Implement setting date-time

Implement setting time
Fix partial writing to only write to a range instead of until the end
2020-05-16 17:25:00 +02:00 · 2020-05-16 17:19:54 +02:00 · 2020-05-16 17:19:25 +02:00 · 2020-05-16 17:03:30 +02:00 · 2020-05-16 17:02:54 +02:00 · 2020-05-16 17:01:19 +02:00
21 changed files with 906 additions and 1610 deletions
--- a/.clang-format
+++ b/.clang-format
@@ -0,0 +1,13 @@
+---
+BasedOnStyle: LLVM
+ColumnLimit: 120
+IndentWidth: 4
+TabWidth: 4
+UseTab: ForIndentation
+AlignEscapedNewlines: DontAlign
+AllowShortFunctionsOnASingleLine: Empty
+AlwaysBreakTemplateDeclarations: true
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterFunction: true
+...
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,10 @@
 Release
 Debug
 *.componentinfo.xml
-avrdude.bat
+*.elf
+*.o
+*.hex
+*.srec
+*.eeprom
+*.lss
+*.map
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +0,0 @@
-[submodule "ds3231/usart"]
-	path = ds3231/usart
-	url = git@blackmark.me:usart.git
--- a/21
+++ b/21
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 BlackMark
+
+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 (including the next
+paragraph) 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.
--- a/ds3231.atsln
+++ b/ds3231.atsln
@@ -1,22 +0,0 @@
-
-Microsoft Visual Studio Solution File, Format Version 12.00
-# Atmel Studio Solution File, Format Version 11.00
-VisualStudioVersion = 14.0.25420.1
-MinimumVisualStudioVersion = 10.0.40219.1
-Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "ds3231", "ds3231\ds3231.cppproj", "{DCE6C7E3-EE26-4D79-826B-08594B9AD897}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|AVR = Debug|AVR
-		Release|AVR = Release|AVR
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.ActiveCfg = Debug|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.Build.0 = Debug|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.ActiveCfg = Release|AVR
-		{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.Build.0 = Release|AVR
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-EndGlobal
--- a/ds3231.hpp
+++ b/ds3231.hpp
@@ -0,0 +1,214 @@
+#pragma once
+
+#include "../clock.hpp"
+
+#include <stddef.h>
+
+#include "../i2c/i2c.hpp"
+#include "../type/type.hpp"
+
+#include "registers.hpp"
+
+namespace rtc {
+
+struct Date {
+	uint16_t year;
+	uint8_t month;
+	uint8_t day;
+};
+
+struct Time {
+	uint8_t hour;
+	uint8_t minute;
+	uint8_t second;
+};
+
+struct DateTime : Date, Time {
+};
+
+template <typename I2cDriver, bool SetDayOfWeek = true>
+class DS3231 {
+  public:
+	static constexpr auto I2C_ADDRESS = 0x68;
+
+	static constexpr auto TIME_REG_ADDR = 0x00;
+	static constexpr auto ALARM1_REG_ADDR = 0x07;
+	static constexpr auto ALARM2_REG_ADDR = 0x0B;
+	static constexpr auto CONTROL_REG_ADDR = 0x0E;
+	static constexpr auto CONTROL_STATUS_REG_ADDR = 0x0F;
+	static constexpr auto AGING_OFFSET_REG_ADDR = 0x10;
+	static constexpr auto TEMP_REG_ADDR = 0x11;
+
+	// Construction does not call init and is only available for convenience
+	DS3231() = default;
+
+	// Moving and copying ds3231 objects is not supported
+	DS3231(const DS3231 &) = delete;
+	DS3231(DS3231 &&) = delete;
+	DS3231 &operator=(const DS3231 &) = delete;
+	DS3231 &operator=(DS3231 &&) = delete;
+
+	static inline void init()
+	{
+		I2cDriver::init();
+	}
+
+	static auto getDate()
+	{
+		const auto timeReg = readRegister<TIME_REG_ADDR>();
+
+		Date date;
+		date.year = timeReg.getYear();
+		date.month = timeReg.getMonth();
+		date.day = timeReg.getDate();
+		return date;
+	}
+	static auto getTime()
+	{
+		const auto timeReg = readRegister<TIME_REG_ADDR>();
+
+		Time time;
+		time.hour = timeReg.getHours();
+		time.minute = timeReg.getMinutes();
+		time.second = timeReg.getSeconds();
+		return time;
+	}
+	static auto getDateTime()
+	{
+		const auto timeReg = readRegister<TIME_REG_ADDR>();
+
+		DateTime dateTime;
+		dateTime.year = timeReg.getYear();
+		dateTime.month = timeReg.getMonth();
+		dateTime.day = timeReg.getDate();
+		dateTime.hour = timeReg.getHours();
+		dateTime.minute = timeReg.getMinutes();
+		dateTime.second = timeReg.getSeconds();
+		return dateTime;
+	}
+
+	static void setDate(const Date &date)
+	{
+		detail::TimeReg timeReg;
+		timeReg.setYear(date.year);
+		timeReg.setMonth(date.month);
+		timeReg.setDate(date.day);
+		if constexpr (SetDayOfWeek)
+			timeReg.setDay(calcDayOfWeek(date.year, date.month, date.day) + 1);
+
+		constexpr auto DATE_START_OFFSET = offsetof(detail::TimeReg, day);
+		constexpr auto DATE_END_OFFSET = offsetof(detail::TimeReg, year);
+
+		writePartialRegister<TIME_REG_ADDR, DATE_START_OFFSET, DATE_END_OFFSET>(timeReg);
+	}
+	static void setTime(const Time &time)
+	{
+		detail::TimeReg timeReg;
+		timeReg.setHours(time.hour);
+		timeReg.setMinutes(time.minute);
+		timeReg.setSeconds(time.second);
+
+		constexpr auto TIME_START_OFFSET = offsetof(detail::TimeReg, seconds);
+		constexpr auto TIME_END_OFFSET = offsetof(detail::TimeReg, hours);
+
+		writePartialRegister<TIME_REG_ADDR, TIME_START_OFFSET, TIME_END_OFFSET>(timeReg);
+	}
+	static void setDateTime(const DateTime &dateTime)
+	{
+		detail::TimeReg timeReg;
+		timeReg.setYear(dateTime.year);
+		timeReg.setMonth(dateTime.month);
+		timeReg.setDate(dateTime.day);
+		if constexpr (SetDayOfWeek)
+			timeReg.setDay(calcDayOfWeek(dateTime.year, dateTime.month, dateTime.day) + 1);
+
+		timeReg.setHours(dateTime.hour);
+		timeReg.setMinutes(dateTime.minute);
+		timeReg.setSeconds(dateTime.second);
+
+		constexpr auto START_OFFSET = offsetof(detail::TimeReg, seconds);
+		constexpr auto END_OFFSET = offsetof(detail::TimeReg, year);
+
+		writePartialRegister<TIME_REG_ADDR, START_OFFSET, END_OFFSET>(timeReg);
+	}
+
+  private:
+	template <uint8_t Address, typename Register>
+	static Register readRegisterHelper()
+	{
+		I2cDriver::template start<I2C_ADDRESS>(false);
+		I2cDriver::write(Address);
+		I2cDriver::stop();
+
+		Register reg;
+		I2cDriver::template start<I2C_ADDRESS>(true);
+		I2cDriver::template readBytes<sizeof(Register)>(reinterpret_cast<uint8_t *>(&reg));
+		I2cDriver::stop();
+		return reg;
+	}
+
+	template <uint8_t Address>
+	static auto readRegister()
+	{
+		if constexpr (Address == TIME_REG_ADDR) {
+			return readRegisterHelper<Address, detail::TimeReg>();
+		} else if constexpr (Address == ALARM1_REG_ADDR) {
+			return readRegisterHelper<Address, detail::Alarm1Reg>();
+		} else if constexpr (Address == ALARM2_REG_ADDR) {
+			return readRegisterHelper<Address, detail::Alarm2Reg>();
+		} else if constexpr (Address == CONTROL_REG_ADDR) {
+			return readRegisterHelper<Address, detail::ControlReg>();
+		} else if constexpr (Address == CONTROL_STATUS_REG_ADDR) {
+			return readRegisterHelper<Address, detail::ControlStatusReg>();
+		} else if constexpr (Address == AGING_OFFSET_REG_ADDR) {
+			return readRegisterHelper<Address, detail::AgingOffsetReg>();
+		} else if constexpr (Address == TEMP_REG_ADDR) {
+			return readRegisterHelper<Address, detail::TempReg>();
+		} else {
+			static_assert(type::always_false_v<decltype(Address)>, "Invalid register address");
+		}
+	}
+
+	template <uint8_t Address, uint8_t StartOffset, uint8_t EndOffset, typename Register>
+	static void writePartialRegister(const Register &reg)
+	{
+		static_assert(StartOffset <= EndOffset, "Invalid offset range");
+		static_assert(StartOffset < sizeof(Register), "Start offset out of bounds");
+		static_assert(EndOffset < sizeof(Register), "End offset out of bounds");
+
+		constexpr auto WRITE_SIZE = EndOffset + 1 - StartOffset;
+		static_assert(StartOffset + WRITE_SIZE <= sizeof(Register), "Writing out of bounds");
+
+		if constexpr (Address == TIME_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::TimeReg>, "Invalid register type");
+		} else if constexpr (Address == ALARM1_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::Alarm1Reg>, "Invalid register type");
+		} else if constexpr (Address == ALARM2_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::Alarm2Reg>, "Invalid register type");
+		} else if constexpr (Address == CONTROL_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::ControlReg>, "Invalid register type");
+		} else if constexpr (Address == CONTROL_STATUS_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::ControlStatusReg>, "Invalid register type");
+		} else if constexpr (Address == AGING_OFFSET_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::AgingOffsetReg>, "Invalid register type");
+		} else if constexpr (Address == TEMP_REG_ADDR) {
+			static_assert(type::is_same_v<Register, detail::TempReg>, "Invalid register type");
+		} else {
+			static_assert(type::always_false_v<Register>, "Invalid register address");
+		}
+
+		I2cDriver::template start<I2C_ADDRESS>(false);
+		I2cDriver::write(Address + StartOffset);
+		I2cDriver::template writeBytes<WRITE_SIZE>(reinterpret_cast<const uint8_t *>(&reg) + StartOffset);
+		I2cDriver::stop();
+	}
+
