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ds3231.py
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ds3231.py
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#! /usr/bin/env micropython
# Micropython driver for the DS3231 RTC Module
# Inspiration from work done by Mike Causer (mcauser) for the DS1307
# https://github.com/mcauser/micropython-tinyrtc-i2c/blob/master/ds1307.py
# The MIT License (MIT)
#
# Copyright (c) 2020 Willem Peterse
#
# 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 micropython import const
DATETIME_REG = const(0) # 7 bytes
ALARM1_REG = const(7) # 5 bytes
ALARM2_REG = const(11) # 4 bytes
CONTROL_REG = const(14)
STATUS_REG = const(15)
AGING_REG = const(16)
TEMPERATURE_REG = const(17) # 2 bytes
def dectobcd(decimal):
"""Convert decimal to binary coded decimal (BCD) format"""
return (decimal // 10) << 4 | (decimal % 10)
def bcdtodec(bcd):
"""Convert binary coded decimal to decimal"""
return ((bcd >> 4) * 10) + (bcd & 0x0F)
class DS3231:
""" DS3231 RTC driver.
Hard coded to work with year 2000-2099."""
FREQ_1 = const(1)
FREQ_1024 = const(2)
FREQ_4096 = const(3)
FREQ_8192 = const(4)
SQW_32K = const(1)
AL1_EVERY_S = const(15) # Alarm every second
AL1_MATCH_S = const(14) # Alarm when seconds match (every minute)
AL1_MATCH_MS = const(12) # Alarm when minutes, seconds match (every hour)
AL1_MATCH_HMS = const(8) # Alarm when hours, minutes, seconds match (every day)
AL1_MATCH_DHMS = const(0) # Alarm when day|wday, hour, min, sec match (specific wday / mday) (once per month/week)
AL2_EVERY_M = const(7) # Alarm every minute on 00 seconds
AL2_MATCH_M = const(6) # Alarm when minutes match (every hour)
AL2_MATCH_HM = const(4) # Alarm when hours and minutes match (every day)
AL2_MATCH_DHM = const(0) # Alarm when day|wday match (once per month/week)
def __init__(self, i2c, addr=0x68):
self.i2c = i2c
self.addr = addr
self._timebuf = bytearray(7) # Pre-allocate a buffer for the time data
self._buf = bytearray(1) # Pre-allocate a single bytearray for re-use
self._al1_buf = bytearray(4)
self._al2buf = bytearray(3)
def datetime(self, datetime=None):
"""Get or set datetime
Always sets or returns in 24h format, converts to 24h if clock is set to 12h format
datetime : tuple, (0-year, 1-month, 2-day, 3-hour, 4-minutes[, 5-seconds[, 6-weekday]])"""
if datetime is None:
self.i2c.readfrom_mem_into(self.addr, DATETIME_REG, self._timebuf)
# 0x00 - Seconds BCD
# 0x01 - Minutes BCD
# 0x02 - Hour 0 12/24 AM/PM/20s BCD
# 0x03 - WDay 1-7 0000 0 BCD
# 0x04 - Day 1-31 00 BCD
# 0x05 - Month 1-12 Century 00 BCD
# 0x06 - Year 0-99 BCD (2000-2099)
seconds = bcdtodec(self._timebuf[0])
minutes = bcdtodec(self._timebuf[1])
if (self._timebuf[2] & 0x40) >> 6: # Check for 12 hour mode bit
hour = bcdtodec(self._timebuf[2] & 0x9f) # Mask out bit 6(12/24) and 5(AM/PM)
if (self._timebuf[2] & 0x20) >> 5: # bit 5(AM/PM)
# PM
hour += 12
else:
# 24h mode
hour = bcdtodec(self._timebuf[2] & 0xbf) # Mask bit 6 (12/24 format)
weekday = bcdtodec(self._timebuf[3]) # Can be set arbitrarily by user (1,7)
day = bcdtodec(self._timebuf[4])
month = bcdtodec(self._timebuf[5] & 0x7f) # Mask out the century bit
year = bcdtodec(self._timebuf[6]) + 2000
if self.OSF():
print("WARNING: Oscillator stop flag set. Time may not be accurate.")
