RH/Temp Sensor Example Code

[Bruce]

Someone asked me a few questions recently on using one of these new RH/Temp sensors, so,
of course, I had to have one to mess with & grabbed one for testing.

These are really nice little units for anyone looking to measure relative humidity & temperature.

http://www.preconusa.com/humidity_mo...ew_sensors.htm

I thought someone here may find some use for portions of a test routine I put together, so here it is.

  ' MPASMWIN V5.02 assembler. PBP V2.46a 674 words.
    DEFINE  LOADER_USED 1
    DEFINE  OSC 4
    DEFINE  HSER_TXSTA 24H ' TX enabled, 8-bit, BRGH=1 for high-speed
    DEFINE  HSER_SPBRG 25  ' Set baud rate generator for 9600bps @4MHz
    DEFINE  HSER_RCSTA 90H ' USART enabled, 8-bit, continuous receive
    TEMP    VAR BYTE[12]   ' Array for sensor data
    SIGN    VAR TEMP(7)    ' Alias to TEMP(7). Sensors ± temp sign bit location
    RESULTF VAR WORD       ' For °C to °F conversion
    DEG     CON 176        ' ASCII ° symbol for degrees
    NegC    CON "-"        ' -°C is represented by the ASCII "-" symbol
    ' Note: Positive temp is represented by an ASCII space
    ' Sensor output = 9600bps ASCII format as: H xx.x T±xx.x CR

    ' Program serial output 9600bps ASCII format: RH=11.5% : TEMP=21.8°C : 71.24°F
MAIN:
    PAUSE 1000  ' Let everything initialize & delay between display updates
    
    ' Synch with HS-200DD RH/Temp sensor ASCII H character output
    SERIN2 PORTB.0,84,[WAIT("H"),STR TEMP\12] ' HS-2000DD input on RB0
    
    ' Parse & display relative humidity reading from HS-200DD sensor
    HSEROUT ["RH=",TEMP(1),TEMP(2),TEMP(3),TEMP(4),"% : "]
    
    ' Parse & display temperature reading from HS-2000DD sensor
    HSEROUT ["TEMP=",TEMP(8),TEMP(9),TEMP(10),TEMP(11),DEG,"C : "]
    
    ' Parse & remove ASCII component & build whole integer number
    RESULTF = ((TEMP(8)-48)*100)+((TEMP(9)-48)*10)+(TEMP(11)-48)
    
    ' I.E. ASCII temp "24.9" now = 249d for a useable whole integer number.

    ' Now take ((resultf * 18)/100)+32 for whole number, and resultf // 100
    ' for the remainder.
    
    ' Example: 41.0°C = 105.8°F. ((410*18)/100)+32 = whole the number result.
    ' 7,380/100 = 73. We're dropping the .8 and adding 73 + 32 for 105.
    ' Then with RESULTF//100 we end up with 8 as the remainder for 105.8°F
     
    RESULTF = RESULTF * 18        ' °C * 9/5
    IF Sign = NegC THEN Negative  ' If -°C jump to -result handler
    
    ' This handles everything from 99.9°C (211.82°F) to 00.0°C (32.0°F)
    HSEROUT [DEC (RESULTF/100)+32,".",DEC2 RESULTF//100,DEG,"F",13,10]
    GOTO MAIN
          
Negative:
    ' The first section handles everything from -00.1°C (31.82°F) to -17.7°C (0.14°F)
    ' which is still +°F.
    IF RESULTF < 3200 THEN
       HSEROUT [DEC (3200-RESULTF)/100,".",DEC2 (3200-RESULTF)//100,DEG,"F",13,10]
    ELSE
    ' The 2nd section handles everything from -17.8°C (-0.04°F) to -99.9°C (-147.82°F)
    ' Note how we reverse the subtraction here on -°F.
       HSEROUT ["-",DEC (RESULTF-3200)/100,".",DEC2 (RESULTF-3200)//100,DEG,"F",13,10]
    ENDIF
    GOTO MAIN
       
    END

And if you don't have one of these nifty gadgets, but would like to run the conversion routines with a
serial terminal emulator, here's a chopped version;

    DEFINE LOADER_USED 1
    DEFINE OSC 4
    DEFINE  HSER_TXSTA 24H ' TX enabled, 8-bit, BRGH=1 for high-speed
    DEFINE  HSER_SPBRG 25  ' Set baud rate generator for 9600bps @4MHz
    DEFINE  HSER_RCSTA 90H ' USART enabled, 8-bit, continuous receive
    TEMP    VAR BYTE(5)    ' Array for simulated sensor temp input
    RESULTF VAR WORD       ' For °C to °F conversion
    DEG     CON 176        ' ASCII value for ° symbol
    SIGN    VAR TEMP(0)    ' TEMP(0) holds the sign indicator
    NEG     CON "-"        ' Negative °C indicator
                           ' Positive °C indicator = " " ASCII space
   
    HSEROUT ["Input H then +xx.x or -xx.x temp to convert",13,10]
    ' Enter H-19.7 for the conversion result of -19.7°C to °F
    
Main:
    HSERIN [WAIT("H"),STR TEMP\5]
    HSEROUT [TEMP(0),TEMP(1),TEMP(2),TEMP(3),TEMP(4),DEG,"C = "]
    ' Temp input to convert starts at TEMP(1). TEMP(0) = sign indicator
    ' TEMP(3) is the decimal point
    RESULTF = ((TEMP(1)-48)*100)+((TEMP(2)-48)*10)+(TEMP(4)-48)
    GOSUB Test
    GOTO Main

Test: 
    ' This handles everything from 00.0°C (32.0°F) to 99.9°C (211.82°F)
    RESULTF = RESULTF * 18  ' °F = (1.8*°C)+32
    IF Sign = NEG THEN Negative
    HSEROUT [DEC (RESULTF/100)+32,".",DEC2 RESULTF//100,DEG,"F",13,10]
    RETURN
          
Negative:
    ' The first section handles everything from -00.1°C (31.82°F) to -17.7°C (0.14°F)
    IF RESULTF < 3200 THEN
       HSEROUT [DEC (3200-RESULTF)/100,".",DEC2 (3200-RESULTF)//100,DEG,"F",13,10]
    ELSE
    ' The 2nd section handles everything from -17.8°C (-0.04°F) to -99.9°C (-147.82°F)
       HSEROUT ["-",DEC (RESULTF-3200)/100,".",DEC2 (RESULTF-3200)//100,DEG,"F",13,10]
    ENDIF
    RETURN
    
    END

Enter H+69.9 to view the °C to °F conversion for 69.9°C to °F.
Enter H-69.9 to see the result of -69.9°C to °F.

It should work for °C to °F conversion of values from 99.9°C to -99.9°C.