Temprature conversion --- C to F

[Heckler]

I feel your pain!! the math was WAY over my head also... luck was in my favor and I stumbled across an INCLUDE file by Darrel Taylor. His routine will convert between C, F, Kelvin and possibly more!!!

Here is my temperature conversion... after reading a DS18B20 one wire temp sensor.

bear in mind that this routine is for a One Wire DS18b20 temp sensor... and the value is a two BYTE value that can be programmed for 9-12 bit resolution and the value is initially read in deg C

'=======TEMPERATURE subroutine==============================================
ShowTemp:
    while PortA.3=0 : wend
    PAUSE 500
    OWOUT  Comm_Pin, 1, [$CC, $4E, 0, 0, DS18B20_9bit]  'set resolution of sensor
Start_Convert:
    OWOUT  Comm_Pin, 1, [$CC, $44]' Skip ROM search & do temp conversion

Wait_Up:
    OWIN   Comm_Pin, 4, [Busy]    ' Read busy-bit
    IF     Busy = 0 THEN Wait_Up  ' Still busy..?, Wait_Up..!
    OWOUT  Comm_Pin, 1, [$CC, $BE]' Skip ROM search & read scratchpad memory
    OWIN   Comm_Pin, 2, [Raw.LOWBYTE, Raw.HIGHBYTE]' Read two bytes / end comms
Convert_Temp:
    Sign="+"
    IF Cold_Bit = 1 THEN    'it's below zero Celsius
    C=(ABS Raw>>4)*-10      'so shift the ABS value right and mult X -10
    ELSE
    C=(Raw>>4)*10           'else shift value right and mult X 10
    ENDIF

@ CtoF _C, _F             ; Convert Celsius to Fahrenheit
        'converted value will be X 10, ie. 756=75.6 deg F
        'so devide by 10 to get whole degrees

    IF f.15=1 THEN Sign="-" 'if converted value is below zero F then sign is "-"
    TempF = (ABS f)/10      'take tha ABS value and /10
    IF f//10 >4 THEN TempF=TempF+1 'check remainder, if >4 then round up

    IF TempF <10 THEN         '1 digit value plus "deg F"
        len=3
    elseif TempF <100 THEN    '2 digit value plus "deg F"
        len=4
    ELSE                      '3 digit value plus "deg F"
        len=5
    ENDIF
    arraywrite msg,[Sign,DEC TempF,"*"] ' *= lookup for "deg F"
    GOSUB Message                       ' display current temp

if intrpt=1 then SleepNow  'if here by interrupt then return to SleepNow
IF mode=0 THEN Motto        'if here from motto return to motto 
GOTO Icon                   'else return to icon

Here are most of the variables associated with the temp conversion routine.

'-------------[variables and constants for temperature routine]--------------
DS18B20_9bit  CON 011111   ' set resolution on DS18B20 93.75ms, 0.5 C
Comm_Pin      VAR   PortA.4   ' One-wire Data-Pin "DQ" on PortA.4
Busy          VAR BIT         ' Busy Status-Bit
Raw           VAR   WORD      ' RAW Temperature readings
TempF         VAR WORD        ' Temp in deg F
Cold_Bit      VAR Raw.BIT11   ' Sign-Bit for +/- Temp. 1 = Below 0 deg C
Sign          VAR BYTE        ' +/- sign for temp display

Don't forget to add this line to your program...

INCLUDE "Temp_Convert_CtoFonly.pbp"

also you will need to delete the .txt extension off from the attached include file.

I hope this helps... ask questions if you need to.

possibly most if what you need is Darrels (as always excellent) include file.