Description

Class definition header for the MCP7940 from Microchip. Both the MCP7940N (with battery backup pin and the MCP7940M are supported with this library and they both use the same I2C address. This chip is a Real-Time-Clock with an I2C interface. The data sheet located at http://ww1.microchip.com/downloads/en/DeviceDoc/20002292B.pdf describes the functionality used in this library.
se is made of portions of Adafruit's RTClib Version 1.2.0 at https://github.com/adafruit/RTClib which is a fork of the original RTClib from Jeelabs. The re-used code encompasses only the classes for time and date.

configuration

This library is built with the standard "Doxyfile", which is located at https://github.com/Zanduino/Common/blob/main/Doxygen. As described on that page, there are only 5 environment variables used, and these are set in the project's actions file, located at https://github.com/Zanduino/MCP7940/blob/master/.github/workflows/ci-doxygen.yml Edit this file and set the 5 variables: PRETTYNAME, PROJECT_NAME, PROJECT_NUMBER, PROJECT_BRIEF and PROJECT_LOGO so that these values are used in the doxygen documentation. The local copy of the doxyfile should be in the project's root directory in order to do local doxygen testing, but the file is ignored on upload to GitHub.

clang-format

Part of the GitHub actions for CI is running every source file through "clang-format" to ensure that coding formatting is done the same for all files. The configuration file ".clang-format" is located at https://github.com/Zanduino/Common/tree/main/clang-format and this is used for CI tests when pushing to GitHub. The local file, if present in the root directory, is ignored when committing and uploading.

GNU General Public License v3.0

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Author

Written by Arnd Arnd@.nosp@m.Zand.nosp@m.uino..nosp@m.Com at https://www.github.com/SV-Zanshin

Changelog

Version	Date	Developer	Comments
1.2.2	2023-06-12	Mark-Wills	Issue #65 - Corrected return value
1.2.2	2021-12-16	BrotherV	Issue #63 - Add ESP8266 support for defining SDA and SCL pins.
1.2.1	2021-05-23	SV-Zanshin	Issue #60 - Correct handling of dates < 2000-01-01
1.2.1	2021-01-06	SV-Zanshin	Issue #58 - Corrected return reference values in readRAM and readEUI and added writeEUI
1.2.1	2021-01-05	masterx1981	Issue #58 - Add support for MCP79401 and MCP79402 read EUI data
1.1.9	2020-11-26	SV-Zanshin	Issue #54 - Optimize c++ code / resilience. Uniform Initialization. Consolidated I2C calls.
1.1.8	2020-11-15	SV-Zanshin	Issue #50 - Reformat with "clang-format"
1.1.8	2020-11-14	SV-Zanshin	Issue #49 - corrections for Battery Backup mode
1.1.7	2020-05-18	wvmarle	Issue #47 - adjust() method with compiler variables fix
1.1.7	2019-02-07	davidlehrian	Issue #43 - Calib. may cause overflow of "trim" variable
1.1.7	2019-02-07	davidlehrian	Issue #42 - calibrate(DateTime) to correct current dt/tm
1.1.6	2019-01-27	davidlehrian	Issue #36 - Reopened, changed statements to avoid warn.
1.1.5	2019-01-19	SV-Zanshin	Issue #40 - Change structure and layout to use doxygen
1.1.5	2019-01-19	INemesisI	Issue #37 - AlarmPolarity bit clearing on setAlarm()
1.1.5	2019-01-19	SV-Zanshin	Issue #39 - Changes to avoid Travis-CI warnings
1.1.5	2019-01-18	INemesisI	Issue #38 - Overflow on setting new TRIM value
1.1.4	2018-12-15	hexeguitar	Issue #36 - Overflow on I2C_MODES datatype corrected
1.1.4	2018-12-15	huynh213	Issue #35 - MCP7940.adjust() resets the PWRFAIL/VBATEN
1.1.3	2018-08-08	amgrays	Issue #32 - invalid return on SetMFP corrected
1.1.3	2018-08-05	HannesJo0139	Issue #31 - Calibration trim on negative numbers
1.1.2	2018-08-04	SV-Zanshin	Issue #28 - added calibrate() ovld for freq. calibration
1.1.2	2018-07-08	logicaprogrammabile	Issue #26 - regarding hour bitmasks
1.1.1	2018-07-07	SV-Zanshin	Fixed bugs introduced by 14, 20, and 21
1.1.1	2018-07-07	wvmarle	Pull #21 - Additional changes
1.1.1	2018-07-06	wvmarle	Pull #20 - Numerous changes and enhancements
1.1.0	2018-07-05	wvmarle	Pull #14 - bug fixes to alarm state and comment cleanup
1.0.8	2018-07-02	SV-Zanshin	Added guard code for multiple I2C constant definitions
1.0.8	2018-06-30	SV-Zanshin	Issue #15 - Added I2C Speed selection
1.0.7	2018-06-21	SV-Zanshin	Issue #13 - DateTime.dayOfTheWeek() is 0-6 instead 1-7
1.0.6	2018-04-29	SV-Zanshin	Issue #7 - Moved param defaults to prototypes
1.0.6	2018-04-29	SV-Zanshin	Issue #10 - Setting of alarm with WKDAY to future date
1.0.5b	2017-12-18	SV-Zanshin	Issue #8 - Setting to 24-Hour clock
1.0.5a	2017-10-31	SV-Zanshin	Issue #6 - Remove classification on template functions
1.0.4c	2017-08-13	SV-Zanshin	Issue #5 - Remove checks after Wire.requestFrom()
1.0.4b	2017-08-08	SV-Zanshin	Replaced readRAM and writeRAM with template functions
1.0.4a	2017-08-06	SV-Zanshin	Removed unnecessary MCP7940_I2C_Delay and all references
1.0.3	2017-08-05	SV-Zanshin	Added calls for MCP7940N. getPowerFail(),clearPowerFail(), setBattery(). Added I2C_READ_ATTEMPTS to prevent I2C hang, added getPowerUp/Down()
1.0.3a	2017-07-29	SV-Zanshin	Cleaned up comments, no code changes
1.0.3	2017-07-29	SV-Zanshin	getSQWSpeed(),setSQWSpeed(),setSQWState(),getSQWState()
1.0.2	2017-07-29	SV-Zanshin	getAlarm(),setAlarmState(),getAlarmState(),isAlarm()added optional setting setAlarm(). Fixed alarm 1 index
1.0.1	2017-07-25	SV-Zanshin	Overloaded Calibrate() to manually set trim factor
1.0.0	2017-07-23	SV-Zanshin	Cleaned up code, initial github upload
1.0.2b	2017-07-20	SV-Zanshin	Added alarm handling
1.0.1b	2017-07-19	SV-Zanshin	Added methods
1.0.0b	2017-07-17	SV-Zanshin	Initial coding