return (year, month, day, weekday, hour, minutes, seconds, 0) # Conforms to the ESP8266 RTC (v1.13)
# Set the clock
try:
self._timebuf[3] = dectobcd(datetime[6]) # Day of week
except IndexError:
self._timebuf[3] = 0
try:
self._timebuf[0] = dectobcd(datetime[5]) # Seconds
except IndexError:
self._timebuf[0] = 0
self._timebuf[1] = dectobcd(datetime[4]) # Minutes
self._timebuf[2] = dectobcd(datetime[3]) # Hour + the 24h format flag
self._timebuf[4] = dectobcd(datetime[2]) # Day
self._timebuf[5] = dectobcd(datetime[1]) & 0xff # Month + mask the century flag
self._timebuf[6] = dectobcd(int(str(datetime[0])[-2:])) # Year can be yyyy, or yy
self.i2c.writeto_mem(self.addr, DATETIME_REG, self._timebuf)
self._OSF_reset()
return True
def square_wave(self, freq=None):
"""Outputs Square Wave Signal
The alarm interrupts are disabled when enabling a square wave output. Disabling SWQ out does
not enable the alarm interrupts. Set them manually with the alarm_int() method.
freq : int,
Not given: returns current setting
False = disable SQW output,
1 = 1 Hz,
2 = 1.024 kHz,
3 = 4.096 kHz,
4 = 8.192 kHz"""
if freq is None:
return self.i2c.readfrom_mem(self.addr, CONTROL_REG, 1)[0]
if not freq:
# Set INTCN (bit 2) to 1 and both ALIE (bits 1 & 0) to 0
self.i2c.readfrom_mem_into(self.addr, CONTROL_REG, self._buf)
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([(self._buf[0] & 0xf8) | 0x04]))
else:
# Set the frequency in the control reg and at the same time set the INTCN to 0
freq -= 1
self.i2c.readfrom_mem_into(self.addr, CONTROL_REG, self._buf)
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([(self._buf[0] & 0xe3) | (freq << 3)]))
return True
def alarm1(self, time=None, match=AL1_MATCH_DHMS, int_en=True, weekday=False):
"""Set alarm1, can match mday, wday, hour, minute, second
time : tuple, (second,[ minute[, hour[, day]]])
weekday : bool, select mday (False) or wday (True)
match : int, match const
int_en : bool, enable interrupt on alarm match on SQW/INT pin (disables SQW output)"""
if time is None:
# TODO Return readable string
self.i2c.readfrom_mem_into(self.addr, ALARM1_REG, self._al1_buf)
return self._al1_buf
if isinstance(time, int):
time = (time,)
a1m4 = (match & 0x08) << 4
a1m3 = (match & 0x04) << 5
a1m2 = (match & 0x02) << 6
a1m1 = (match & 0x01) << 7
dydt = (1 << 6) if weekday else 0 # day / date bit
self._al1_buf[0] = dectobcd(time[0]) | a1m1 # second
self._al1_buf[1] = (dectobcd(time[1]) | a1m2) if len(time) > 1 else a1m2 # minute
self._al1_buf[2] = (dectobcd(time[2]) | a1m3) if len(time) > 2 else a1m3 # hour
self._al1_buf[3] = (dectobcd(time[3]) | a1m4 | dydt) if len(time) > 3 else a1m4 | dydt # day (wday|mday)
self.i2c.writeto_mem(self.addr, ALARM1_REG, self._al1_buf)
# Set the interrupt bit
self.alarm_int(enable=int_en, alarm=1)
# Check the alarm (will reset the alarm flag)
self.check_alarm(1)
return self._al1_buf
def alarm2(self, time=None, match=AL2_MATCH_DHM, int_en=True, weekday=False):
"""Get/set alarm 2 (can match minute, hour, day)
time : tuple, (minute[, hour[, day]])
weekday : bool, select mday (False) or wday (True)