+	static uint8_t calcDayOfWeek(uint16_t year, uint8_t month, uint16_t day)
+	{
+		day += month < 3 ? year-- : year - 2;
+		const auto dayOfWeek = (23 * month / 9 + day + 4 + year / 4 - year / 100 + year / 400);
+		return dayOfWeek % 7;
+	}
+};
+
+} // namespace rtc
--- a/ds3231/bootloader.h
+++ b/ds3231/bootloader.h
@@ -1,56 +0,0 @@
-/*
-* Copyright (c) by BlackMark 2016
-* Date 09/09/2016
-* Version 1.4
-*/
-
-#ifndef BOOTLOADER_H
-#define BOOTLOADER_H
-
-#include <avr/pgmspace.h>
-#include <avr/interrupt.h>
-#include <avr/wdt.h>
-
-typedef void (*flash)() __attribute__ ((noreturn));
-
-flash boot = reinterpret_cast<flash>( 0x0000 );
-flash bootloader = reinterpret_cast<flash>( 0x7E00 / 2 );
-
-inline bool checkBootloader()
-{
-	if( pgm_read_byte( reinterpret_cast<uint16_t>( bootloader ) * 2 ) == 0xF8 )
-	{
-		return true;
-	}
-
-	return false;
-}
-
-inline void callBootloader()
-{
-	if( checkBootloader() )
-	{
-		bootloader();
-	}
-	else
-	{
-		boot();
-	}
-}
-
-inline uint8_t handleReset()
-{
-	wdt_reset();
-	uint8_t ui8MCUSR = MCUSR;
-	MCUSR &= ~( 1 << WDRF );
-	wdt_disable();
-	return ui8MCUSR;
-}
-
-inline void reset()
-{
-	wdt_enable( WDTO_15MS );
-	while( true );
-}
-
-#endif
--- a/ds3231/clock.h
+++ b/ds3231/clock.h
@@ -1,14 +0,0 @@
-/*
-* Copyright (c) by BlackMark 2015
-* Date 24/11/2015
-* Version 1.1
-*/
-
-#ifndef CLOCK_H
-#define CLOCK_H
-
-#define F_CPU 8000000
-
-#include <util/delay.h>
-
-#endif
--- a/ds3231/ds3231.cppproj
+++ b/ds3231/ds3231.cppproj
@@ -1,247 +0,0 @@
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-        <avrgcccpp.compiler.optimization.level>Optimize (-O1)</avrgcccpp.compiler.optimization.level>
-        <avrgcccpp.compiler.optimization.PackStructureMembers>True</avrgcccpp.compiler.optimization.PackStructureMembers>
-        <avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>True</avrgcccpp.compiler.optimization.AllocateBytesNeededForEnum>
-        <avrgcccpp.compiler.optimization.DebugLevel>Default (-g2)</avrgcccpp.compiler.optimization.DebugLevel>
-        <avrgcccpp.compiler.warnings.AllWarnings>True</avrgcccpp.compiler.warnings.AllWarnings>
-        <avrgcccpp.compiler.warnings.Pedantic>True</avrgcccpp.compiler.warnings.Pedantic>
-        <avrgcccpp.compiler.miscellaneous.OtherFlags>-Wextra -std=c++14</avrgcccpp.compiler.miscellaneous.OtherFlags>
-        <avrgcccpp.linker.libraries.Libraries>
-          <ListValues>
-            <Value>libm</Value>
-          </ListValues>
-        </avrgcccpp.linker.libraries.Libraries>
-        <avrgcccpp.assembler.general.IncludePaths>
-          <ListValues>
-            <Value>%24(PackRepoDir)\Atmel\ATmega_DFP\1.2.193\include</Value>
-          </ListValues>
-        </avrgcccpp.assembler.general.IncludePaths>
-        <avrgcccpp.assembler.debugging.DebugLevel>Default (-Wa,-g)</avrgcccpp.assembler.debugging.DebugLevel>
-      </AvrGccCpp>
-    </ToolchainSettings>
-    <PreBuildEvent>echo "C:\bin\avrdude-6.3\avrdude.exe" -v -p$(avrdevice) %%* -Uflash:w:"$(OutputDirectory)\$(Name).hex":i &gt; "$(MSBuildProjectDirectory)\avrdude.bat"</PreBuildEvent>
-  </PropertyGroup>
-  <ItemGroup>
-    <Compile Include="bootloader.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="clock.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="main.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="rtc.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="rtc.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="systime.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="systime.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="twi-lowlevel.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="twi-lowlevel.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="twi.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="twi.h">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="usart\usart.cpp">
-      <SubType>compile</SubType>
-    </Compile>
-    <Compile Include="usart\usart.h">
-      <SubType>compile</SubType>
-    </Compile>
-  </ItemGroup>
-  <ItemGroup>
-    <Folder Include="usart" />
-  </ItemGroup>
-  <Import Project="$(AVRSTUDIO_EXE_PATH)\\Vs\\Compiler.targets" />
-</Project>
--- a/ds3231/main.cpp
+++ b/ds3231/main.cpp
@@ -1,178 +0,0 @@
-/*
-* Copyright (c) by BlackMark 2017
-* Date 17/12/2017
-* Version 1.2
-*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <time.h>
-#include <avr/interrupt.h>
-
-#include "usart/usart.h"
-#include "clock.h"
-#include "bootloader.h"
-#include "systime.h"
-
-void setup()
-{
-	USART0 &cSerial = USART0::inst();
-
-	if( SysTime::init() )
-	{
-		cSerial << "DS3231 detected!" << "\r\n";
-	}
-	else
-	{
-		cSerial << "ERROR - No RTC detected!" << "\r\n";
-	}
-}
-
-void setTime()
-{
-	USART0 &cSerial = USART0::inst();
-
-	tm sTime;
-
-	constexpr auto BUFFER_SIZE = 32;
-	char szBuffer[BUFFER_SIZE];
-
-	cSerial << "Set time:" << "\r\n" << "Year: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_year = atoi( szBuffer ) - 1900;
-
-	cSerial << "Set time:" << "\r\n" << "Month: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_mon = atoi( szBuffer ) - 1;
-
-	cSerial << "Set time:" << "\r\n" << "Day: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_mday = atoi( szBuffer );
-
-	cSerial << "Set time:" << "\r\n" << "Hour: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_hour = atoi( szBuffer );
-
-	cSerial << "Minute: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_min = atoi( szBuffer );
-
-	cSerial << "Second: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	sTime.tm_sec = atoi( szBuffer );
-
-	mktime( &sTime );
-
-	SysTime::setTime( sTime );
-}
-
-void setAlarm()
-{
-	USART0 &cSerial = USART0::inst();
-
-	rtc_tm* tmAlarm = rtc_get_alarm();
-
-	constexpr auto BUFFER_SIZE = 32;
-	char szBuffer[BUFFER_SIZE];
-
-	cSerial << "Set alarm:" << "\r\n" << "Hour: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	tmAlarm->hour = atoi( szBuffer );
-
-	cSerial << "Minute: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	tmAlarm->min = atoi( szBuffer );
-
-	cSerial << "Second: ";
-	cSerial.receiveLine( szBuffer, BUFFER_SIZE, "\r" );
-	cSerial << szBuffer << "\r\n";
-	tmAlarm->sec = atoi( szBuffer );
-
-	rtc_set_alarm( tmAlarm );
-}
-
-int main()
-{
-	uint8_t ui8MCUSR = handleReset();
-
-	if( ui8MCUSR & ( 1 << WDRF ) )
-	{
-		callBootloader();
-	}
-
-	USART0 &cSerial = USART0::inst();
-
-	cSerial.init( 9600 );
-	sei();
-
-	setup();
-
-	constexpr auto BUFFER_SIZE = 32;
-	char szBuffer[BUFFER_SIZE];
-
-	while( true )
-	{
-		if( !SysTime::checkSync() )
-		{
-			SysTime::syncSysTime();
-
-			time_t timeNow = time( nullptr );
-			tm *psLocalTime = localtime( &timeNow );
-
-			strftime( szBuffer, BUFFER_SIZE, "%F %T %z", psLocalTime );
-
-			cSerial << "Time: " << szBuffer << "\r\n";
-
-			if( rtc_check_alarm() )
-			{
-				cSerial << "ALARM!" << "\r\n";
-			}
-		}
-
-		uint8_t ui8Cmd;
-
-		if( cSerial.receiveByte( ui8Cmd ) )
-		{
-			if( ui8Cmd == 'b' )
-			{
-				cSerial << "Bootloader . . . " << "\r\n";
-				_delay_ms( 1000 );
-				reset();
-			}
-			else if( ui8Cmd == 's' )
-			{
-				setTime();
-			}
-			else if( ui8Cmd == 'a' )
-			{
-				setAlarm();
-			}
-			else if( ui8Cmd == 'p' )
-			{
-				uint8_t ui8Hour;
-				uint8_t ui8Minute;
-				uint8_t ui8Second;
-
-				rtc_get_alarm_s( &ui8Hour, &ui8Minute, &ui8Second );
-				sprintf( szBuffer, "Alarm set to: %02d:%02d:%02d", ui8Hour, ui8Minute, ui8Second );
-				cSerial << szBuffer << "\r\n";
-			}
-			else
-			{
-				cSerial << "Invalid char: '";
-				cSerial.transmitByte( ui8Cmd );
-				cSerial << "'" << "\r\n";
-			}
-		}
-	}
-
-	return 0;
-}
--- a/ds3231/systime.cpp
+++ b/ds3231/systime.cpp
@@ -1,107 +0,0 @@
-#include "systime.h"
-
-//////////////////////////////////////////////////////////////////////////
-// DST magic by Edgar Bonet
-int SysTime::euDST( const time_t *pTime, int32_t *pZ )
-{
-	static_cast<void>( pZ );
-
-	uint32_t t = *pTime;
-
-	if( static_cast<uint8_t>( t >> 24 ) >= 194 )
-		t -= 3029443200U;
-
-	t = ( t + 655513200 ) / 604800 * 28;
-
-	if( static_cast<uint16_t>( t % 1461 ) < 856 )
-		return ONE_HOUR;
-
-	return 0;
-}
-
-//////////////////////////////////////////////////////////////////////////
-bool SysTime::init()
-{
-	twi_init_master();
-	rtc_init();
-
-	if( !rtc_is_ds3231() )
-		return false;
-
-	set_zone( 1 * ONE_HOUR );
-	set_dst( euDST );
-
-	syncSysTime();
-
-	return true;
-}
-
-//////////////////////////////////////////////////////////////////////////
-void SysTime::syncSysTime()
-{
-	tm sTime = getTime();
-	set_system_time( mk_gmtime( &sTime ) );
-}
-
-//////////////////////////////////////////////////////////////////////////
-bool SysTime::checkSync()
-{
-	time_t timeNow = time( nullptr );
-	tm *ptmUTC = gmtime( &timeNow );
-
-	rtc_tm *ptmRtcTime = rtc_get_time();
-
-	if( ptmUTC->tm_sec != ptmRtcTime->sec || ptmUTC->tm_min != ptmRtcTime->min || ptmUTC->tm_hour != ptmRtcTime->hour )
-		return false;
-
