wrong positive and negative voltages on lcd 20x4


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  1. #1
    Join Date
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    Unhappy wrong positive and negative voltages on lcd 20x4

    I am in a symmetrical source project with pic 16f886, but in the proteus simulation the voltage values displayed on a 20x4 lcd, and these values are different from the registers in the proteus dc voltmeters.
    and the negative voltage displayed on the 20x4 lcd is displayed very fast.
    and the positive voltage displayed on the 20x4 lcd is displayed normal


    If someone could please review the code and correct it, I would appreciate it and thank you

    'Config for 16f886
    #CONFIG
    __config _CONFIG1, _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_ON & _LVP_OFF & _CP_ON & _CPD_ON
    #ENDCONFIG


    include "fp2032.bas"    ' Include file for 14-bit core with RAM at $20 (32-bit)
    define OSC 8
    DEFINE LCD_DREG PORTB
    DEFINE LCD_DBIT 4
    DEFINE LCD_RSREG PORTC
    DEFINE LCD_RSBIT 0
    DEFINE LCD_EREG PORTC
    DEFINE LCD_EBIT 1
    DEFINE LCD_BITS 4
    DEFINE LCD_LINES 2




    DEFINE ADC_BITS 10
    DEFINE ADC_CLOCK 3
    DEFINE ADC_ SAMPLEUS 50
    '************************************************* *******************
    LED VAR PORTC.4
    TXD VAR PORTC.6
    B1 VAR WORD
    B2 VAR WORD
    VALOR1 VAR BYTE
    VALOR2 VAR BYTE
    fpplaces var byte     ' Used to define number of decimal places in fpdisplay,fpdisplayr
    ahold var word     ' Required by fpdisplay
    bhold var word     ' Required by fpdisplay
    '************************************************* *******************
    INICIO:
    TRISC.6 = 0       'in
    TRISC.7 = 1       'out
    TRISA = 255       'Port_A = in
    ADCON1 = 000010   'left alignment
    TRISB.6 = 0       'out


    LCDOUT $FE,2," FUENTE SIMETRICA " '1_line
    LCDOUT $FE,$C0," JOSE LUIS COMAS LL " '2_line
    LCDOUT $FE,$94,"VOLT.NEGATIVO:-" '3_line
    LCDOUT $FE,$D4,"VOLT.POSITIVO:+" '4_line
    COMENZAR:
    ADCIN 1, B1 'read negativ via chanal_1_ADC
    ADCIN 2, B2 'read positiv via chanal_2_ADC

    'send ADC to terminal
    SEROUT2 TXD,188,["$", "$", DEC4 B1,"$", "$",DEC4 B2,10,13]

    aint = B1 'read -volt_to+B1
    gosub itofa 'Conviertelo a punto flotante
    bint = 2000 'Carga el valor 2000 (5*400)
    gosub itofb 'Conviertelo en punto flotante
    gosub fpmul 'ADCres * 2000
    bint = 52224 'Carga el valor de la cuenta maxima del ADC * 51
    gosub itofb 'Conviertelo en punto flotante
    GOSUB fpdiv '(ADCres * 2000)/52224
    '++++++++++++++
    'pv LCDOUT $FE,$A3," " 'Limpia el espacio donde se coloca el voltaje negativo
    LCDOUT $FE,$A3
    '++++++++++++++
    fpplaces = 2 : Gosub fpdisplayr ' Call display routine

    aint = B2 'Transfiere el valor del ADC del voltaje positivo
    gosub itofa 'Conviertelo a punto flotante
    bint = 35 'Carga el valor 35 (5*7)
    gosub itofb 'Conviertelo en punto flotante
    gosub fpmul 'ADCres * 35
    bint = 1024 'Carga el valor de la cuenta maxima del ADC
    gosub itofb 'Conviertelo en punto flotante
    GOSUB fpdiv '(ADCres * 35)/1024
    '++++++++++++++
    'pv LCDOUT $FE,$E3," " 'Limpia el espacio donde se coloca el voltaje positivo
    LCDOUT $FE,$E3
    '++++++++++++++
    fpplaces = 2 : Gosub fpdisplayr ' Call display routine


