kopia lustrzana https://github.com/peterhinch/micropython-samples
astronomy: Update docs and code.
Peter Hinch
rodzic
baf4251274
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b3f27dfae0
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@ -7,6 +7,7 @@
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2. [The RiSet class](./README.md#2-the-riset-class)
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2.1 [Constructor](./README.md#21-constructor)
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2.2 [Methods](./README.md#22-methods)
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2.3 [Effect of local time](./README.md#23-effect-of-local-time)
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3. [The moonphase function](./README.md#3-the-moonphase-function)
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4. [Utility functions](./README.md#4-utility-functions)
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5. [Demo script](./README.md#5-demo-script)
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@ -94,7 +95,8 @@ rise or set event.
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Args (float):
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* `lat=LAT` Latitude in degrees (-ve is South). Defaults are my location. :)
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* `long=LONG` Longitude in degrees (-ve is West).
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* `lto=0` Local time offset in hours to UTC (-ve is West).
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* `lto=0` Local time offset in hours to UTC (-ve is West); the value is checked
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to ensure `-12 < lto < 12`. See [section 2.3](./README.md#23-effect-of-local-time).
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## 2.2 Methods
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@ -114,6 +116,7 @@ moon, 0.5 is full. See [section 3](./README.md#3-the-moonphase-function) for
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observations about this.
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* `set_lto(t)` Set localtime offset in hours relative to UTC. Primarily intended
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for daylight saving time. Rise and set times are updated if the lto is changed.
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The value is checked to ensure `-12 < lto < 12`. See [section 2.3](./README.md#23-effect-of-local-time).
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The return value of the rise and set method is determined by the `variant` arg.
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In all cases rise and set events are identified which occur in the current 24
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@ -132,6 +135,27 @@ r = RiSet() # UK near Manchester
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r = RiSet(lat=47.609722, long=-122.3306, lto=-8) # Seattle 47°36′35″N 122°19′59″W
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r = RiSet(lat=-33.87667, long=151.21, lto=11) # Sydney 33°52′04″S 151°12′36″E
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```
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## 2.3 Effect of local time
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MicroPython has no concept of local time. A hardware platform has a clock;
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depending on application this might be permanently set to local winter time, or
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it might be adjusted twice per year for local daylight saving time. It is the
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responsibility of the application to do this if it is considered necessary.
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Rise and set times are computed relative to UTC and then adjusted using the
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`RiSet` instance's local time offset before being returned (see `.adjust()`).
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This applies to all variants - note that the local platform epoch is on a fixed
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date at 00:00:00 local time.
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If the machine clock has a fixed relationship to UTC, `RiSet` instances should
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have a corresponding fixed local time offset: rise and set times will be
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relative to that time. If the application implements daylight saving time, the
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local time offsets should be adjusted accordingly.
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The constructor and the `set_day()` method set the instance's date relative to
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the machine clock. They use only the date component of system time, hence they
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may be run at any time of day. In continuously-running applications, `set_day()`
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may be run each day just after midnight to keep a `RiSet` instance up to date.
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# 3. The moonphase function
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@ -203,22 +227,31 @@ Code comments show times retrieved from `timeanddate.com`.
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# 6. Scheduling events
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A likely use case is to enable events to be timed relative to sunrise and set.
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In simple cases this can be done with `asyncio`. This routine, called before
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sunrise, will perform some action at dawn and quit:
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In simple cases this can be done with `asyncio`. This coroutine will execute a
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payload at sunrise every day. A similar coroutine might handle sunsets.
