DS 1822 programming help
Archiver
Posts: 46,084
Dear all,
I'm writing a program for temperature sensing with the use of
DS1822. A sample program from web is listed below. In the program,
there is a "owin" command, (OWIN 0,2,
[noparse][[/noparse]Temp.LOWBYTE,Temp.HIGHBYTE,CRem,CRem,CRem,CRem,CRem,CPerC]). Does
anyone know that why there are so many "CRem"? what's the use of
those "CRem". I am quite confused and don't understand this command.
Besides, for the operation of DS 1822 with Basic Stamp, the stamp
should 1)issue skip ROM command, 2)issue write scratchpad command, 3)
sends three data bytes to scratchpad (TH, TL, and config). Can
anyone teach me how to convert this three command into PBasic
language????
I really have no idea. Please....
Thank all very much!!!
' Thermometer chip using the BS2p's 1-wire commands. Connect the
BS2p
to
the DS1820 as
' shown in the diagram in the OWIN or OWOUT command description.
' This code reads the Counts Remaing and Counts per Degree C
registers
in
the DS1820
' chip in order to provide a more accurate temperature reading (down
to
1/100th of a
' degree). It also calculates degrees Fahrenheit. NOTE: The
algebraic
equations used
' will not work properly with negative temperatures.
'{$STAMP BS2p} 'STAMP directive (specifies a BS2p)
Temp VAR Word 'Holds the temperature value
CRem VAR Byte 'Holds the counts remaining value
CPerC VAR Byte 'Holds the Counts per degree C value
Start:
OWOUT 0,1,[noparse][[/noparse]$CC,$4E,$96,$00,$7F]
OWOUT 0,1,[noparse][[/noparse]$CC,$44] 'Send Calculate Temperature command
CheckForDone: 'Wait until conversion is done
PAUSE 25
OWIN 0,4,[noparse][[/noparse]Temp] 'Here we just keep reading low pulses until
IF Temp = 0 THEN CheckForDone 'the DS1820 is done, then it returns
high.
OWOUT 0,1,[noparse][[/noparse]$CC,$BE] 'Send Read ScratchPad command
OWIN 0,2,
[noparse][[/noparse]Temp.LOWBYTE,Temp.HIGHBYTE,CRem,CRem,CRem,CRem,CRem,CPerC]
'Calculate temperature in degrees C
DEBUG ?Temp,?CRem,?CPerC,CR
Temp = Temp>>1*100-25+((CPerC*100-(CRem*100))/CPerC)
DEBUG ?Temp,CR
'DEBUG HOME,DEC3 Temp/100,".",DEC2 Temp-(Temp/100*100)," C",CR
DEBUG DEC3 Temp/1000,".",DEC2 Temp-(Temp/100*100)," C",CR
'Calculate temperature in degrees F
'Temp = Temp*/461+3200
'DEBUG DEC3 Temp/100,".",DEC2 Temp-(Temp/100*100)," F"
GOTO Start
I'm writing a program for temperature sensing with the use of
DS1822. A sample program from web is listed below. In the program,
there is a "owin" command, (OWIN 0,2,
[noparse][[/noparse]Temp.LOWBYTE,Temp.HIGHBYTE,CRem,CRem,CRem,CRem,CRem,CPerC]). Does
anyone know that why there are so many "CRem"? what's the use of
those "CRem". I am quite confused and don't understand this command.
Besides, for the operation of DS 1822 with Basic Stamp, the stamp
should 1)issue skip ROM command, 2)issue write scratchpad command, 3)
sends three data bytes to scratchpad (TH, TL, and config). Can
anyone teach me how to convert this three command into PBasic
language????
I really have no idea. Please....
Thank all very much!!!
' Thermometer chip using the BS2p's 1-wire commands. Connect the
BS2p
to
the DS1820 as
' shown in the diagram in the OWIN or OWOUT command description.
' This code reads the Counts Remaing and Counts per Degree C
registers
in
the DS1820
' chip in order to provide a more accurate temperature reading (down
to
1/100th of a
' degree). It also calculates degrees Fahrenheit. NOTE: The
algebraic
equations used
' will not work properly with negative temperatures.
'{$STAMP BS2p} 'STAMP directive (specifies a BS2p)
Temp VAR Word 'Holds the temperature value
CRem VAR Byte 'Holds the counts remaining value
CPerC VAR Byte 'Holds the Counts per degree C value
Start:
OWOUT 0,1,[noparse][[/noparse]$CC,$4E,$96,$00,$7F]
OWOUT 0,1,[noparse][[/noparse]$CC,$44] 'Send Calculate Temperature command
CheckForDone: 'Wait until conversion is done
PAUSE 25
OWIN 0,4,[noparse][[/noparse]Temp] 'Here we just keep reading low pulses until
IF Temp = 0 THEN CheckForDone 'the DS1820 is done, then it returns
high.
OWOUT 0,1,[noparse][[/noparse]$CC,$BE] 'Send Read ScratchPad command
OWIN 0,2,
[noparse][[/noparse]Temp.LOWBYTE,Temp.HIGHBYTE,CRem,CRem,CRem,CRem,CRem,CPerC]
'Calculate temperature in degrees C
DEBUG ?Temp,?CRem,?CPerC,CR
Temp = Temp>>1*100-25+((CPerC*100-(CRem*100))/CPerC)
DEBUG ?Temp,CR
'DEBUG HOME,DEC3 Temp/100,".",DEC2 Temp-(Temp/100*100)," C",CR
DEBUG DEC3 Temp/1000,".",DEC2 Temp-(Temp/100*100)," C",CR
'Calculate temperature in degrees F
'Temp = Temp*/461+3200
'DEBUG DEC3 Temp/100,".",DEC2 Temp-(Temp/100*100)," F"
GOTO Start