    HIGH LED
    GOTO COMENZAR

    ' The fpdisplayr routine checks for number of places, then adds the appropriate
    ' value to achieve rounding. To save RAM space, the values are hard coded
    ' in floating point format.


    fpdisplayr: If fpplaces=0 Then                  ' Set floating point barg to 0.5
                            bexp = $7E
                            bargb0 = $00
                            bargb1 = $00
                            bargb2 = $01
                      Endif
                      If fpplaces=1 Then                  ' Set floating point barg to 0.05
                            bexp = $7A
                            bargb0 = $4C
                            bargb1 = $CC
                            bargb2 = $CD
                      Endif
                      If fpplaces=2 Then                  ' Set floating point barg to 0.005
                            bexp = $77
                            bargb0 = $23
                            bargb1 = $D7
                            bargb2 = $0B
                      Endif
                      If fpplaces=3 Then                  ' Set floating point barg to 0.0005
                            bexp = $74
                            bargb0 = $03
                            bargb1 = $12
                            bargb2 = $6F
                      Endif
                      If fpplaces=4 Then                  ' Set floating point barg to 0.00005
                            bexp = $70
                            bargb0 = $51
                            bargb1 = $B7
                            bargb2 = $17
                      Endif


                      Gosub fpadd                         ' add barg to aarg
                      
    ' The fpdisplay routine outputs the signed value of aarg in decimal floating point format. It
    ' can display a positive value of 65535, and decimals to 4 places. The number of decimal
    ' places should be stored in fpplaces before calling the routine. The routine reads the
    ' floating point value of aarg. This value should NOT be converted to an integer before
    ' calling fpdisplay. The integer conversion will be perfomed as part of this routine, and
    ' aint will be returned to the calling program just as from the itofa routine.


    fpdisplay:  bexp = aexp                         ' Store the FP value of aarg to the barg variables
                      bargb0 = aargb0
                      bargb1 = aargb1
                      bargb2 = aargb2


                      Gosub ftoia                   ' Convert aarg to integer
                      ahold = aint                        ' Save this value for the final display
                      
                      Gosub itofa                   ' Convert integer back to float


                      Swap aexp,bexp                      ' Swap the FP values of aarg and barg before subtraction
                      Swap aargb0,bargb0
                      Swap aargb1,bargb1
                      Swap aargb2,bargb2


                      Gosub fpsub                   ' Subtract the integer portion from the full number




                      bint = 10                     ' Make bint = 10 E fpplaces
                      If fpplaces=2 Then
                            bint = 100
                      Endif
                      If fpplaces=3 Then
                            bint = 1000
                      Endif
                      If fpplaces=4 Then
                            bint = 10000
                      Endif


                      bhold = bint                        ' Save the integer value of bint for zeros loop


                      Gosub itofb                   ' Convert bint to integer prior to FP multiply
                      Gosub fpmul                   ' Multiply the decimal portion x 10 E fpplaces


                      Gosub ftoia                   ' Convert result to aint integer


                      Lcdout dec ahold              ' Display integer portion
                      If fpplaces > 0 Then                            
                            Lcdout "."              ' Display decimal point
    zeros:                  bhold = bhold / 10                                          ' Set bhold to be next place to right
                            If (aint < bhold) AND (bhold > 1) Then          ' Check for leading zero in decimal
                                  Lcdout "0"                                             ' Display leading zero
                                  Goto zeros                                            ' loop to check for another zero
                            Endif
                            Lcdout dec aint               ' Display the rest of the decimal portion
                      Endif


                      aint = ahold                        ' Restore the original value of aint


                      Return
    'pv LCDOUT $FE,$A3," " 'Limpia el espacio donde se coloca el voltaje negativo
    'pv LCDOUT $FE,$A3
    'pv LCDOUT $FE,$E3," " 'Limpia el espacio donde se coloca el voltaje positivo
    'pv LCDOUT $FE,$E3




    https://drive.google.com/file/d/11pN...uhMMrPdIk/view
    I attached a video link where you will see the code failure.


    You will see in the ldc 20x4 the negative voltage is displayed very quickly, the lcd will register voltage 12.45 and in the proteus dc voltmeter it registers 12.5V


    in the 20x4 lcd it registers a positive voltage of 12.58, it displays normal and in the dc voltmeter of proteus it will register a voltage of 12.6V.
    You will see that the decimals record different values of both positive and negative voltages.
    I hope that the video can serve you better to see and correct the code.
    thank you


    Last edited by josepic; - 20th April 2023 at 14:35.