-	if( ptmUTC->tm_mday != ptmRtcTime->mday || ( ptmUTC->tm_mon + 1 ) != ptmRtcTime->mon || ( ptmUTC->tm_year + 1900 ) != ptmRtcTime->year )
-		return false;
-
-	return true;
-}
-
-//////////////////////////////////////////////////////////////////////////
-void SysTime::tick()
-{
-	system_tick();
-}
-
-//////////////////////////////////////////////////////////////////////////
-tm SysTime::getTime()
-{
-	tm sTime;
-	rtc_tm *ptmTime = rtc_get_time();
-
-	sTime.tm_sec = ptmTime->sec;
-	sTime.tm_min = ptmTime->min;
-	sTime.tm_hour = ptmTime->hour;
-	sTime.tm_mday = ptmTime->mday;
-	sTime.tm_mon = ptmTime->mon - 1;
-	sTime.tm_year = ptmTime->year - 1900;
-	sTime.tm_isdst = 0;
-
-	time_t timeUTC = mk_gmtime( &sTime );
-	sTime = *( gmtime( &timeUTC ) );
-
-	return sTime;
-}
-
-//////////////////////////////////////////////////////////////////////////
-void SysTime::setTime( const tm &sTime )
-{
-	rtc_tm *pRtcTime = rtc_get_time();
-	
-	pRtcTime->sec = sTime.tm_sec;
-	pRtcTime->min = sTime.tm_min;
-	pRtcTime->hour = sTime.tm_hour;
-	pRtcTime->mday = sTime.tm_mday;
-	pRtcTime->mon = sTime.tm_mon + 1;
-	pRtcTime->year = sTime.tm_year + 1900;
-	pRtcTime->wday = sTime.tm_wday + 1;
-	pRtcTime->am = ( sTime.tm_hour < 12 ) ? true : false;
-	pRtcTime->twelveHour = ( sTime.tm_hour == 0 ) ? 12 : ( ( sTime.tm_hour > 12 ) ? ( sTime.tm_hour - 12 ) : sTime.tm_hour );
-
-	rtc_set_time( pRtcTime );
-
-	syncSysTime();
-}
--- a/ds3231/systime.h
+++ b/ds3231/systime.h
@@ -1,29 +0,0 @@
-/*
-* Copyright (c) by BlackMark 2017
-* Date 17/12/2016
-* Version 1.0
-*/
-
-#ifndef SYSTIME_H
-#define SYSTIME_H
-
-#include <time.h>
-
-#include "twi.h"
-#include "rtc.h"
-
-class SysTime
-{
-private:
-	static int euDST( const time_t *pTime, int32_t *pZ );
-
-public:
-	static bool init();
-	static void syncSysTime();
-	static bool checkSync();
-	static void tick();
-	static tm getTime();
-	static void setTime( const tm &sTime );
-};
-
-#endif
--- a/ds3231/twi-lowlevel.cpp
+++ b/ds3231/twi-lowlevel.cpp
@@ -1,476 +0,0 @@
-/*
-  twi.c - TWI/I2C library for Wiring & Arduino
-  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
-
-  This library is free software; you can redistribute it and/or
-  modify it under the terms of the GNU Lesser General Public
-  License as published by the Free Software Foundation; either
-  version 2.1 of the License, or (at your option) any later version.
-
-  This library 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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public
-  License along with this library; if not, write to the Free Software
-  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-
-#include <math.h>
-#include <stdlib.h>
-#include <inttypes.h>
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <compat/twi.h>
-
-#ifndef cbi
-#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
-#endif
-
-#ifndef sbi
-#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
-#endif
-
-#include "twi-lowlevel.h"
-
-static volatile uint8_t twi_state;
-static uint8_t twi_slarw;
-
-static void (*twi_onSlaveTransmit)(void);
-static void (*twi_onSlaveReceive)(uint8_t*, int);
-
-static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
-static volatile uint8_t twi_masterBufferIndex;
-static uint8_t twi_masterBufferLength;
-
-static uint8_t twi_txBuffer[TWI_BUFFER_LENGTH];
-static volatile uint8_t twi_txBufferIndex;
-static volatile uint8_t twi_txBufferLength;
-
-static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
-static volatile uint8_t twi_rxBufferIndex;
-
-static volatile uint8_t twi_error;
-
-/* 
- * Function twi_init
- * Desc     readys twi pins and sets twi bitrate
- * Input    none
- * Output   none
- */
-void twi_init(void)
-{
-  // initialize state
-  twi_state = TWI_READY;
-
-  #if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__)
-    // activate internal pull-ups for twi
-    // as per note from atmega8 manual pg167
-    sbi(PORTC, 4);
-    sbi(PORTC, 5);
-  #else
-    // activate internal pull-ups for twi
-    // as per note from atmega128 manual pg204
-    sbi(PORTD, 0);
-    sbi(PORTD, 1);
-  #endif
-
-  // initialize twi prescaler and bit rate
-  cbi(TWSR, TWPS0);
-  cbi(TWSR, TWPS1);
-  TWBR = ((CPU_FREQ / TWI_FREQ) - 16) / 2;
-
-  /* twi bit rate formula from atmega128 manual pg 204
-  SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
-  note: TWBR should be 10 or higher for master mode
-  It is 72 for a 16mhz Wiring board with 100kHz TWI */
-
-  // enable twi module, acks, and twi interrupt
-  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
-}
-
-/* 
- * Function twi_slaveInit
- * Desc     sets slave address and enables interrupt
- * Input    none
- * Output   none
- */
-void twi_setAddress(uint8_t address)
-{
-  // set twi slave address (skip over TWGCE bit)
-  TWAR = address << 1;
-}
-
-/* 
- * Function twi_readFrom
- * Desc     attempts to become twi bus master and read a
- *          series of bytes from a device on the bus
- * Input    address: 7bit i2c device address
- *          data: pointer to byte array
- *          length: number of bytes to read into array
- * Output   number of bytes read
- */
-uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length)
-{
-  uint8_t i;
-
-  // ensure data will fit into buffer
-  if(TWI_BUFFER_LENGTH < length){
-    return 0;
-  }
-
-  // wait until twi is ready, become master receiver
-  while(TWI_READY != twi_state){
-    continue;
-  }
-  twi_state = TWI_MRX;
-  // reset error state (0xFF.. no error occured)
-  twi_error = 0xFF;
-
-  // initialize buffer iteration vars
-  twi_masterBufferIndex = 0;
-  twi_masterBufferLength = length-1;  // This is not intuitive, read on...
-  // On receive, the previously configured ACK/NACK setting is transmitted in
-  // response to the received byte before the interrupt is signalled. 
-  // Therefor we must actually set NACK when the _next_ to last byte is
-  // received, causing that NACK to be sent in response to receiving the last
-  // expected byte of data.
-
-  // build sla+w, slave device address + w bit
-  twi_slarw = TW_READ;
-  twi_slarw |= address << 1;
-
-  // send start condition
-  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
-
-  // wait for read operation to complete
-  while(TWI_MRX == twi_state){
-    continue;
-  }
-
-  if (twi_masterBufferIndex < length)
-    length = twi_masterBufferIndex;
-
-  // copy twi buffer to data
-  for(i = 0; i < length; ++i){
-    data[i] = twi_masterBuffer[i];
-  }
-	
-  return length;
-}
-
-/* 
- * Function twi_writeTo
- * Desc     attempts to become twi bus master and write a
- *          series of bytes to a device on the bus
- * Input    address: 7bit i2c device address
- *          data: pointer to byte array
- *          length: number of bytes in array
- *          wait: boolean indicating to wait for write or not
- * Output   0 .. success
- *          1 .. length to long for buffer
- *          2 .. address send, NACK received
- *          3 .. data send, NACK received
- *          4 .. other twi error (lost bus arbitration, bus error, ..)
- */
-uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait)
-{
-  uint8_t i;
-
-  // ensure data will fit into buffer
-  if(TWI_BUFFER_LENGTH < length){
-    return 1;
-  }
-
-  // wait until twi is ready, become master transmitter
-  while(TWI_READY != twi_state){
-    continue;
-  }
-  twi_state = TWI_MTX;
-  // reset error state (0xFF.. no error occured)
-  twi_error = 0xFF;
-
-  // initialize buffer iteration vars
-  twi_masterBufferIndex = 0;
-  twi_masterBufferLength = length;
-  
-  // copy data to twi buffer
-  for(i = 0; i < length; ++i){
-    twi_masterBuffer[i] = data[i];
-  }
-  
-  // build sla+w, slave device address + w bit
-  twi_slarw = TW_WRITE;
-  twi_slarw |= address << 1;
-  
-  // send start condition
-  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
-
-  // wait for write operation to complete
-  while(wait && (TWI_MTX == twi_state)){
-    continue;
-  }
-  
-  if (twi_error == 0xFF)
-    return 0;	// success
-  else if (twi_error == TW_MT_SLA_NACK)
-    return 2;	// error: address send, nack received
-  else if (twi_error == TW_MT_DATA_NACK)
-    return 3;	// error: data send, nack received
-  else
-    return 4;	// other twi error
-}
-
-/* 
- * Function twi_transmit
- * Desc     fills slave tx buffer with data
- *          must be called in slave tx event callback
- * Input    data: pointer to byte array
- *          length: number of bytes in array
- * Output   1 length too long for buffer
- *          2 not slave transmitter
- *          0 ok
- */
-uint8_t twi_transmit(uint8_t* data, uint8_t length)
-{
-  uint8_t i;
-
-  // ensure data will fit into buffer
-  if(TWI_BUFFER_LENGTH < length){
-    return 1;
-  }
-  
-  // ensure we are currently a slave transmitter
-  if(TWI_STX != twi_state){
-    return 2;
-  }
-  
-  // set length and copy data into tx buffer
-  twi_txBufferLength = length;
-  for(i = 0; i < length; ++i){
-    twi_txBuffer[i] = data[i];