match : int, match const
int_en : bool, enable interrupt on alarm match on SQW/INT pin (disables SQW output)
Returns : bytearray(3), the alarm settings register"""
if time is None:
# TODO Return readable string
self.i2c.readfrom_mem_into(self.addr, ALARM2_REG, self._al2buf)
return self._al2buf
if isinstance(time, int):
time = (time,)
a2m4 = (match & 0x04) << 5 # masks
a2m3 = (match & 0x02) << 6
a2m2 = (match & 0x01) << 7
dydt = (1 << 6) if weekday else 0 # day / date bit
self._al2buf[0] = dectobcd(time[0]) | a2m2 if len(time) > 1 else a2m2 # minute
self._al2buf[1] = dectobcd(time[1]) | a2m3 if len(time) > 2 else a2m3 # hour
self._al2buf[2] = dectobcd(time[2]) | a2m4 | dydt if len(time) > 3 else a2m4 | dydt # day
self.i2c.writeto_mem(self.addr, ALARM2_REG, self._al2buf)
# Set the interrupt bits
self.alarm_int(enable=int_en, alarm=2)
# Check the alarm (will reset the alarm flag)
self.check_alarm(2)
return self._al2buf
def alarm_int(self, enable=True, alarm=0):
"""Enable/disable interrupt for alarm1, alarm2 or both.
Enabling the interrupts disables the SQW output
enable : bool, enable/disable interrupts
alarm : int, alarm nr (0 to set both interrupts)
returns: the control register"""
if alarm in (0, 1):
self.i2c.readfrom_mem_into(self.addr, CONTROL_REG, self._buf)
if enable:
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([(self._buf[0] & 0xfa) | 0x05]))
else:
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([self._buf[0] & 0xfe]))
if alarm in (0, 2):
self.i2c.readfrom_mem_into(self.addr, CONTROL_REG, self._buf)
if enable:
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([(self._buf[0] & 0xf9) | 0x06]))
else:
self.i2c.writeto_mem(self.addr, CONTROL_REG, bytearray([self._buf[0] & 0xfd]))
return self.i2c.readfrom_mem(self.addr, CONTROL_REG, 1)
def check_alarm(self, alarm):
"""Check if the alarm flag is set and clear the alarm flag"""
self.i2c.readfrom_mem_into(self.addr, STATUS_REG, self._buf)
if (self._buf[0] & alarm) == 0:
# Alarm flag not set
return False
# Clear alarm flag bit
self.i2c.writeto_mem(self.addr, STATUS_REG, bytearray([self._buf[0] & ~alarm]))
return True
def output_32kHz(self, enable=True):
"""Enable or disable the 32.768 kHz square wave output"""
status = self.i2c.readfrom_mem(self.addr, STATUS_REG, 1)[0]
if enable:
self.i2c.writeto_mem(self.addr, STATUS_REG, bytearray([status | (1 << 3)]))
else:
self.i2c.writeto_mem(self.addr, STATUS_REG, bytearray([status & (~(1 << 3))]))
def OSF(self):
"""Returns the oscillator stop flag (OSF).
1 indicates that the oscillator is stopped or was stopped for some
period in the past and may be used to judge the validity of
the time data.
returns : bool"""
return bool(self.i2c.readfrom_mem(self.addr, STATUS_REG, 1)[0] >> 7)
def _OSF_reset(self):
"""Clear the oscillator stop flag (OSF)"""
self.i2c.readfrom_mem_into(self.addr, STATUS_REG, self._buf)
self.i2c.writeto_mem(self.addr, STATUS_REG, bytearray([self._buf[0] & 0x7f]))
def _is_busy(self):
"""Returns True when device is busy doing TCXO management"""
return bool(self.i2c.readfrom_mem(self.addr, STATUS_REG, 1)[0] & (1 << 2))