  2. #2
    Join Date
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    Default Re: wrong positive and negative voltages on lcd 20x4

    What happend to this thread? ?
    https://www.picbasic.co.uk/forum/sho...989#post153989

    Ioannis

  3. #3
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    Default Re: wrong positive and negative voltages on lcd 20x4

    my take

    i doubt many would risk unvetted zipped content from google drive, youtube would be safer.


    what does displayed very fast mean ?


    what does displayed normal mean ?


    has it ever worked or is it just a proteus simulation, proteus does not really work for some real time things


    you could certainly fudge something up to correlate with proteus' measurements but it would be unlikely to work as precisely
    in reality and each unit manufactured would need individual code tweaking [hardly practical for production],as an academic exercise
    for students it may be useful to explain the differences between reality and simulated environment's






    there is no schematic.
    no voltage range given. no explanation of the analog input divider. why the pos rail uses a different divider to the neg rail
    no power supply


    why use fp ,can you really expect accuracy to 2 decimals.
    in a real situation you need to account for , reference accuracy/noise, conversion linearity / noise
    voltage divider accuracy and noise on the measured signal not to mention temperature effects
    you can easily mash out large numbers of decimals to display but their base accuracy cannot be justified




    what does symmetric power supply mean ,the code is just a display


    if its symmetric then why is +- different ? , over what range are we talking about




    two dp accuracy from single asynchronous adc results is not plausible afaics esp without a stable voltage reference for adc


    surely a lowpass filter is needed either electrical or software based , even oversampling could be employed
    and a temperature compensated voltage reference used if you really need that sort of precision



    op has remained steadfastly mute on any discussion on any points and just wants working code provided
    Warning I'm not a teacher

  4. #4
    Join Date
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    Default Re: wrong positive and negative voltages on lcd 20x4

    Quote Originally Posted by richard View Post
    ....

    op has remained steadfastly mute on any discussion on any points and just wants working code provided
    Then maybe chatGPT can give help!

    Ioannis

  5. #5
    Join Date
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    Default Re: wrong positive and negative voltages on lcd 20x4

    Then maybe chatGPT can give help
    interesting thought
    Warning I'm not a teacher

  6. #6
    Join Date
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    Cool Re: wrong positive and negative voltages on lcd 20x4

    Quote Originally Posted by richard View Post
    my take

    i doubt many would risk unvetted zipped content from google drive, youtube would be safer.


    what does displayed very fast mean ?


    what does displayed normal mean ?


    has it ever worked or is it just a proteus simulation, proteus does not really work for some real time things


    you could certainly fudge something up to correlate with proteus' measurements but it would be unlikely to work as precisely
    in reality and each unit manufactured would need individual code tweaking [hardly practical for production],as an academic exercise
    for students it may be useful to explain the differences between reality and simulated environment's






    there is no schematic.
    no voltage range given. no explanation of the analog input divider. why the pos rail uses a different divider to the neg rail
    no power supply


    why use fp ,can you really expect accuracy to 2 decimals.
    in a real situation you need to account for , reference accuracy/noise, conversion linearity / noise
    voltage divider accuracy and noise on the measured signal not to mention temperature effects
    you can easily mash out large numbers of decimals to display but their base accuracy cannot be justified




    what does symmetric power supply mean ,the code is just a display


    if its symmetric then why is +- different ? , over what range are we talking about




    two dp accuracy from single asynchronous adc results is not plausible afaics esp without a stable voltage reference for adc


    surely a lowpass filter is needed either electrical or software based , even oversampling could be employed
    and a temperature compensated voltage reference used if you really need that sort of precision



    op has remained steadfastly mute on any discussion on any points and just wants working code provided
    I have solved the problem, I attach image

  7. #7
    Join Date
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    Cool Re: wrong positive and negative voltages on lcd 20x4

    Name:  Simulacion Corregida Fuente Simetrica (1).jpg
Views: 5574
Size:  98.1 KB

    I have solved the problem, I attach image

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