-  }
-  
-  return 0;
-}
-
-/* 
- * Function twi_attachSlaveRxEvent
- * Desc     sets function called before a slave read operation
- * Input    function: callback function to use
- * Output   none
- */
-void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
-{
-  twi_onSlaveReceive = function;
-}
-
-/* 
- * Function twi_attachSlaveTxEvent
- * Desc     sets function called before a slave write operation
- * Input    function: callback function to use
- * Output   none
- */
-void twi_attachSlaveTxEvent( void (*function)(void) )
-{
-  twi_onSlaveTransmit = function;
-}
-
-/* 
- * Function twi_reply
- * Desc     sends byte or readys receive line
- * Input    ack: byte indicating to ack or to nack
- * Output   none
- */
-void twi_reply(uint8_t ack)
-{
-  // transmit master read ready signal, with or without ack
-  if(ack){
-    TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
-  }else{
-	  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
-  }
-}
-
-/* 
- * Function twi_stop
- * Desc     relinquishes bus master status
- * Input    none
- * Output   none
- */
-void twi_stop(void)
-{
-  // send stop condition
-  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
-
-  // wait for stop condition to be exectued on bus
-  // TWINT is not set after a stop condition!
-  while(TWCR & _BV(TWSTO)){
-    continue;
-  }
-
-  // update twi state
-  twi_state = TWI_READY;
-}
-
-/* 
- * Function twi_releaseBus
- * Desc     releases bus control
- * Input    none
- * Output   none
- */
-void twi_releaseBus(void)
-{
-  // release bus
-  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
-
-  // update twi state
-  twi_state = TWI_READY;
-}
-
-SIGNAL(TWI_vect)
-{
-  switch(TW_STATUS){
-    // All Master
-    case TW_START:     // sent start condition
-    case TW_REP_START: // sent repeated start condition
-      // copy device address and r/w bit to output register and ack
-      TWDR = twi_slarw;
-      twi_reply(1);
-      break;
-
-    // Master Transmitter
-    case TW_MT_SLA_ACK:  // slave receiver acked address
-    case TW_MT_DATA_ACK: // slave receiver acked data
-      // if there is data to send, send it, otherwise stop 
-      if(twi_masterBufferIndex < twi_masterBufferLength){
-        // copy data to output register and ack
-        TWDR = twi_masterBuffer[twi_masterBufferIndex++];
-        twi_reply(1);
-      }else{
-        twi_stop();
-      }
-      break;
-    case TW_MT_SLA_NACK:  // address sent, nack received
-      twi_error = TW_MT_SLA_NACK;
-      twi_stop();
-      break;
-    case TW_MT_DATA_NACK: // data sent, nack received
-      twi_error = TW_MT_DATA_NACK;
-      twi_stop();
-      break;
-    case TW_MT_ARB_LOST: // lost bus arbitration
-      twi_error = TW_MT_ARB_LOST;
-      twi_releaseBus();
-      break;
-
-    // Master Receiver
-    case TW_MR_DATA_ACK: // data received, ack sent
-      // put byte into buffer
-      twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
-    case TW_MR_SLA_ACK:  // address sent, ack received
-      // ack if more bytes are expected, otherwise nack
-      if(twi_masterBufferIndex < twi_masterBufferLength){
-        twi_reply(1);
-      }else{
-        twi_reply(0);
-      }
-      break;
-    case TW_MR_DATA_NACK: // data received, nack sent
-      // put final byte into buffer
-      twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
-    case TW_MR_SLA_NACK: // address sent, nack received
-      twi_stop();
-      break;
-    // TW_MR_ARB_LOST handled by TW_MT_ARB_LOST case
-
-    // Slave Receiver
-    case TW_SR_SLA_ACK:   // addressed, returned ack
-    case TW_SR_GCALL_ACK: // addressed generally, returned ack
-    case TW_SR_ARB_LOST_SLA_ACK:   // lost arbitration, returned ack
-    case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
-      // enter slave receiver mode
-      twi_state = TWI_SRX;
-      // indicate that rx buffer can be overwritten and ack
-      twi_rxBufferIndex = 0;
-      twi_reply(1);
-      break;
-    case TW_SR_DATA_ACK:       // data received, returned ack
-    case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
-      // if there is still room in the rx buffer
-      if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
-        // put byte in buffer and ack
-        twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
-        twi_reply(1);
-      }else{
-        // otherwise nack
-        twi_reply(0);
-      }
-      break;
-    case TW_SR_STOP: // stop or repeated start condition received
-      // put a null char after data if there's room
-      if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
-        twi_rxBuffer[twi_rxBufferIndex] = '\0';
-      }
-      // sends ack and stops interface for clock stretching
-      twi_stop();
-      // callback to user defined callback
-      twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
-      // since we submit rx buffer to "wire" library, we can reset it
-      twi_rxBufferIndex = 0;
-      // ack future responses and leave slave receiver state
-      twi_releaseBus();
-      break;
-    case TW_SR_DATA_NACK:       // data received, returned nack
-    case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
-      // nack back at master
-      twi_reply(0);
-      break;
-    
-    // Slave Transmitter
-    case TW_ST_SLA_ACK:          // addressed, returned ack
-    case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
-      // enter slave transmitter mode
-      twi_state = TWI_STX;
-      // ready the tx buffer index for iteration
-      twi_txBufferIndex = 0;
-      // set tx buffer length to be zero, to verify if user changes it
-      twi_txBufferLength = 0;
-      // request for txBuffer to be filled and length to be set
-      // note: user must call twi_transmit(bytes, length) to do this
-      twi_onSlaveTransmit();
-      // if they didn't change buffer & length, initialize it
-      if(0 == twi_txBufferLength){
-        twi_txBufferLength = 1;
-        twi_txBuffer[0] = 0x00;
-      }
-      // transmit first byte from buffer, fall
-    case TW_ST_DATA_ACK: // byte sent, ack returned
-      // copy data to output register
-      TWDR = twi_txBuffer[twi_txBufferIndex++];
-      // if there is more to send, ack, otherwise nack
-      if(twi_txBufferIndex < twi_txBufferLength){
-        twi_reply(1);
-      }else{
-        twi_reply(0);
-      }
-      break;
-    case TW_ST_DATA_NACK: // received nack, we are done 
-    case TW_ST_LAST_DATA: // received ack, but we are done already!
-      // ack future responses
-      twi_reply(1);
-      // leave slave receiver state
-      twi_state = TWI_READY;
-      break;
-
-    // All
-    case TW_NO_INFO:   // no state information
-      break;
-    case TW_BUS_ERROR: // bus error, illegal stop/start
-      twi_error = TW_BUS_ERROR;
-      twi_stop();
-      break;
-  }
-}
-
--- a/ds3231/twi-lowlevel.h
+++ b/ds3231/twi-lowlevel.h
@@ -1,57 +0,0 @@
-/*
-  twi.h - TWI/I2C library for Wiring & Arduino
-  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
-
-  This library is free software; you can redistribute it and/or
-  modify it under the terms of the GNU Lesser General Public
-  License as published by the Free Software Foundation; either
-  version 2.1 of the License, or (at your option) any later version.
-
-  This library 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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public
-  License along with this library; if not, write to the Free Software
-  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-
-#ifndef twi_h
-#define twi_h
-
-#include <inttypes.h>
-
-//#define ATMEGA8
-
-#ifndef CPU_FREQ
-#define CPU_FREQ 16000000L
-#endif
-
-#ifndef TWI_FREQ
-#define TWI_FREQ 100000L
-#endif
-
-#ifndef TWI_BUFFER_LENGTH
-#define TWI_BUFFER_LENGTH 32
-#endif
-
-#define TWI_READY 0
-#define TWI_MRX   1
-#define TWI_MTX   2
-#define TWI_SRX   3
-#define TWI_STX   4
-
-void twi_init(void);
-void twi_setAddress(uint8_t);
-uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t);
-uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t);
-uint8_t twi_transmit(uint8_t*, uint8_t);
-void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) );
-void twi_attachSlaveTxEvent( void (*)(void) );
-void twi_reply(uint8_t);
-void twi_stop(void);
-void twi_releaseBus(void);
-
-#endif
-
--- a/ds3231/twi.cpp
+++ b/ds3231/twi.cpp
@@ -1,226 +0,0 @@
-/*
-  TwoWire.cpp - TWI/I2C library for Wiring & Arduino
-  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
-
-  This library is free software; you can redistribute it and/or
-  modify it under the terms of the GNU Lesser General Public
-  License as published by the Free Software Foundation; either
-  version 2.1 of the License, or (at your option) any later version.
-
-  This library 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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public
