kopia lustrzana https://github.com/peterhinch/micropython-samples
Delta now returns mS. Cal delays in minutes, default 5.
rodzic
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@ -1,6 +1,7 @@
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# Pyboard driver for DS3231 precison real time clock.
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# Adapted from WiPy driver at https://github.com/scudderfish/uDS3231
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# Includes routine to calibrate the Pyboard's RTC from the DS3231
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# delta method now operates to 1mS precision
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# Adapted by Peter Hinch, Jan 2016
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import utime, pyb
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@ -24,9 +25,8 @@ def bcd2dec(bcd):
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return (((bcd & 0xf0) >> 4) * 10 + (bcd & 0x0f))
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def dec2bcd(dec):
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t = dec // 10
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o = dec - t * 10
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return (t << 4) + o
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tens, units = divmod(dec, 10)
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return (tens << 4) + units
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class DS3231:
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def __init__(self, side = 'X'):
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@ -43,7 +43,7 @@ class DS3231:
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def get_time(self, set_rtc = False):
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if set_rtc:
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data = self.await_transition() # For accuracy set RTC immediately after a seconds transition
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data = self.await_transition() # For accuracy set RTC immediately after a seconds transition
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else:
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data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0) # don't wait
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ss = bcd2dec(data[0])
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@ -80,38 +80,46 @@ class DS3231:
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self.ds3231.mem_write(dec2bcd(MM), DS3231_I2C_ADDR, 5)
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self.ds3231.mem_write(dec2bcd(YY-1900), DS3231_I2C_ADDR, 6)
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def delta(self):
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return utime.time() - utime.mktime(self.get_time()) # No. of secs RTC leads DS3231
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def delta(self): # Return no. of mS RTC leads DS3231
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self.await_transition()
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rtc_time = now()
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rtc_ms = rtc_time[0] * 1000 + rtc_time[1]
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t_ds3231 = utime.mktime(self.get_time()) # To second precision, still in same sec as transition
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return rtc_ms - 1000 * t_ds3231
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def await_transition(self):
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def await_transition(self): # Wait until DS3231 seconds value changes
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data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)
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ss = data[0]
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while ss == data[0]:
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data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0) # Await a seconds transition
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data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)
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return data
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# Get calibration factor for Pyboard RTC. Note that the DS3231 doesn't have millisecond resolution so we
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# wait for a seconds transition to emulate it.
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# This function returns the required calibration factor for the RTC (approximately the no. of ppm the
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# RTC lags the DS3231).
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# For accurate results the delay should be at least 120 seconds. Longer is better.
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# For accurate results the delay should be at least two minutes. Longer is better.
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# Note calibration factor is not saved on power down unless an RTC backup battery is used. An option is
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# to store the calibration factor on disk and issue rtc.calibration(factor) on boot.
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def getcal(self, seconds):
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def getcal(self, minutes=5):
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rtc.calibration(0) # Clear existing cal
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self.save_time() # Set DS3231 from RTC
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self.await_transition()
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rtcstart = now()
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dsstart = utime.mktime(self.get_time())
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pyb.delay(seconds * 1000)
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pyb.delay(minutes * 60000)
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self.await_transition()
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rtcend = now()
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dsend = utime.mktime(self.get_time())
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dsdelta = (dsend - dsstart) *1000
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rtcdelta = rtcend[0] * 1000 + rtcend[1] - rtcstart[0] * 1000 - rtcstart[1]
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ppm = (1000000* (rtcdelta - dsdelta))/dsdelta
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return -ppm/0.954
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return int(-ppm/0.954)
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def calibrate(self, seconds):
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rtc.calibration(self.getcal(seconds))
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def calibrate(self, minutes=5):
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print('Waiting {} minutes to acquire calibration factor...'.format(minutes))
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cal = self.getcal(minutes)
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rtc.calibration(cal)
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print('Pyboard RTC is calibrated. Factor is {}.'.format(cal))
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return cal
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