Problems with analog converter in simulationboard in schoolproject of 6th grade


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  1. #1
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    Default Problems with analog converter in simulationboard in schoolproject of 6th grade

    Hello, I’m Nick. Before I say my problems I will first explain the meaning of the project. Or you can just skip and go to Problems.
    My mother language is Dutch so it’s possible that I write some faults.

    Meanings of project:
    We must build a bio-diesel mixing installation for our last year project and we are simulating the signals and rotating pumps with LED's so people can get a better view of the project and how the system works. The installation haves 3 output hoses for the mixed fuel and the ratio can be set with a BCD switch that is connected with the PLC that controls the pumps. A flow meter gives feedback to the PLC so he can control the pumps.

    In the simulation:
    The pump signal (0 to 10Volts) will go to the simulation board that returns a signal (of the flow control, 4-20mA) to the PLC, this signal will be lower than the input signal to simulate the resistance in the hoses depending on the selected hose. (When the Fault1 button is pressed down this will simulate an obstruction in the hose so the output signal will drop whit 90% of the input signal.)

    Problems:
    I'm having problems with programming the PIC. The biggest problem is using the AD-converter, the resolution of the converted has been set to an 8-bit resolution but I'm still getting a 2-bit resolution. How can I solve this problem?

    Code of analog input on Master:
    Code:
    Device 16F877A
    Config wdt_off, lvp_off, hs_osc, pwrte_on
    XTAL = 20
    
    '#####################################
    '############# Settings ##############
    '#####################################
    
    'analog settings
    Declare ADIN_RES 8          ' 8-bit result
    Declare ADIN_TAD FRC        ' RC OSC 
    Declare ADIN_STIME 50
    Declare CCP1_PIN PORTC.2
    Declare CCP2_PIN PORTC.1
    
    '         76543210
    ADCON1  = %10001101          ' AN0, AN1, VRef-, VRef+, RA5, RE0, RE1 en RE2
    TRISA   = %00001111          ' 4 analog inputs and 2 outputs for controlLED
    PORTA   = %00010000          ' controlLED red (when starting)
    TRISB   = %00110100          ' RB5, RB4 en RB2 are simulation controls
    PORTB   = %00000000
    TRISC   = %01001001          ' RC7(RX)o, RC6(TX)i, RC5(K1)o, RC4(K2)o, RC3i, RC2(conv 0-5V -> 4-20mA)o, RC1(conv 0-5V -> 4-20mA)o en RC0i
    PORTC   = %00000000
    TRISD   = %00000000          ' outputs to counters
    PORTD   = %10101010          ' makes all resets of counters high
    TRISE   = %00000111          ' inputs for the choice between the tree hoses
    PORTE   = %00000000
    
    '#####################################
    '############## Aliases ##############
    '#####################################
    
    'analog inputs
    Symbol AIDsl    = PORTA.0   ' analog input   \
    Symbol AnDsl    = 0         ' analog channel  > of diesel
    Dim    MBDsl    As Byte     ' analog value   /
    Symbol AIBio    = PORTA.1   ' analog input   \
    Symbol AnBio    = 1         ' analog channel  > of bio
    Dim    MBBio    As Byte     ' analog value   /

  2. #2
    Join Date
    Nov 2003
    Location
    Wellton, U.S.A.
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    Hi Nick,

    That is quite a project.

    It looks like you are using Proton Basic though. If you are you will receive better help here
    http://www.picbasic.org/
    If I am wrong post back and let us know...
    Dave
    Always wear safety glasses while programming.

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