Merge pull request #5443 from dhalbert/time.monotonic-doc

Add precision info to time.monotonic() documentation

Author: dhalbert

locale/circuitpython.pot

@@ -1900,10 +1900,13 @@ msgid ""
 msgstr ""
 
 #: ports/raspberrypi/common-hal/imagecapture/ParallelImageCapture.c
-#: ports/raspberrypi/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Pins must be sequential"
 msgstr ""
 
+#: ports/raspberrypi/common-hal/rotaryio/IncrementalEncoder.c
+msgid "Pins must be sequential GPIO pins"
+msgstr ""
+
 #: ports/raspberrypi/common-hal/audiopwmio/PWMAudioOut.c
 msgid "Pins must share PWM slice"
 msgstr ""
@@ -3943,6 +3946,7 @@ msgstr ""
 #: ports/espressif/boards/adafruit_funhouse/mpconfigboard.h
 #: ports/espressif/boards/adafruit_magtag_2.9_grayscale/mpconfigboard.h
 #: ports/espressif/boards/adafruit_metro_esp32s2/mpconfigboard.h
+#: ports/espressif/boards/ai_thinker_esp32-c3s/mpconfigboard.h
 #: ports/espressif/boards/ai_thinker_esp_12k_nodemcu/mpconfigboard.h
 #: ports/espressif/boards/artisense_rd00/mpconfigboard.h
 #: ports/espressif/boards/atmegazero_esp32s2/mpconfigboard.h
@@ -3961,6 +3965,7 @@ msgstr ""
 #: ports/espressif/boards/gravitech_cucumber_rs/mpconfigboard.h
 #: ports/espressif/boards/lilygo_ttgo_t8_s2_st7789/mpconfigboard.h
 #: ports/espressif/boards/lolin_s2_mini/mpconfigboard.h
+#: ports/espressif/boards/microdev_micro_c3/mpconfigboard.h
 #: ports/espressif/boards/microdev_micro_s2/mpconfigboard.h
 #: ports/espressif/boards/morpheans_morphesp-240/mpconfigboard.h
 #: ports/espressif/boards/muselab_nanoesp32_s2_wroom/mpconfigboard.h

ports/raspberrypi/common-hal/rotaryio/IncrementalEncoder.c

@@ -68,7 +68,7 @@ void common_hal_rotaryio_incrementalencoder_construct(rotaryio_incrementalencode
         pins[1] = MP_OBJ_FROM_PTR(pin_a);
         self->swapped = false;
         if (!common_hal_rp2pio_pins_are_sequential(2, pins)) {
-            mp_raise_RuntimeError(translate("Pins must be sequential"));
+            mp_raise_RuntimeError(translate("Pins must be sequential GPIO pins"));
         }
     }
 

shared-bindings/time/__init__.c

@@ -39,12 +39,26 @@
 //| """time and timing related functions
 //|
 //| The `time` module is a strict subset of the CPython `cpython:time` module. So, code
-//| written in MicroPython will work in CPython but not necessarily the other
+//| using `time` written in CircuitPython will work in CPython but not necessarily the other
 //| way around."""
 //|
 //| def monotonic() -> float:
 //|     """Returns an always increasing value of time with an unknown reference
-//|     point. Only use it to compare against other values from `monotonic`.
+//|     point. Only use it to compare against other values from `time.monotonic()`.
+//|
+//|     On most boards, `time.monotonic()` converts a 64-bit millisecond tick counter
+//|     to a float. Floats on most boards are encoded in 30 bits internally, with
+//|     effectively 22 bits of precision. The float returned by `time.monotonic()` will
+//|     accurately represent time to millisecond precision only up to 2**22 milliseconds
+//|     (about 1.165 hours).
+//|     At that point it will start losing precision, and its value will change only
+//|     every second millisecond. At 2**23 milliseconds it will change every fourth
+//|     millisecond, and so forth.
+//|
+//|     If you need more consistent precision, use `time.monotonic_ns()`, or `supervisor.ticks_ms()`.
+//|     `time.monotonic_ns()` is not available on boards without long integer support.
+//|     `supervisor.ticks_ms()` uses intervals of a millisecond, but wraps around, and is not
+//|     CPython-compatible.
 //|
 //|     :return: the current monotonic time
 //|     :rtype: float"""
@@ -216,7 +230,8 @@ STATIC mp_obj_t time_time(void) {
 MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
 
 //| def monotonic_ns() -> int:
-//|     """Return the time of the monotonic clock, cannot go backward, in nanoseconds.
+//|     """Return the time of the monotonic clock, which cannot go backward, in nanoseconds.
+//|     Not available on boards without long integer support.
 //|
 //|     :return: the current time
 //|     :rtype: int"""