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```python
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from sched.sun_moon import RiSet
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import uasyncio as asyncio
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import time
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rs = RiSet()
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async def wait_for_sunrise():
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tsecs = time.time() % 86400 # Time now in secs since midnight
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rs.set_day() # Ensure today's date
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twait = rs.sunrise() - tsecs # Time before Sunrise
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if twait > 0: # Sunrise has not yet occurred
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await asyncio.sleep(twait)
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# Turn the lights off, or whatever
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from sched.sun_moon import RiSet
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async def tomorrow(): # Wait until 1 minute past midnight
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now = round(time.time())
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tw = 86400 + 60 - (now % 86400) # Time from now to one minute past next midnight
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await asyncio.sleep(tw)
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async def do_sunrise():
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rs = RiSet() # May need args
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while True:
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if (now := round(time.time())) < rs.sunrise(1): # Sun has not yet risen
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await asyncio.sleep(rs.sunrise(1) - now) # Wait for it to rise
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# Sun has risen, execute payload
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await tomorrow()
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rs.set_day() # Update to new day
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```
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The problem with the above is ensuring that `wait_for_sunrise` is called shortly
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after midnight. A simple solution is to use the
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This code assumes that `.sunrise()` will never return `None`. At polar latitudes
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waiting for sunrise in winter would require changes.
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Code may be simplified by using the
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[schedule module](https://github.com/peterhinch/micropython-async/blob/master/v3/docs/SCHEDULE.md).
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This may be installed with
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```bash
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@ -23,6 +23,10 @@ LONG = -2.102811634540558
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# (date(2000, 1, 1) - date(1970, 1, 1)).days = 10957
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# Return time now in days relative to platform epoch.
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# System time is set to local time, and MP has no concept of this. Hence
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# time.time() returns secs since epoch 00:00:00 local time. If lto is local time
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# offset to UTC, provided -12 < lto < 12, the effect of rounding ensures the
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# right number of days for platform epoch at UTC.
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def now_days() -> int:
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secs_per_day = 86400 # 24 * 3600
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t = time.time()
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@ -77,7 +81,7 @@ def quad(ym, yz, yp):
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# hence the MJD of an integer day number will always be an integer
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# Re platform comparisons get_mjd returns the same value regardless of
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# the platform's epoch: integer days since 00:00 on 17 November 1858.
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# the platform's epoch: integer days since 00:00 UTC on 17 November 1858.
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def get_mjd(ndays: int = 0) -> int:
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secs_per_day = 86400 # 24 * 3600
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days_from_epoch = now_days() + ndays # Days since platform epoch
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@ -198,6 +202,8 @@ class RiSet:
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self.sglat = sin(radians(lat))
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self.cglat = cos(radians(lat))
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self.long = long
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if not -12 < lto < 12:
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raise ValueError("Invalid local time offset.")
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self.lto = round(lto * 3600) # Localtime offset in secs
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self.mjd = None # Current integer MJD
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# Times in integer secs from midnight on current day (in local time)
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@ -237,23 +243,37 @@ class RiSet:
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def moonphase(self) -> float:
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return self._phase
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# May need to temporarily adjust self.mjd
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# def is_up(self, sun=True):
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# t = ((time.time() % 86400) + self.lto) / 3600
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# return sin_alt(t, sun) > 0
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def set_lto(self, t): # Update the offset from UTC
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if not -12 < t < 12:
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raise ValueError("Invalid local time offset.")
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lto = round(t * 3600) # Localtime offset in secs
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if self.lto != lto: # changed
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self.lto = lto
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self.update(self.mjd)
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def is_up(self, sun: bool): # Return current state of sun or moon
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t = time.time() + self.lto # UTC
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t %= 86400
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t /= 3600 # UTC Hour of day
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self.set_day() # Ensure today's date
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return self.sin_alt(t, sun) > 0
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now = round(time.time()) + self.lto # UTC
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rt = self.sunrise(1) if sun else self.moonrise(1)
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st = self.sunset(1) if sun else self.moonset(1)
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if rt is None:
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if st is None:
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t = (now % 86400) / 3600 # Time as UTC hours (float)
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return self.sin_alt(t, sun) > 0
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return st > now
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if st is None:
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return rt < now
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print(rt, now, st)
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return rt < now < st
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# This is in error by ~12 minutes: sin_alt() produces incorrect values
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# unless t corresponds to an exact hour. Odd.
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# def is_up(self, sun: bool):
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# t = time.time() + self.lto # UTC
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# t %= 86400
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# t /= 3600 # UTC Hour of day
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# self.set_day() # Ensure today's date
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# return self.sin_alt(t, sun) > 0
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# ***** API end *****
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# Re-calculate rise and set times
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