16F616 A to D


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  1. #1

    Default 16F616 A to D

    I can't seem to get the A/D to work correctly. I have tried different configs yet no luck. The pin I am using to measure voltage is RC0/AN4/C2IN+. So I configure the pin to analogue with ANSEL.4=1, disable the comparator with CM2CON0.7=0 and select the analogue bit with ADCON0.5-2.

    I check voltage at the pin with my scope and its .650v. Yet debugging I get a value of '0' with any input from 0-5v. Any input is appreciated.

    Code:
    INCLUDE "modedefs.bas"
      
    FF           var PortC.0
    FrontOut     var PortC.1
    RearOut      var PortC.2
    
    Voltage      var word
    Perfect      var word
    
    define OSC 20
    DEFINE DEBUG_REG PortC          'SET DEBUG PIN PORT
    DEFINE DEBUG_BIT 5             'SET DEBUG PIN BIT
    DEFINE DEBUG_BAUD 9600         'SET DEBUG BAUD RATE
    DEFINE DEBUG_MODE 1            'SET DEBUG MODE 0=TRUE / 1=INVERTED
    
    Define ADC_BITS 10 ' Set number of bits in result
    Define ADC_CLOCK 3 ' Set clock source (3=rc)
    Define ADC_SAMPLEUS 10 ' Set sampling time in uSec
    
    TRISC.0 = 1  'FF (Flip/Flop)
    TRISC.1 = 0  'FrontOut
    TRISC.2 = 0  'RearOut
    
    '0 Digital 1 Analogue
    ANSEL.6=0 'RearOut
    ANSEL.5=0 'FrontOut
    ANSEL.4=1 'FF 
    
    CM2CON0.7=0 'Disable comparator
    
    ADCON0.7=1 'Right Justified
    ADCON0.6=0 ''Voltage reference is VDD
    ADCON0.5=0 'Turns on AN4 to analogue
    ADCON0.4=1
    ADCON0.3=0
    ADCON0.2=0
    ADCON0.0=1
    
    Perfect = 512
    
    Loop:
      GOSUB Get_Voltage
      gOSUB Compare
      debug "Voltage=", DEC VOltage, cr
    Goto Loop
    
    Get_Voltage:
    ADCIN FF, Voltage
    Return
    
    Compare:
    If Voltage < Perfect then
       Low FrontOut
    endif
    
    If Voltage > Perfect then
       Low RearOut
    endif
    Return

  2. #2
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    You have capture compare registers to deal with, and others. CCP1CON, CM1CON0,CM2CON0, CM2CON1, ADCON1
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  3. #3


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    Default

    Am I doing the ADCON0.x correctly?

    I added CM1CON0.7=0 so both comparators are disabled.

    I still get Voltage=0 when I debug.

    INCLUDE "modedefs.bas"

    FF var PortC.0
    FrontOut var PortC.1
    RearOut var PortC.2

    Voltage var word
    Perfect var word

    define OSC 20
    DEFINE DEBUG_REG PortC
    DEFINE DEBUG_BIT 5
    DEFINE DEBUG_BAUD 9600
    DEFINE DEBUG_MODE 1

    Define ADC_BITS 10
    Define ADC_CLOCK 3
    Define ADC_SAMPLEUS 10

    TRISC.0 = 1 'FF (Flip/Flop)
    TRISC.1 = 0 'FrontOut
    TRISC.2 = 0 'RearOut

    '0 Digital 1 Analogue
    ANSEL.6=0 'RearOut
    ANSEL.5=0 'FrontOut
    ANSEL.4=1 'FF
    CM1CON0.7=0
    CM2CON0.7=0 'Disable comparator

    ADCON0.7=1 'Right Justified
    ADCON0.6=0 'Voltage reference is VDD
    ADCON0.5=0 'Turns on AN4 to analogue
    ADCON0.4=1
    ADCON0.3=0
    ADCON0.2=0
    ADCON0.0=1

    CCP1CON.3=0
    CCP1CON.2=0
    CCP1CON.1=0
    CCP1CON.0=0

    Perfect = 512

    Loop:
    GOSUB Get_Voltage
    gOSUB Compare
    debug "Voltage=", DEC VOltage, cr
    Goto Loop

    Get_Voltage:
    ADCIN FF, Voltage
    Return

    Compare:
    If Voltage < Perfect then
    Low FrontOut
    endif

    If Voltage > Perfect then
    Low RearOut
    endif
    Return


  4. #4
    Join Date
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    Default

    When you use ADCIN you must use the Channel #, not the PORT pin name.

    Code:
    ADCIN 4, Voltage ' PORTC.0 = AN4
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

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