wrong positive and negative voltages on lcd 20x4

[HenrikOlsson]

I think you gonna have to post the code, otherwise it's kind of hard...

[josepic]

'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 = %11000010   '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

thanks for answering
I attach the code

[josepic]

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