temp.c

myTemp is used to connect PalmOS PDAs to Dallas Microlan(tm) Devices. It currently supports DS1820

/*
  myTemp is used to connect PalmOS PDAs to Dallas Microlan(tm) Devices
  It currently supports DS1820/DS18S20 Digital Thermometers
  Copyright (C) 2000 Christof Klaiber

  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 2 of the License, or 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, write to the Free Software Foundation, Inc., 59 Temple
  Place, Suite 330, Boston, MA  02111-1307  USA


  Christof Klaiber <[e-mail]>
  Lachnerstr. 22
  76131 Karlsruhe
  Germany
*/

#include <PalmOS.h>
#include <SerialMgrOld.h>
#include "com.h"
#include "temp.h"
#include "ds1820.h"

/*
	Name:		TempConvertTemp
	Purpose:	compute the temperature from the values read from sensor
	Input:		Int16*	temp	<out>	temperature
				UInt8	scratchPad[kScratchPadLength]	the nine values read from the sensor's scratchpad
	Result:		error
	Name:		Christof Klaiber <[e-mail]>
	Versions:	11.12.2003	introduced
				12.12.2003	error handling
*/
UInt32	TempConvertTemp(Int16*, UInt8[kScratchPadLength]);

UInt32 TempGetTemp(Int16* temp, UInt32* state, UInt16* serialRefNum)
{
	Err err = 0;
	UInt32	tempErr = tempNoError;
	UInt8	scratchPad[kScratchPadLength];
	
	switch (*state)
	{
	case OpenSerialState:
      	err = SysLibFind("Serial Library", serialRefNum);
      	if(err == sysErrLibNotFound )
		{
        	err = SysLibLoad('libr', 'swrp', serialRefNum);
      	}
		if (err)
		{
			tempErr = tempSerErrLibCantLoad;
			break;
		}
		
		err = SerOpen(*serialRefNum, 0, 115200);
		if (err)
		{
			if(err == serErrAlreadyOpen)
			{
				SerClose(*serialRefNum);
				tempErr = serErrAlreadyOpen;
			}
			else
			{
				tempErr = tempSerErrCantOpen;
			}
			break;
		}
		*state = SkipRomForConvState;
		break;
		
/* falls through */		
	case SkipRomForConvState:
		tempErr = DSSkipROM(*serialRefNum);
		if (tempErr)
		{
			break;
		}
	case TempConvState:
		tempErr = DSReadTemperature(*serialRefNum);
		if (tempErr)
		{
			break;
		}
		*state = TempConvResetState;
		break;

/* falls through */	
	case TempConvResetState:	
		tempErr = DSResetTemperature(*serialRefNum);
		if (tempErr)
		{
			break;
		}
/* falls through*/	
	case SkipRomForReadState:
		tempErr = DSSkipROM(*serialRefNum);
		if (tempErr)
		{
			break;
		}
	case ReadScratchpadState:	
		tempErr = DSReadScratchpad(*serialRefNum, scratchPad);
		if (tempErr)
		{
			break;
		}
		tempErr = TempConvertTemp(temp, scratchPad);
		if (tempErr)
		{
			break;
		}
		err = SerClose(*serialRefNum);
		if (err)
		{
			tempErr = tempSerErrCantClose;
			break;
		} else {
			*state = TempReadyState;
		}
		break;
	
	default:
		break;
	}
	
	if (tempErr && tempErr != tempSerErrCantClose)
	{
		err = SerClose(*serialRefNum);
		if (err)
		{
			tempErr = tempSerErrCantClose;
		}
	}
	
	return tempErr;
}

UInt32 TempConvertTemp(Int16* temp, UInt8 scratchPad[kScratchPadLength])
{
	UInt16	hiPrec;
	
	if (scratchPad[1] == 0)
	{
		*temp = scratchPad[0] >> 1;
	} else {
		*temp = -1 * (0x100 - scratchPad[0]) >> 1;
	}
	
	*temp *= 100;
	*temp -= 25;
	hiPrec = scratchPad[7] - scratchPad[6];
	hiPrec *= 100;
	
	if (!scratchPad[7])
	{
		return tempErrConvErr;
	}
	hiPrec /= scratchPad[7];
	*temp += hiPrec;
	
	return tempNoError;
}

UInt32	TempStopLogging(UInt32* state, UInt16* serialRefNum)
{
	UInt32	tempErr = tempNoError;
	Err		err;
	
	if (*state != TempReadyState && *state != OpenSerialState)
	{
		err = SerClose(*serialRefNum);
		if (err)
		{
			tempErr = tempSerErrCantClose;
		} else {
			*state = OpenSerialState;
		}
	}
	return tempErr;
}