Fancy bargraph on a HD44780 based LCD display

'Simple routine for a high-resolution bargraph on a HD44780 based LCD display.
'In this example, Input A0 is configured to read an input voltage between VSS and VDD 
'(usually 0...5V) and display the relative level as a bargraph where 5V equals full-scale
'reading. 


'The routine works as follows:
' - Prior to the while-wend loop, the LCD screens special character memory is programmed 
'   to enable the high-resolution readout
'
' - First a 10-bit ADC read occurs (value between 0....1023)
'
' - Then the calculations are done:
'       - First the value per segment (SUM byte) is calculated by multiplying the ADC read 
'         value with the maximum number of segments (in this case 16) and then divide it by
'         max read / number of scale lines per segment (1024 / 3)
'       - Then the number of full characters to display (FULL byte) is calculated  
'       - Finally the partial (PARTIAL byte) characters (0, 1 or 2) are calculated by extracting
'         the modulus of the restvalue

' - Finally, the result is displayed:
'       - First print the number of "FULL" characters
'       - Then print the "PARTIAL" character, which either is empty, 1 line or 2 lines
'       - Finally, clear the remaining segments to ensure that no old information still on the display 
'
' - And jump back to the beginning for a "real-time" readout
'
' Mischa van Santen (PA1OKZ) - Netherlands


'Config
Device = 16F88
                                       
Declare Xtal = 8
All_Digital true
Clear
                             
'Declare A/D convertor
Declare Adin_Res = 10                         ' 10-bit result
Declare Adin_Tad = FRC                        ' RC oscillator
Declare Adin_Stime = 50                       ' 50us sample time


'Variables
Dim SEGMENTS        As Byte                   ' Holds the number of segments of the display
Dim METER           As Word                   ' Holds A/D value for meter reading
Dim FULL            As Byte                   ' Holds the quantity of "full" characters to print |||
Dim PARTIAL         As Byte                   ' Holds the value 1, 2 or 3 for the partial character | or ||
Dim SUM             As Byte                   ' Holds the result of the sum (METER * 16)/341


'HD44780
DelayMS 10                                    ' Settle the display
Print $FE, $40                                ' HD44780 character program mode
Print $00, $00, $00, $15, $15, $15, $15, $15  ' Character 0: Three lines  |||
Print $00, $00, $00, $10, $10, $10, $10, $10  ' Character 1: One line     |
Print $00, $00, $00, $14, $14, $14, $14, $14  ' Character 2: Two lines    ||
Print $00, $00, $00, $00, $00, $00, $00, $00  ' Character 3: Scale         .


TRISA  = $01                                  ' PortA.0 = Input           
ANSELA = $01                                  ' PortA.0 = Analog 




'Main
SEGMENTS = 16                                 ' In this example we utilize a 16-segment display


While 1 = 1                                   ' Do it forever


'ADC reading
             DelayUS 20                       ' Charging time ADC
             METER = ADIn 0                   ' Pin 17 is ADC0 input @ 16F88


'Calculate meter reading
            SUM = (METER * SEGMENTS) / 341    ' Meter value. Value 341 = 1024 / 3 (values per segment)
            FULL = SUM / 3                    ' Number of full characters |||
            PARTIAL = SUM // 3                ' Modulus restvalue (0, 1 or 2)


'Display the bargraph          
            Print At 1, 1, Rep 0\FULL         ' Displays full characters ||| of the S-meter
            If PARTIAL > 0 Then Print PARTIAL ' Prints either the empty, | or || character
            Print Rep 3\SEGMENTS - FULL       ' Clears the remaining part of the level bar         


Wend
                
End