed the process to return the timer counter value divided by 32(33MHz / 32).
Since the calcurate function by using 64 bit is no longer necessay, I removed it.
- ticker_set_interrupt()
Same as the above read(),
In order to satisfy specifications, I changed the process to set the value multiplied by 32.
- ticker_fire_interrupt()
In order to satisfy specifications, I implemented fire_interrupt() function.
Also I added GIC_EnableIRQ for allowing the interrupt at end of function.
- ticker_get_info()
To satisfy the mbed specificationm, I implemented ticker_get_info() function. The value of freq includes rounding off.
Update the ticker common test to clean up after each case by restoring
the ticker IRQ handler. This allows tickers to function normally after
each case has completed.
The new HAL allows to share the timer bit width and frequency,
the actual handling of mapping 16 bits counter up to 32 bits or
64 bits is now managed by mbed common layer.
This makes this ticker layer very similar to 32bits one and much
easier than before.
Re-implemented both us_ticker and lp_ticker to match the new API and specifications.
Details:
* On EFM32GG, EFM32WG, EFM32LG, EFM32HG, EFM32ZG: Use the RTC peripheral to back lp_ticker, and a TIMER to back us_ticker.
* On EFM32PG, EFR32MG, EFM32PG12, EFR32MG12: Use the RTCC peripheral to back lp_ticker (dual-purpose, also used to back RTC), and a TIMER to back us_ticker.
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.
# Conflicts:
# targets/TARGET_Silicon_Labs/TARGET_EFM32/lp_ticker.c
# targets/TARGET_Silicon_Labs/TARGET_EFM32/rtc_api.c
# targets/targets.json
- count_ticks: fix counter overflow handling,
- count_ticks: use reg_cycles variable in while loop,
- increment test: reduce number of cycles for slow cores if measure process needs to be repeated (difference is greater than 1).
On slow targets with fast high frequency tickers like NRF51_DK (16 Mhz CPU/1MHz ticker) time window for test case execution without overflow needs to be increased. Add parameter to `overflow_protect` function to be able to set different time window without overflow for us ticker and lp ticker.
Increment test proves that ticker counter is incremented by one.
This is done indirectly for high frequency counters where it is impossible to read 'value' and 'value + 1' in two successive ticker reads.
This check is done indirectly by counting ticker ticks elapsed during execution of N cycles of empty while loop. Unfortunately on slow boards with fast tickers like NRF51_DK(16 MHz CPU/1MHz hf ticker) it is possible that for the same N cycles measured number of elapsed ticks in two successive calls is greater than 1. This patch provides fix for such case - measure operation is repeated with the same number of cycles.
Since target specific ticker drivers are not ready also features which uses ticker in upper layers may not work correctly and tests for these features.
We need to disable also failing higher level ticker related tests (by adding check if DEVICE_USTICKER symbol is available and raise #error [NOT_SUPPORTED] if not).
Note:
tests-mbed_drivers-rtc is new and uses us ticker to perform a delay.
count_ticks() function counts ticker ticks elapsed during execution of N cycles of empty while loop.
In current version N value (cycles) is given as volatile paramater in order to disable possible compiler optimalisation.
There was a problem with measured time on different compilers and additionally results on ARM compiler were unexpected (the difference beetween measured elapsed ticks for the same number of cycles was to large). This might be caused by the memory access in order to store updated variable in memory. To fix this issue given numer of cycles has been stored into register and register is decremented (no memory access).
With this fix count_ticks(NUM_OF_CYCLES, 1) call returns 2500 +/-1 for us ticker ticks using each compiler (K64F).
On some platforms (e.g. K64F) different counters are used for time measurement and interrupt generation.
Because of that we should relax interrupt test case and give additional time before checking if interrupt handler has been executed.
Since according to the ticker requirements min acceptable counter size is 12 bits (low power timer) for which max count is 4095, then all test cases must be executed in this time window.
HAL ticker layer handles overflow and it is not handled in the target ticker drivers.
Low power ticker time counter is created based on RTC which is driven by 32KHz clock. Additional low power timer is used to generate interrupts.
We need to adapt driver to operate on ticks instead of us.
Perform the following updates:
- provide lp ticker configuration: 32KHz/32 bit counter.
- lp_ticker_init() routine disables lp ticker interrupts .
- adapt the driver functions to operate on ticks instead us.
- adapt comments.
- add us_ticker_free() routine.
The intention was to use ticker_overflow_delta equal to 0 for low power ticker tests and ticker_overflow_delta equal to 50 for high frequency ticker tests. Current implementation is invalid since for devices which provide LOW_POWER_TIMER feature delta is equal to 0 and for devices without this feature delta is equal 50.
Current version:
The function ticker_init resets the internal count and disables the ticker interrupt.
Proposed version:
The function ticker_init allows the ticker to keep counting and disables the ticker interrupt.
This is a result of the following discussion:
https://github.com/ARMmbed/mbed-os/pull/5233#pullrequestreview-86677815
Since target specific ticker drivers are not ready also features which uses ticker in upper layers may not work correctly and tests for these features.
We need to disable also failing higher level ticker related tests (by adding check if DEVICE_USTICKER symbol is available and raise #error [NOT_SUPPORTED] if not).
jeromecoutant
Bartek Szatkowski
TomoYamanaka
Przemyslaw Stekiel
Russ Butler
Laurent MEUNIER
Steven Cooreman
Steven Cartmell
Russ Butler