MBus.cpp

/***
MBus.h - Library to emulate Alpine M-Bus commands

Copyright 2012 Oliver Mueller

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
#include "MBus.h"


MBus::MBus(uint8_t in, uint8_t out)
{
	_in=in;
	_out=out;
	
	pinMode(_in, INPUT);
	pinMode(_out,OUTPUT);
}

void MBus::sendZero()
{
	digitalWrite(_out, HIGH);
	delayMicroseconds(600);
	digitalWrite(_out, LOW);
	delayMicroseconds(2400);
}

void MBus::sendOne()
{
	digitalWrite(_out, HIGH);
	delayMicroseconds(1800);
	digitalWrite(_out, LOW);
	delayMicroseconds(1200);
}

void MBus::writeHexBitWise(uint8_t message)
{
		for(int8_t i=3; i>-1; i--)
	{
		uint8_t output=((message & (1<<i) )>>i);
		if(output==1)
		{
			sendOne();
		}
		else
		{
			sendZero();
		}
	}
}

boolean MBus::checkParity(uint64_t *message)
{
	uint8_t parity=0;
	uint8_t test=0;
	for(uint8_t i=16; i>0; i--)
	{
		test=((*message & ((uint64_t)0xF<<i*4) )>>i*4);
		parity=parity^test;
	}
	parity+=1;
	
	if(parity==(*message & ((uint64_t)0xF)))
		return true;
	else
	{
		return false;
	}
}

void MBus::send(uint64_t message)
{
	uint8_t printed=0;
	uint8_t parity=0;
	for(int8_t i=16; i>=0; i--)
	{
		uint8_t output=((message & ((uint64_t)0xF<<i*4) )>>i*4);
	parity=parity^output;
		if(!output&&!printed)
		{
			//do nothing
		}
		else
		{
			writeHexBitWise(output);
			printed++;
		}
	}
	parity+=1;
	writeHexBitWise(parity);
}

boolean MBus::receive(uint64_t *message)
{
	*message=0;
	if(digitalRead(_in)==LOW)
	{
		unsigned long time=micros();

		boolean gelesen=false; 
		uint8_t counter=0;

		while((micros()-time)<4000)
		{
			if(digitalRead(_in)==HIGH&&!gelesen)
			{
				if((micros()-time)<1400&&(micros()-time)>600)//0 is in between 600 and 1700 microseconds
				{
				  *message*=2;
				  counter++;
				  gelesen=true; 
				}
				else if((micros()-time)>1400)//1 is longer then 1700 microseconds
				{
				  *message*=2;
				  *message+=1;
				  counter++;
				  gelesen=true;
				  
				}
			}
			if(gelesen&&digitalRead(_in)==LOW)  
			{
				gelesen=false;
				time=micros();
			}  
		}
		if(counter%4||!checkParity(message)||counter==0)
		{
			//message is not ok
			*message=0;
					return false;
		}
		else
		{
			(*message)=(*message)>>4;//ingnore parity
					return true;
		}
	}
	return false;

}

/*
 CD-changer emulation from here on
*/
void MBus::sendPlayingTrack(uint8_t Track,uint16_t Time)
{
	uint64_t play=0x994000100000001ull;
	play|=(uint64_t)(Track%10)<<(10*4);
	play|=(uint64_t)(Track/10)<<(11*4);
	
	play|=(uint64_t)(Time%10)<<(4*4);
	play|=(uint64_t)((Time%100)/10)<<(5*4);
	play|=(uint64_t)((Time/60)%10)<<(6*4);
	play|=(uint64_t)(((Time/60)%100)/10)<<(7*4);
	
	send(play);
}

void MBus::sendChangedCD(uint8_t CD,uint8_t Track)
{
	uint64_t play=0x9B900000001ull;
	play|=(uint64_t)CD<<(7*4);
	play|=(uint64_t)(Track%10)<<(5*4);
	play|=(uint64_t)(Track/10)<<(6*4);
	send(play);
}

void MBus::sendCDStatus(uint8_t CD)
{
	uint64_t play=0x9C001999999Full;
	play|=(uint64_t)CD<<(9*4);
	send(play);
}