-  License along with this library; if not, write to the Free Software
-  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-
-#include <stdlib.h>
-#include <string.h>
-#include <inttypes.h>
-#include "twi-lowlevel.h"
-
-#include "twi.h"
-
-// local variables
-uint8_t rxBuffer[BUFFER_LENGTH];
-uint8_t rxBufferIndex = 0;
-uint8_t rxBufferLength = 0;
-
-uint8_t txAddress = 0;
-uint8_t txBuffer[BUFFER_LENGTH];
-uint8_t txBufferIndex = 0;
-uint8_t txBufferLength = 0;
-
-uint8_t transmitting = 0;
-void (*user_onRequest)(void);
-void (*user_onReceive)(int);
-
-void onRequestService(void);
-void onReceiveService(uint8_t*, int);
-
-void twi_init_master(void)
-{
-  rxBufferIndex = 0;
-  rxBufferLength = 0;
-
-  txBufferIndex = 0;
-  txBufferLength = 0;
-
-  twi_init();
-}
-
-void twi_init_slave(uint8_t address)
-{
-  twi_setAddress(address);
-  twi_attachSlaveTxEvent(onRequestService);
-  twi_attachSlaveRxEvent(onReceiveService);
-  twi_init_master();
-}
-
-uint8_t twi_request_from(uint8_t address, uint8_t quantity)
-{
-  // clamp to buffer length
-  if(quantity > BUFFER_LENGTH){
-    quantity = BUFFER_LENGTH;
-  }
-  // perform blocking read into buffer
-  uint8_t read = twi_readFrom(address, rxBuffer, quantity);
-  // set rx buffer iterator vars
-  rxBufferIndex = 0;
-  rxBufferLength = read;
-
-  return read;
-}
-
-void twi_begin_transmission(uint8_t address)
-{
-  // indicate that we are transmitting
-  transmitting = 1;
-  // set address of targeted slave
-  txAddress = address;
-  // reset tx buffer iterator vars
-  txBufferIndex = 0;
-  txBufferLength = 0;
-}
-
-uint8_t twi_end_transmission(void)
-{
-  // transmit buffer (blocking)
-  int8_t ret = twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
-  // reset tx buffer iterator vars
-  txBufferIndex = 0;
-  txBufferLength = 0;
-  // indicate that we are done transmitting
-  transmitting = 0;
-  return ret;
-}
-
-// must be called in:
-// slave tx event callback
-// or after beginTransmission(address)
-void twi_send_byte(uint8_t data)
-{
-  if(transmitting){
-  // in master transmitter mode
-    // don't bother if buffer is full
-    if(txBufferLength >= BUFFER_LENGTH){
-      return;
-    }
-    // put byte in tx buffer
-    txBuffer[txBufferIndex] = data;
-    ++txBufferIndex;
-    // update amount in buffer   
-    txBufferLength = txBufferIndex;
-  }else{
-  // in slave send mode
-    // reply to master
-    twi_transmit(&data, 1);
-  }
-}
-
-// must be called in:
-// slave tx event callback
-// or after beginTransmission(address)
-void twi_send(uint8_t* data, uint8_t quantity)
-{
-  if(transmitting){
-  // in master transmitter mode
-    for(uint8_t i = 0; i < quantity; ++i){
-     twi_send_byte(data[i]);
-    }
-  }else{
-  // in slave send mode
-    // reply to master
-    twi_transmit(data, quantity);
-  }
-}
-
-// must be called in:
-// slave tx event callback
-// or after beginTransmission(address)
-void twi_send_char(char* data)
-{
-  twi_send((uint8_t*)data, strlen(data));
-}
-
-// must be called in:
-// slave rx event callback
-// or after requestFrom(address, numBytes)
-uint8_t twi_available(void)
-{
-  return rxBufferLength - rxBufferIndex;
-}
-
-// must be called in:
-// slave rx event callback
-// or after requestFrom(address, numBytes)
-uint8_t twi_receive(void)
-{
-  // default to returning null char
-  // for people using with char strings
-  uint8_t value = '\0';
-  
-  // get each successive byte on each call
-  if(rxBufferIndex < rxBufferLength){
-    value = rxBuffer[rxBufferIndex];
-    ++rxBufferIndex;
-  }
-
-  return value;
-}
-
-// behind the scenes function that is called when data is received
-void onReceiveService(uint8_t* inBytes, int numBytes)
-{
-  // don't bother if user hasn't registered a callback
-  if(!user_onReceive){
-    return;
-  }
-  // don't bother if rx buffer is in use by a master requestFrom() op
-  // i know this drops data, but it allows for slight stupidity
-  // meaning, they may not have read all the master requestFrom() data yet
-  if(rxBufferIndex < rxBufferLength){
-    return;
-  }
-  // copy twi rx buffer into local read buffer
-  // this enables new reads to happen in parallel
-  for(uint8_t i = 0; i < numBytes; ++i){
-    rxBuffer[i] = inBytes[i];    
-  }
-  // set rx iterator vars
-  rxBufferIndex = 0;
-  rxBufferLength = numBytes;
-  // alert user program
-  user_onReceive(numBytes);
-}
-
-// behind the scenes function that is called when data is requested
-void onRequestService(void)
-{
-  // don't bother if user hasn't registered a callback
-  if(!user_onRequest){
-    return;
-  }
-  // reset tx buffer iterator vars
-  // !!! this will kill any pending pre-master sendTo() activity
-  txBufferIndex = 0;
-  txBufferLength = 0;
-  // alert user program
-  user_onRequest();
-}
-
-// sets function called on slave write
-void twi_set_on_receive( void (*function)(int) )
-{
-  user_onReceive = function;
-}
-
-// sets function called on slave read
-void twi_set_on_request( void (*function)(void) )
-{
-  user_onRequest = function;
-}
-
--- a/ds3231/twi.h
+++ b/ds3231/twi.h
@@ -1,40 +0,0 @@
-/*
-  TwoWire.h - TWI/I2C library for Arduino & Wiring
-  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
-
-  This library is free software; you can redistribute it and/or
-  modify it under the terms of the GNU Lesser General Public
-  License as published by the Free Software Foundation; either
-  version 2.1 of the License, or (at your option) any later version.
-
-  This library 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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public
-  License along with this library; if not, write to the Free Software
-  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-
-#ifndef TwoWire_h
-#define TwoWire_h
-
-#include <inttypes.h>
-
-#define BUFFER_LENGTH 32
-
-void twi_init_master(void);
-void twi_init_slave(uint8_t);
-void twi_begin_transmission(uint8_t);
-uint8_t twi_end_transmission(void);
-uint8_t twi_request_from(uint8_t, uint8_t);
-void twi_send_byte(uint8_t);
-void twi_send(uint8_t*, uint8_t);
-void twi_send_char(char*);
-uint8_t twi_available(void);
-uint8_t twi_receive(void);
-void twi_set_on_receive( void (*)(int) );
-void twi_set_on_request( void (*)(void) );
-
-#endif
--- a/ds3231/usart
+++ b/ds3231/usart
--- a/flags.hpp
+++ b/flags.hpp
@@ -0,0 +1,71 @@
+#pragma once
+
+namespace rtc {
+
+namespace detail {
+
+template <typename FlagsT>
+struct [[gnu::packed]] FlagsImpl
+{
+	static_assert(sizeof(FlagsT) == sizeof(uint8_t), "Must use uint8_t enum class flags");
+
+	uint8_t data = 0;
+	using Flags = FlagsT;
+
+	FlagsImpl() : data(0) {}
+	FlagsImpl(const Flags &flag) : data(static_cast<uint8_t>(flag)) {}
+
+	FlagsImpl(const FlagsImpl &other) : data(other.data) {}
+	FlagsImpl(const FlagsImpl &&) = delete;
+
+	FlagsImpl &operator=(const FlagsImpl &rhs)
+	{
+		data = rhs.data;
+		return *this;
+	}
+	FlagsImpl &operator=(const FlagsImpl &&) = delete;
+
+	FlagsImpl &operator=(const FlagsT &rhs)
+	{
+		data = static_cast<uint8_t>(rhs);
+		return *this;
+	}
+
+	FlagsImpl &operator|=(const FlagsT &flag)
+	{
+		data |= static_cast<uint8_t>(flag);
+		return *this;
+	}
+
+	FlagsImpl &operator&=(const FlagsT &flag)
+	{
+		data &= static_cast<uint8_t>(flag);
+		return *this;
+	}
+
+	FlagsImpl &operator~()
+	{
+		data = ~data;
+		return *this;
+	}
+};
+
+template <typename FlagsT>
+FlagsT operator|(const FlagsT &lhs, const FlagsT &rhs)
+{
+	const auto lhsInt = static_cast<uint8_t>(lhs);
+	const auto rhsInt = static_cast<uint8_t>(rhs);
+	return static_cast<FlagsT>(lhsInt | rhsInt);
+}
+
+template <typename FlagsT>
+FlagsT operator&(const FlagsT &lhs, const FlagsT &rhs)
+{
+	const auto lhsInt = static_cast<uint8_t>(lhs);
+	const auto rhsInt = static_cast<uint8_t>(rhs);
+	return static_cast<FlagsT>(lhsInt & rhsInt);
+}
+
+} // namespace detail
+
+} // namespace rtc
--- a/registers.hpp
+++ b/registers.hpp
@@ -0,0 +1,419 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "flags.hpp"
+
+namespace rtc {
+
+namespace detail {
+
+//////////////////////////////////////////////////////////////////////////
+
+template <uint8_t Mask = 0xFF>
+static inline uint8_t toBcd(const uint8_t &data)
+{
+	return ((data / 10 * 16) + (data % 10)) & Mask;
+}
+
+template <uint8_t Mask = 0xFF>
+static inline uint8_t fromBcd(const uint8_t &data)
+{
+	const auto maskedData = data & Mask;
+	return ((maskedData / 16 * 10) + (maskedData % 16));
+}
+
+static inline uint8_t convertTo24Hour(const uint8_t &hoursReg)
+{
+	constexpr auto FLAG_12_HOUR = 6;
+	constexpr auto FLAG_PM = 5;
+
+	const bool time12HourFormat = (hoursReg >> FLAG_12_HOUR) & 1;
+
+	if (time12HourFormat) {
+		const auto pmFlag = (hoursReg >> FLAG_PM) & 1;
+		constexpr auto HOUR_12_MASK = 0b00011111;
+		const auto hour12 = fromBcd<HOUR_12_MASK>(hoursReg);
+		if (hour12 == 12 && !pmFlag)
+			return 0;
+		return hour12 + pmFlag ? 12 : 0;
+	} else // 24 hour format
+	{
+		constexpr auto HOUR_MASK = 0b00111111;
