372306411a
I instrumented RTC_Handler and determined that on SAMD51 it was possible for the interrupt to be delivered well before the actual overflow of the RTC COUNT register (e.g., a value as small as 0xffff_fffd could be seen at the time of overflow) Rather than depending on the overflow interrupt coming in at the same time as COUNT overflows (exactly), rely only on observed values of COUNT in _get_count, overflowing when it wraps around from a high value to a low one. With this change, PLUS a second change so that it is possible to warp the RTC counter close to an overflow and test in 20ms instead of 3 days, there was no problem detected over 20000+ overflows. Before, a substantial fraction (much greater than 10%) of overflows failed. Fixes #5985 Change to common-hal/rtc/RTC.c for time warping (plus make rtc_old_count non-static): ```patch void common_hal_rtc_set_calibration(int calibration) { + + common_hal_mcu_disable_interrupts(); + + RTC->MODE0.COUNT.reg = 0xffffff00; + rtc_old_count = 0; + do { + while ((RTC->MODE0.SYNCBUSY.reg & (RTC_MODE0_SYNCBUSY_COUNTSYNC | RTC_MODE0_SYNCBUSY_COUNT)) != 0) { } + } + while(RTC->MODE0.COUNT.reg < 0xffffff00); + common_hal_mcu_enable_interrupts(); + + mp_printf(&mp_plat_print, "Warping RTC in calibration setter count=%08x rtc_old_count=%08x\n", RTC->MODE0.COUNT.reg, rtc_old_count); ``` Test program: ```python import time from rtc import RTC i = 0 while True: RTC().calibration = 1 # Warps to ~16ms before overflow, with patch to RTC code t0 = time.monotonic_ns() et = t0 + 20_000_000 # 20ms while (t1 := time.monotonic_ns()) < et: pass i += 1 print(f"{i:6d}: duration {t1-t0}") if t1-t0 > 200_000_000: break print() ``` |
||
|---|---|---|
| .. | ||
| asf4@84f56af132 | ||
| asf4_conf | ||
| bindings/samd | ||
| boards | ||
| common-hal | ||
| freetouch@b6859a349e | ||
| modules | ||
| peripherals@d3b20192cf | ||
| sd_mmc | ||
| supervisor | ||
| tools | ||
| .gitattributes | ||
| .gitignore | ||
| Makefile | ||
| README.rst | ||
| audio_dma.c | ||
| audio_dma.h | ||
| background.c | ||
| background.h | ||
| eic_handler.c | ||
| eic_handler.h | ||
| fatfs_port.c | ||
| ld_defines.c | ||
| mpconfigport.h | ||
| mpconfigport.mk | ||
| mphalport.c | ||
| mphalport.h | ||
| qstrdefsport.h | ||
| reset.c | ||
| reset.h | ||
| samd_peripherals_config.h | ||
| shared_timers.c | ||
| shared_timers.h | ||
| timer_handler.c | ||
| timer_handler.h | ||
README.rst
SAMD21 and SAMD51
==================
This port supports many development boards that utilize SAMD21 and SAMD51 chips. See
https://circuitpython.org/downloads for all supported boards.
Building
--------
For build instructions see this guide: https://learn.adafruit.com/building-circuitpython/
Debugging
---------
For debugging instructions see this guide: https://learn.adafruit.com/debugging-the-samd21-with-gdb
Port Specific modules
---------------------
.. toctree::
../../shared-bindings/samd/index