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@sorz
Last active Sep 5, 2019
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Read and wite datetime on DS1307 via I2C by Python.
#!/usr/bin/env python
#encoding: utf-8
# Copyright (C) 2013 @XiErCh
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
from datetime import datetime
import smbus
def _bcd_to_int(bcd):
"""Decode a 2x4bit BCD to a integer.
"""
out = 0
for d in (bcd >> 4, bcd):
for p in (1, 2, 4 ,8):
if d & 1:
out += p
d >>= 1
out *= 10
return out / 10
def _int_to_bcd(n):
"""Encode a one or two digits number to the BCD.
"""
bcd = 0
for i in (n // 10, n % 10):
for p in (8, 4, 2, 1):
if i >= p:
bcd += 1
i -= p
bcd <<= 1
return bcd >> 1
class DS1307():
_REG_SECONDS = 0x00
_REG_MINUTES = 0x01
_REG_HOURS = 0x02
_REG_DAY = 0x03
_REG_DATE = 0x04
_REG_MONTH = 0x05
_REG_YEAR = 0x06
_REG_CONTROL = 0x07
def __init__(self, twi=1, addr=0x68):
self._bus = smbus.SMBus(twi)
self._addr = addr
def _write(self, register, data):
self._bus.write_byte_data(self._addr, register, data)
def _read(self, data):
return self._bus.read_byte_data(self._addr, data)
def _read_seconds(self):
return _bcd_to_int(self._read(self._REG_SECONDS))
def _read_minutes(self):
return _bcd_to_int(self._read(self._REG_MINUTES))
def _read_hours(self):
d = self._read(self._REG_HOURS)
if d & 0x40:
return _bcd_to_int(d & 0x3F)
else:
h = _bcd_to_int(d & 0x1F)
if d & 0x20:
h += 11 # Convert 12h to 24h
elif h == 12:
h = 0
return h
def _read_day(self):
return _bcd_to_int(self._read(self._REG_DAY))
def _read_date(self):
return _bcd_to_int(self._read(self._REG_DATE))
def _read_month(self):
return _bcd_to_int(self._read(self._REG_MONTH))
def _read_year(self):
return _bcd_to_int(self._read(self._REG_YEAR))
def read_all(self):
"""Return a tuple such as (year, month, date, day, hours, minutes,
seconds).
"""
return (self._read_year(), self._read_month(), self._read_date(),
self._read_day(), self._read_hours(), self._read_minutes(),
self._read_seconds())
def read_str(self):
"""Return a string such as 'YY-DD-MMTHH-MM-SS'.
"""
return '%02d-%02d-%02dT%02d:%02d:%02d' % (self._read_year(),
self._read_month(), self._read_date(), self._read_hours(),
self._read_minutes(), self._read_seconds())
def read_datetime(self, century=21, tzinfo=None):
"""Return the datetime.datetime object.
"""
return datetime((century - 1) * 100 + self._read_year(),
self._read_month(), self._read_date(), self._read_hours(),
self._read_minutes(), self._read_seconds(), 0, tzinfo=tzinfo)
def write_all(self, seconds=None, minutes=None, hours=None, day=None,
date=None, month=None, year=None, save_as_24h=True):
"""Direct write un-none value.
Range: seconds [0,59], minutes [0,59], hours [0,23],
day [0,7], date [1-31], month [1-12], year [0-99].
"""
if seconds is not None:
if seconds < 0 or seconds > 59:
raise ValueError('Seconds is out of range [0,59].')
self._write(self._REG_SECONDS, _int_to_bcd(seconds))
if minutes is not None:
if minutes < 0 or minutes > 59:
raise ValueError('Minutes is out of range [0,59].')
self._write(self._REG_MINUTES, _int_to_bcd(minutes))
if hours is not None:
if hours < 0 or hours > 23:
raise ValueError('Hours is out of range [0,23].')
if save_as_24h:
self._write(self._REG_HOURS, _int_to_bcd(hours) | 0x40)
else:
if hours == 0:
h = _int_to_bcd(12) | 0x32
elif hours <= 12:
h = _int_to_bcd(hours)
else:
h = _int_to_bcd(hours - 12) | 0x32
self._write(self._REG_HOURS, h)
if year is not None:
if year < 0 or year > 99:
raise ValueError('Years is out of range [0,99].')
self._write(self._REG_YEAR, _int_to_bcd(year))
if month is not None:
if month < 1 or month > 12:
raise ValueError('Month is out of range [1,12].')
self._write(self._REG_MONTH, _int_to_bcd(month))
if date is not None:
if date < 1 or date > 31:
raise ValueError('Date is out of range [1,31].')
self._write(self._REG_DATE, _int_to_bcd(date))
if day is not None:
if day < 1 or day > 7:
raise ValueError('Day is out of range [1,7].')
self._write(self._REG_DAY, _int_to_bcd(day))
def write_datetime(self, dt):
"""Write from a datetime.datetime object.
"""
self.write_all(dt.second, dt.minute, dt.hour,
dt.isoweekday(), dt.day, dt.month, dt.year % 100)
def write_now(self):
"""Equal to DS1307.write_datetime(datetime.datetime.now()).
"""
self.write_datetime(datetime.now())
def main():
ds = DS1307(1, 0x68)
print(ds.read_datetime())
#ds.write_now()
if __name__ == '__main__':
main()
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