+		return fromBcd<HOUR_MASK>(hoursReg);
+	}
+}
+
+template <uint8_t Mask = 0b01111111>
+static inline uint8_t getMaskedBcd(const uint8_t &reg)
+{
+	return fromBcd<Mask>(reg);
+}
+
+template <uint8_t Mask = 0b01111111>
+static inline void setMaskedBcd(uint8_t &reg, const uint8_t &value)
+{
+	reg &= ~Mask;
+	reg |= toBcd<Mask>(value);
+}
+
+static inline bool getEncodedDay(uint8_t &value, const uint8_t &reg)
+{
+	constexpr auto DAY_FLAG = 6;
+	if ((reg >> DAY_FLAG) & 1) {
+		constexpr auto DAY_MASK = 0b00001111;
+		value = reg & DAY_MASK;
+		return true;
+	}
+
+	return false;
+}
+
+static inline bool getEncodedDate(uint8_t &value, const uint8_t &reg)
+{
+	constexpr auto DAY_FLAG = 6;
+	if (!((reg >> DAY_FLAG) & 1)) {
+		value = getMaskedBcd<0b00111111>(reg);
+		return true;
+	}
+
+	return false;
+}
+
+static inline void setEncodedDay(uint8_t &reg, const uint8_t &value)
+{
+	constexpr auto DAY_MASK = 0b11110000;
+	reg &= DAY_MASK;
+	reg |= value & DAY_MASK;
+	constexpr auto DAY_FLAG = 6;
+	reg |= (1 << DAY_FLAG);
+}
+
+static inline void setEncodedDate(uint8_t &reg, const uint8_t &value)
+{
+	setMaskedBcd<0b00111111>(reg, value);
+	constexpr auto DAY_FLAG = 6;
+	reg &= ~(1 << DAY_FLAG);
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+struct [[gnu::packed]] TimeReg
+{
+	uint8_t seconds = 0;
+	uint8_t minutes = 0;
+	uint8_t hours = 0;
+	uint8_t day = 1; // Range 1-7 according to datasheet
+	uint8_t date = 0;
+	uint8_t month_century = 0;
+	uint8_t year = 0;
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline uint8_t getSeconds() const
+	{
+		return getMaskedBcd(seconds);
+	}
+	inline uint8_t getMinutes() const
+	{
+		return getMaskedBcd(minutes);
+	}
+	inline uint8_t getHours() const
+	{
+		return convertTo24Hour(hours);
+	}
+	inline uint8_t getDay() const
+	{
+		return getMaskedBcd<0b00000111>(day);
+	}
+	inline uint8_t getDate() const
+	{
+		return getMaskedBcd<0b00111111>(date);
+	}
+	inline uint8_t getMonth() const
+	{
+		return getMaskedBcd<0b00011111>(month_century);
+	}
+	inline bool getCentury() const
+	{
+		constexpr auto CENTURY_FLAG = 7;
+		return (month_century >> CENTURY_FLAG) & 1;
+	}
+	inline uint16_t getYear() const
+	{
+		return 2000 + fromBcd(year);
+	}
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline void setSeconds(uint8_t seconds)
+	{
+		setMaskedBcd(this->seconds, seconds);
+	}
+	inline void setMinutes(uint8_t minutes)
+	{
+		setMaskedBcd(this->minutes, minutes);
+	}
+	inline void setHours(uint8_t hours)
+	{
+		setMaskedBcd(this->hours, hours);
+	}
+	inline void setDay(uint8_t day)
+	{
+		this->day = day & 0b111;
+	}
+	inline void setDate(uint8_t date)
+	{
+		setMaskedBcd<0b00111111>(this->date, date);
+	}
+	inline void setMonth(uint8_t month)
+	{
+		setMaskedBcd<0b00011111>(month_century, month);
+	}
+	inline void setCentury(bool century)
+	{
+		constexpr auto CENTURY_POS = 7;
+		month_century &= ~(1 << CENTURY_POS);
+		month_century |= (century << CENTURY_POS);
+	}
+	inline void setYear(uint16_t year)
+	{
+		year = year % 100;
+		this->year = toBcd(year);
+	}
+};
+
+static_assert(sizeof(TimeReg) == 7, "Invalid time register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+struct [[gnu::packed]] Alarm1Reg
+{
+	uint8_t seconds = 0;
+	uint8_t minutes = 0;
+	uint8_t hours = 0;
+	uint8_t day_date = 0;
+
+	enum class AlarmRate {
+		ONCE_PER_S = 0b1111,
+		WHEN_S_MATCH = 0b1110,
+		WHEN_M_S_MATCH = 0b1100,
+		WHEN_H_M_S_MATCH = 0b1000,
+		WHEN_DATE_H_M_S_MATCH = 0b00000,
+		WHEN_DAY_H_N_S_MATCH = 0b10000,
+	};
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline uint8_t getSeconds() const
+	{
+		return getMaskedBcd(seconds);
+	}
+	inline uint8_t getMinutes() const
+	{
+		return getMaskedBcd(minutes);
+	}
+	inline uint8_t getHours() const
+	{
+		return convertTo24Hour(hours);
+	}
+	inline bool getDay(uint8_t & day) const
+	{
+		return getEncodedDay(day, day_date);
+	}
+	inline bool getDate(uint8_t & date) const
+	{
+		return getEncodedDate(date, day_date);
+	}
+	inline AlarmRate getAlarmRate() const
+	{
+		constexpr auto M_FLAG = 7;
+		const auto m1 = (seconds >> M_FLAG) & 1;
+		const auto m2 = (minutes >> M_FLAG) & 1;
+		const auto m3 = (hours >> M_FLAG) & 1;
+		const auto m4 = (day_date >> M_FLAG) & 1;
+		const auto m = (m4 << 3) | (m3 << 2) | (m2 << 1) | (m1 << 0);
+		if (m == 0) {
+			constexpr auto DAY_FLAG = 6;
+			const auto dayFormat = ((day_date >> DAY_FLAG) & 1) << 4;
+			return static_cast<AlarmRate>(dayFormat);
+		}
+		return static_cast<AlarmRate>(m);
+	}
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline void setSeconds(uint8_t seconds)
+	{
+		setMaskedBcd(this->seconds, seconds);
+	}
+	inline void setMinutes(uint8_t minutes)
+	{
+		setMaskedBcd(this->minutes, minutes);
+	}
+	inline void setHours(uint8_t hours)
+	{
+		setMaskedBcd(this->hours, hours);
+	}
+	inline void setDay(uint8_t day)
+	{
+		setEncodedDay(day_date, day);
+	}
+	inline void setDate(uint8_t date)
+	{
+		setEncodedDate(day_date, date);
+	}
+	inline void setAlarmRate(const AlarmRate &alarmRate)
+	{
+		const auto alarmRateFlags = static_cast<uint8_t>(alarmRate);
+		constexpr auto M_FLAG = 7;
+		seconds &= ~(1 << M_FLAG);
+		seconds |= (alarmRateFlags & 1) << M_FLAG;
+		minutes &= ~(1 << M_FLAG);
+		minutes |= ((alarmRateFlags >> 1) & 1) << M_FLAG;
+		hours &= ~(1 << M_FLAG);
+		hours |= ((alarmRateFlags >> 2) & 1) << M_FLAG;
+		day_date &= ~(1 << M_FLAG);
+		day_date |= ((alarmRateFlags >> 3) & 1) << M_FLAG;
+	}
+};
+
+static_assert(sizeof(Alarm1Reg) == 4, "Invalid alarm1 register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+struct [[gnu::packed]] Alarm2Reg
+{
+	uint8_t minutes = 0;
+	uint8_t hours = 0;
+	uint8_t day_date = 0;
+
+	enum class AlarmRate {
+		ONCE_PER_M = 0b111,
+		WHEN_M_MATCH = 0b110,
+		WHEN_H_M_MATCH = 0b100,
+		WHEN_DATE_H_M_MATCH = 0b0000,
+		WHEN_DAY_H_N_MATCH = 0b1000,
+	};
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline uint8_t getMinutes() const
+	{
+		return getMaskedBcd(minutes);
+	}
+	inline uint8_t getHours() const
+	{
+		return convertTo24Hour(hours);
+	}
+	inline bool getDay(uint8_t & day) const
+	{
+		return getEncodedDay(day, day_date);
+	}
+	inline bool getDate(uint8_t & date) const
+	{
+		return getEncodedDate(date, day_date);
+	}
+	inline AlarmRate getAlarmRate() const
+	{
+		constexpr auto M_FLAG = 7;
+		const auto m2 = (minutes >> M_FLAG) & 1;
+		const auto m3 = (hours >> M_FLAG) & 1;
+		const auto m4 = (day_date >> M_FLAG) & 1;
+		const auto m = (m4 << 2) | (m3 << 1) | (m2 << 0);
+		if (m == 0) {
+			constexpr auto DAY_FLAG = 6;
+			const auto dayFormat = ((day_date >> DAY_FLAG) & 1) << 3;
+			return static_cast<AlarmRate>(dayFormat);
+		}
+		return static_cast<AlarmRate>(m);
+	}
+
+	//////////////////////////////////////////////////////////////////////////
+
+	inline void setMinutes(uint8_t minutes)
+	{
+		setMaskedBcd(this->minutes, minutes);
+	}
+	inline void setHours(uint8_t hours)
+	{
+		setMaskedBcd(this->hours, hours);
+	}
+	inline void setDay(uint8_t day)
+	{
+		setEncodedDay(day_date, day);
+	}
+	inline void setDate(uint8_t date)
+	{
+		setEncodedDate(day_date, date);
+	}
+	inline void setAlarmRate(const AlarmRate &alarmRate)
+	{
+		const auto alarmRateFlags = static_cast<uint8_t>(alarmRate);
+		constexpr auto M_FLAG = 7;
+		minutes &= ~(1 << M_FLAG);
+		minutes |= (alarmRateFlags & 1) << M_FLAG;
+		hours &= ~(1 << M_FLAG);
+		hours |= ((alarmRateFlags >> 1) & 1) << M_FLAG;
+		day_date &= ~(1 << M_FLAG);
+		day_date |= ((alarmRateFlags >> 2) & 1) << M_FLAG;
+	}
+};
+
+static_assert(sizeof(Alarm2Reg) == 3, "Invalid alarm2 register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+enum class ControlRegFlags : uint8_t {
+	N_EOSC = 1 << 7,
+	BBSQW = 1 << 6,
+	CONV = 1 << 5,
+	RS2 = 1 << 4,
+	RS1 = 1 << 3,
+	INTCN = 1 << 2,
+	A2IE = 1 << 1,
+	A1IE = 1 << 0,
+};
+
+struct [[gnu::packed]] ControlReg : FlagsImpl<ControlRegFlags>{};
+
+static_assert(sizeof(ControlReg) == 1, "Invalid control register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+enum class ControlStatusRegFlags : uint8_t {
+	OSF = 1 << 7,
+	EN32KHZ = 1 << 3,
+	BSY = 1 << 2,
+	A2F = 1 << 1,
+	A1F = 1 << 0,
+};
+
+struct [[gnu::packed]] ControlStatusReg : FlagsImpl<ControlStatusRegFlags>{};
+
+static_assert(sizeof(ControlStatusReg) == 1, "Invalid control/status register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+struct [[gnu::packed]] AgingOffsetReg
+{
+	uint8_t data = 0;
+};
+
+static_assert(sizeof(AgingOffsetReg) == 1, "Invalid aging offset register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+struct [[gnu::packed]] TempReg
+{
+	uint8_t msb_temp = 0;
+	uint8_t lsb_temp = 0;
+};
+
+static_assert(sizeof(TempReg) == 2, "Invalid temperature register size");
+
+//////////////////////////////////////////////////////////////////////////
+
+} // namespace detail
+
+} // namespace rtc
--- a/ds3231/rtc.cpp
+++ b/ds3231/rtc.cpp
@@ -73,6 +73,11 @@
 #define TRUE 1
 #define FALSE 0

