Need advice on A/D

[james]

Hello,

I am currently working on a project that consists of a Seconds Counter, 2 A/D inputs(1 for Temperature, 1 for monitoring battery voltage). The idea is to take the data and transmit via morse code. I have it all wired up to an 2x16 LCD display, and a piezo speaker until I can get everything running correctly. Currently using a PIC16F88 to test all of this, in the end I will be using a PIC12F675.

flow should be as follows
1)Read A/D
2)Turn on Tx
3)Send morsecode in this order: Counter, Temperature, Battery Voltage, and Identification
4)Turn off for 15sec
5)Repeat

My problem is, I am not so sure my A/D is working correctly.. my temperature displayed stays at 77degrees F. the voltage input to the processor is 3.16v Im using an LM335z which is calibrated at 10mv/K..and I know its not 109degree's F. more like 73 F...

I dont mean to come here and get all the answers, although I would love to get some constructive critizism. Not just about problem previously mentioned, but my coding in general..

Thanks in advance,
James



Code is as follows:

'Define LCD connections
'
Define  LCD_DREG        PORTB        'LCD data bits on PORTB   
Define  LCD_DBIT        0                'PORTB starting address
Define  LCD_RSREG       PORTB        'LCD RS bit on PORTB
Define  LCD_RSBIT       5               'LCD RS bit address
Define  LCD_EREG        PORTB        'LCD E bit on PORTB
Define  LCD_EBIT        4                'LCD E bit address
Define  LCD_BITS        4                'LCD in 4-bit mode
DEFINE  LCD_LINES       2               'LCD has 2 rows
    
' Define ADCIN parameters
'
Define OSC              8                   'Set oscillator at 8MHz
Define ADC_BITS         8                 'Set number of bits in result
Define ADC_CLOCK        3                'Set Clock source (3 = rc)
DEFINE ADC_SAMPLEUS     50           'Set sampling time in uS
CMCON = 7                                   'Turn comparators OFF

'------( Variables )------
'
tx          var byte                     'Transmitter variable
adval       var byte                    'A/D input for temperature
adval2      var byte                    'A/D input for . . . .
tempF       var byte                   'Result of A/D after temperature conversion
counter     var byte                    'Time variable
dit         var byte                       'for morse code "dot"
dah         var byte                       'for morse code "dash"
ditpause    var byte                     'for morse code pauses between letters/numbers
wordpause   var byte                    'Pause between words
i           var byte                          'Variable for subroutine
dig1        var byte                        'Variable for subroutine
dig2        var byte

'------( Registers )------
'             76543210
    TRISA  = %00000001                 'PortA.0 = input, all else = outputs
    TRISB  = %00000000                 'PortB = outputs
    OSCCON = %01110000               '
    ADCON0 = %01000001               'Make AN0 analog inputs, 
    ADCON1 = %00000000               'Format selection/divide clock                              
                                                 'Reference voltage = VDD
    ANSEL  = %00001001                'Sets all A/D off, except RA0 &

'------( Initialization )------
'
    
    dit       = 4                         'Length of dot in morse code(Lower number is Faster)
    dah       = dit * 3                 'Length of dash in morse code
    ditpause  = dit * 12              'Length of pause between dits & dahs in morse code
    wordpause = ditpause * 5      'Pause between letters/numbers
    counter   = 0                       'Clear time to 0
    Pause 18                             'Wait for LCD to initialize
    LCDOUT $FE, 2, "Loading..."     

'------( Main Code )------
'    
Loop:    
    
    pause 1000
    tx = 1
'PORTA.3 = 1  ' Tx ON
    counter = counter + 1            'Increment time
    
    ADCIN 0, adval                      'Read channel 0 - Temperature
    pause 20
    adcin 3, adval2                      'Read channel 3 - Battery Voltage
    tempf = adval / 10                 '
    Tempf = tempf - 273              '** Conversion from 10mV/K to Fahrenheit**
    TempF = Tempf * 9                '
    tempf = tempf / 5                  '
    tempf = tempf + 32                '      
    
    LCDout $FE, 1
    LCDOUT $FE, 2,$14,$14,$14,$14,$14,$14,$14,$14,$14, "A=", #adval2
    LCDOUT $FE, 2, "Cnt=", #counter                             
    Lcdout $FE, $C0, "F=", #tempf,$14,$14,$14,"ID:N3PX"

'------( Subroutine )------                           
'
for i = 2 to 0  step -1              '
    dig1 = counter dig i             'Subroutine to send out :Time
    gosub outdigit                    '
next i                               
     
pause 1000                           'Pause before sending next reading

for i = 2 to 0 step -1               '
    dig1 = tempf dig i               'Subroutine to send out :Temperature 
    gosub outdigit                    '
next i                              
          
pause 1000                           'Pause before sending next reading

for i = 2 to 0 step -1               '
    dig1 = adval2 dig i              'Subroutine to send out :Battery Monitor
    gosub outdigit                    '
next i                               

Pause 1000                           'Pause before sending Callsign

    gosub a                           '
    gosub num3                     'Subroutine to send out :Callsign
    gosub b                           '
    gosub c                           '

  tx = 0           
'PORTA.3 = 0 'Tx off
   
Pause 2000                      'Pause before recycling        

goto loop

outdigit:


Branchl dig1, [num0,num1,num2,num3,num4,num5,num6,num7,num8,num9]