' Name        : PULSEXT.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : PM or MPASM
' Target PIC  : PIC16F877-20, PIC18F452 or similar type
' Hardware    : LAB-XT Experimenter Board
' Oscillator  : 20MHz external
' Keywords    : DCD, HPWM, LCDOUT, LOOKUP, NCD, SELECT CASE
' Description : PICBASIC PRO sample program for dialing with pulses
' instead of DTMF. Works as a telephone, but doesn't detect incoming
' calls. See phone1xt.pbp for ring detect and ringer code. 
'

' MeLabs PIC programmer should not be connected to the ICSP header
' when running this code. It may interfere with the operation
' of the keypad.  

Define LOADER_USED 1  ' Only required for melabs Loader

Define OSC 20         ' Match the crystal on the board

' Define LCD registers and bits
Define LCD_DREG  PORTD
Define LCD_DBIT  4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG  PORTE
Define LCD_EBIT  1

sieze        Var PORTD.1   ' Relay control pin (sieze line)
loop_current Var PORTA.3   ' Loop current present (active low)

' Define program variables
h        Var Byte  ' Loop counter, misc
col      Var Byte  ' Keypad column
row      Var Byte  ' Keypad row
key      Var Byte  ' Key value
disp_key Var Byte  ' Key label

   TRISD = 0       ' Set PORTD to outputs
   PORTD = 0       ' Initialize PORTD, all zeros
   ADCON1 = 7      ' Set PORTA and PORTE to digital
   Pause 100       ' Wait for LCD to start up
   LCDOut $fe,1    ' Clear display
   OPTION_REG.7 = 0' Enable PORTB pullups (16F)
   'INTCON2.7 = 0   ' Enable PORTB pullups (18F)

initialize:
   key = $FF       ' Set key value to $FF (cleared)
   sieze = 0       ' Deactivate the line-sieze relay (Hang Up)
   Pause 250       ' Wait 250mS for line to settle
   LCDOut $fe, 1, "Press A for off-hook", $FE, $C0  ' Display sign-on message

mainloop:
   ' If Off Hook and the loop_current drops, Hang-Up the phone 
   ' and initialize variables.  
   IF (sieze = 1) AND (loop_current = 1) Then initialize
   GoSub getkey                 ' Check for user keypad entry
        
   Select Case key              ' Take action based on user keypad entry
          Case 12               ' User entry "A" - Off Hook
               sieze = 1        ' Activate sieze relay
               Pause 250        ' Pause 250mS to establish loop current
               LCDOut $FE, 1, "Press B to hang up", $FE, $C0 ' New prompt on LCD
               LCDOut $fe,$C0, "ready            ", disp_key ' Display user prompt

          Case 13,14,15         ' User entries "B", "C", "D" - Hang Up
               GoTo initialize  ' Hang Up and initialize variables

          Case Is < 12          ' User pressed number or *# key
               LCDOut $fe,$C0, "Dialing: ", disp_key ' Display key label on LCD
               IF sieze = 1 Then   ' If Off Hook, dial the digit
                  For h = 1 TO key ' Loop for each pulse
                    Pause 45       ' 45mS "Make" time
                    sieze = 0      ' Drop the line
                    Pause 65       ' 65mS "Break" time
                    sieze = 1      ' Sieze the line
                   Next h          ' Next pulse
                   Pause 300       ' Pause 300mS between digits
               EndIF
               LCDOut $fe,$C0, "ready            ", disp_key   ' Display user prompt
   End Select                      ' Continue program
   GoTo mainloop                   ' Repeat main loop

' Subroutine to get a key from keypad
getkey:
   ' Check for keypress
   For row = 0 TO 3      ' Loop for 4 rows in keypad
     PORTB = 0           ' All output pins low
     TRISB = ~(DCD row)  ' Set one row pin to output
     '@ NOP              ' Fudge for 18F452
     col = PORTB >> 4    ' Read column pins

     IF col != $0F Then  ' Check if key is pressed
        HPwm 1,127,7500  ' Begin speaker tick
        GoTo gotkey      ' If any keydown, exit
     EndIF
   Next row              ' Repeat for the next row
   key = $FF             ' No keys down, set key to $FF
   Return                ' Return to main loop
        
gotkey:                  ' Change row and column to key number 0 - 15
   Pause 15              ' Debounce
   HPwm 1,0,0            ' End speaker tick
        
   ' Wait for all keys up
   PORTB = 0               ' All output pins low
   TRISB = $F0             ' Least significant 4 pins out, top 4 pins in
   IF ((PORTB >> 4) != $0F) Then gotkey    ' If any keys down, loop
   key = (row * 4) + (NCD (col^$0F)) - 1   ' Combine row and column into numeric value
          
   ' Translate key to display label:
   ' 1  2  3  A
   ' 4  5  6  B
   ' 7  8  9  C
   ' *  0  #  D
   LookUp key,["123A456B789C*0#D"],disp_key
        
   ' Translate key to pulse dial value (* and # are invalid)
   ' 1   2   3   12
   ' 4   5   6   13
   ' 7   8   9   14
   ' 0   10  0   15
   LookUp key,[1,2,3,12,4,5,6,13,7,8,9,14,0,10,0,15],key     
   Return          ' Return to main loop

   End