+#include "../clock.hpp"
+
+#include "../i2c/i2c.hpp"
+using i2c_t = i2c::I2c<i2c::Hardware<100'000>>;
+
 #include "rtc.h"

 #define RTC_ADDR 0x68 // I2C address
@@ -93,20 +98,23 @@ uint8_t bcd2dec(uint8_t b)

 uint8_t rtc_read_byte(uint8_t offset)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(offset);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(offset);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 1);
-	return twi_receive();
+	i2c_t::start<RTC_ADDR>(true);
+	const auto received = i2c_t::read<true>();
+	i2c_t::stop();
+
+	return received;
 }

 void rtc_write_byte(uint8_t b, uint8_t offset)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(offset);
-	twi_send_byte(b);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(offset);
+	i2c_t::write(b);
+	i2c_t::stop();
 }

 static bool s_is_ds1307 = false;
@@ -114,6 +122,8 @@ static bool s_is_ds3231 = false;

 void rtc_init(void)
 {
+	i2c_t::init();
+
 	// Attempt autodetection:
 	// 1) Read and save temperature register
 	// 2) Write a value to temperature register
@@ -153,17 +163,13 @@ struct rtc_tm* rtc_get_time(void)

 	// read 7 bytes starting from register 0
 	// sec, min, hour, day-of-week, date, month, year
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 7);
-
-	for (uint8_t i = 0; i < 7; i++) {
-		rtc[i] = twi_receive();
-	}
-
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(true);
+	i2c_t::readBytes<7>(rtc);
+	i2c_t::stop();

 	// Clear clock halt bit from read data
 	// This starts the clock for a DS1307, and has no effect for a DS3231
@@ -198,17 +204,13 @@ void rtc_get_time_s(uint8_t* hour, uint8_t* min, uint8_t* sec)

 	// read 7 bytes starting from register 0
 	// sec, min, hour, day-of-week, date, month, year
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 7);
-	
-	for(uint8_t i=0; i<7; i++) {
-		rtc[i] = twi_receive();
-	}
-	
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(true);
+	i2c_t::readBytes<7>(rtc);
+	i2c_t::stop();

 	if (sec)  *sec =  bcd2dec(rtc[0]);
 	if (min)  *min =  bcd2dec(rtc[1]);
@@ -218,8 +220,8 @@ void rtc_get_time_s(uint8_t* hour, uint8_t* min, uint8_t* sec)
 // fixme: support 12-hour mode for setting time
 void rtc_set_time(struct rtc_tm* tm_)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0);
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0);

 	uint8_t century;
 	if (tm_->year > 2000) {
@@ -231,28 +233,28 @@ void rtc_set_time(struct rtc_tm* tm_)
 	}

 	// clock halt bit is 7th bit of seconds: this is always cleared to start the clock
-	twi_send_byte(dec2bcd(tm_->sec)); // seconds
-	twi_send_byte(dec2bcd(tm_->min)); // minutes
-	twi_send_byte(dec2bcd(tm_->hour)); // hours
-	twi_send_byte(dec2bcd(tm_->wday)); // day of week
-	twi_send_byte(dec2bcd(tm_->mday)); // day
-	twi_send_byte(dec2bcd(tm_->mon) + century); // month
-	twi_send_byte(dec2bcd(tm_->year)); // year
+	i2c_t::write(dec2bcd(tm_->sec)); // seconds
+	i2c_t::write(dec2bcd(tm_->min)); // minutes
+	i2c_t::write(dec2bcd(tm_->hour)); // hours
+	i2c_t::write(dec2bcd(tm_->wday)); // day of week
+	i2c_t::write(dec2bcd(tm_->mday)); // day
+	i2c_t::write(dec2bcd(tm_->mon) + century); // month
+	i2c_t::write(dec2bcd(tm_->year)); // year

-	twi_end_transmission();
+	i2c_t::stop();
 }

 void rtc_set_time_s(uint8_t hour, uint8_t min, uint8_t sec)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0);
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0);

 	// clock halt bit is 7th bit of seconds: this is always cleared to start the clock
-	twi_send_byte(dec2bcd(sec)); // seconds
-	twi_send_byte(dec2bcd(min)); // minutes
-	twi_send_byte(dec2bcd(hour)); // hours
+	i2c_t::write(dec2bcd(sec)); // seconds
+	i2c_t::write(dec2bcd(min)); // minutes
+	i2c_t::write(dec2bcd(hour)); // hours

-	twi_end_transmission();
+	i2c_t::stop();
 }

 // DS1307 only (has no effect when run on DS3231)
@@ -296,16 +298,14 @@ void ds3231_get_temp_int(int8_t* i, uint8_t* f)

 	if (s_is_ds1307) return; // only valid on DS3231

-	twi_begin_transmission(RTC_ADDR);
+	i2c_t::start<RTC_ADDR>(false);
 	// temp registers 0x11 and 0x12
-	twi_send_byte(0x11);
-	twi_end_transmission();
+	i2c_t::write(0x11);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 2);
-
-	if (twi_available()) {
-		msb = twi_receive(); // integer part (in twos complement)
-		lsb = twi_receive(); // fraction part
+	i2c_t::start<RTC_ADDR>(true);
+	msb = i2c_t::read(); // integer part (in twos complement)
+	lsb = i2c_t::read<true>(); // fraction part

 	// integer part in entire byte
 	*i = msb;
@@ -315,38 +315,40 @@ void ds3231_get_temp_int(int8_t* i, uint8_t* f)
 	// float value can be read like so:
 	// float temp = ((((short)msb << 8) | (short)lsb) >> 6) / 4.0f;
 }
-}

 void rtc_force_temp_conversion(uint8_t block)
 {
 	if (s_is_ds1307) return; // only valid on DS3231

 	// read control register (0x0E)
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0E);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0E);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 1);
-	uint8_t ctrl = twi_receive();
+	i2c_t::start<RTC_ADDR>(true);
+	uint8_t ctrl = i2c_t::read<true>();
+	i2c_t::stop();

 	ctrl |= 0b00100000; // Set CONV bit

 	// write new control register value
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0E);
-	twi_send_byte(ctrl);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0E);
+	i2c_t::write(ctrl);
+	i2c_t::stop();

 	if (!block) return;

 	// Temp conversion is ready when control register becomes 0
 	do {
 		// Block until CONV is 0
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x0E);
-		twi_end_transmission();
-		twi_request_from(RTC_ADDR, 1);
-	} while ((twi_receive() & 0b00100000) != 0);
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x0E);
+		i2c_t::stop();
+
+		i2c_t::start<RTC_ADDR>(true);
+		// HACK: Missing stop after read, might still work though
+	} while ((i2c_t::read<true>() & 0b00100000) != 0);
 }


@@ -371,32 +373,35 @@ void rtc_set_sram(uint8_t *data)

 uint8_t rtc_get_sram_byte(uint8_t offset)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(DS1307_SRAM_ADDR + offset);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(DS1307_SRAM_ADDR + offset);
+	i2c_t::stop();

-	twi_request_from(RTC_ADDR, 1);
-	return twi_receive();
+	i2c_t::start<RTC_ADDR>(true);
+	const auto received = i2c_t::read<true>();
+	i2c_t::stop();
+	return received;
 }

 void rtc_set_sram_byte(uint8_t b, uint8_t offset)
 {
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(DS1307_SRAM_ADDR + offset);
-	twi_send_byte(b);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(DS1307_SRAM_ADDR + offset);
+	i2c_t::write(b);
+	i2c_t::stop();
 }

 void rtc_SQW_enable(bool enable)
 {
 	if (s_is_ds1307) {
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x07);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x07);
+		i2c_t::stop();

 		// read control
-   		twi_request_from(RTC_ADDR, 1);
-		uint8_t control = twi_receive();
+		i2c_t::start<RTC_ADDR>(true);
+		uint8_t control = i2c_t::read<true>();
+		i2c_t::stop();

 		if (enable)
 			control |=  0b00010000; // set SQWE to 1
@@ -404,20 +409,21 @@ void rtc_SQW_enable(bool enable)
 			control &= ~0b00010000; // set SQWE to 0

 		// write control back
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x07);
-		twi_send_byte(control);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x07);
+		i2c_t::write(control);
+		i2c_t::stop();

 	}
 	else { // DS3231
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x0E);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x0E);
+		i2c_t::stop();

 		// read control
-   		twi_request_from(RTC_ADDR, 1);
-		uint8_t control = twi_receive();
+		i2c_t::start<RTC_ADDR>(true);
+		uint8_t control = i2c_t::read<true>();
+		i2c_t::stop();

 		if (enable) {
 			control |=  0b01000000; // set BBSQW to 1
@@ -428,51 +434,53 @@ void rtc_SQW_enable(bool enable)
 		}

 		// write control back
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x0E);
-		twi_send_byte(control);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x0E);
+		i2c_t::write(control);
+		i2c_t::stop();
 	}
 }

 void rtc_SQW_set_freq(enum RTC_SQW_FREQ freq)
 {
 	if (s_is_ds1307) {
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x07);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x07);
+		i2c_t::stop();

 		// read control (uses bits 0 and 1)
-   		twi_request_from(RTC_ADDR, 1);
-		uint8_t control = twi_receive();
+		i2c_t::start<RTC_ADDR>(true);
+		uint8_t control = i2c_t::read<true>();
+		i2c_t::stop();

 		control &= ~0b00000011; // Set to 0
 		control |= freq; // Set freq bitmask

 		// write control back
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x07);
-		twi_send_byte(control);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x07);
+		i2c_t::write(control);
+		i2c_t::stop();

 	}
 	else { // DS3231
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x0E);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x0E);
+		i2c_t::stop();

 		// read control (uses bits 3 and 4)
-   		twi_request_from(RTC_ADDR, 1);
-		uint8_t control = twi_receive();
+		i2c_t::start<RTC_ADDR>(true);
+		uint8_t control = i2c_t::read<true>();
+		i2c_t::stop();

 		control &= ~0b00011000; // Set to 0
 		control |= (freq << 4); // Set freq bitmask

 		// write control back
-		twi_begin_transmission(RTC_ADDR);
-		twi_send_byte(0x0E);
-		twi_send_byte(control);
-		twi_end_transmission();
+		i2c_t::start<RTC_ADDR>(false);
+		i2c_t::write(0x0E);
+		i2c_t::write(control);
+		i2c_t::stop();
 	}
 }

@@ -480,13 +488,14 @@ void rtc_osc32kHz_enable(bool enable)
 {
 	if (!s_is_ds3231) return;

-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0F);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0F);
+	i2c_t::stop();

 	// read status
-	twi_request_from(RTC_ADDR, 1);
-	uint8_t status = twi_receive();
+	i2c_t::start<RTC_ADDR>(true);
+	uint8_t status = i2c_t::read<true>();
+	i2c_t::stop();

 	if (enable)
 		status |= 0b00001000; // set to 1
@@ -494,10 +503,10 @@ void rtc_osc32kHz_enable(bool enable)
 		status &= ~0b00001000; // Set to 0

 	// write status back
-	twi_begin_transmission(RTC_ADDR);
-	twi_send_byte(0x0F);
-	twi_send_byte(status);
-	twi_end_transmission();
+	i2c_t::start<RTC_ADDR>(false);
+	i2c_t::write(0x0F);
+	i2c_t::write(status);
+	i2c_t::stop();
 }

 // Alarm functionality
--- a/ds3231/rtc.h
+++ b/ds3231/rtc.h
@@ -18,7 +18,6 @@

 #include <stdbool.h>
 #include <avr/io.h>
-#include "twi.h"

 #define DS1307_SLAVE_ADDR 0b11010000
Author	SHA1	Message	Date
BlackMark	11211be9b9	Implement setting date-time	2020-05-16 17:25:00 +02:00
BlackMark	8c50aa4688	Implement setting time	2020-05-16 17:19:54 +02:00
BlackMark	a65b30f9df	Fix partial writing to only write to a range instead of until the end	2020-05-16 17:19:25 +02:00
BlackMark	cd5317db5b	Implement setting RTC date	2020-05-16 17:03:30 +02:00
BlackMark	92096b6101	Add helper to allow writing partial register data	2020-05-16 17:02:54 +02:00
BlackMark	80cce4671f	Implement optional automatic setting of day of week	2020-05-16 17:01:19 +02:00
BlackMark	c728d99f97	Fix default value for day field in time register	2020-05-16 16:59:54 +02:00
BlackMark	8e653ebd44	Add default init for registers	2020-05-16 16:00:27 +02:00
BlackMark	54b8917705	Implement modern C++ driver base	2020-05-15 19:47:44 +02:00
BlackMark	2768009720	Remove twi library and switch to i2c library submodule	2020-05-15 11:50:11 +02:00
BlackMark	04af54e7c8	Remove C time API glue from driver	2020-05-15 10:20:56 +02:00
BlackMark	9303fbf5b5	Fix clock path	2020-05-15 09:40:08 +02:00
BlackMark	727a974504	Fix warnings	2020-05-15 09:25:48 +02:00
BlackMark	b3364f0b88	Add gitignore, clang-format and license file	2020-05-15 09:20:23 +02:00
BlackMark	22a74d0b77	Imported changes from example branch	2017-12-17 10:55:25 +01:00
BlackMark	8e2e18128b	Exported code as submodule	2017-12-17 10:48:59 +01:00