' ==============================================================================
'
'   File...... Ex11 - LCD Demo.BS2
'   Purpose... Essential LCD control
'   Author.... Parallax
'   E-mail.... stamptech@parallaxinc.com
'   Started...
'   Updated... 01 MAY 2002
'
'   {$STAMP BS2}
'
' ==============================================================================


' ------------------------------------------------------------------------------
' Program Description
' ------------------------------------------------------------------------------

' This program demonstrates essential character LCD control.
'
' The connections for this program conform to the BS2p LCDIN and LCDOUT
' commands.  Use this program for the BS2, BS2e or BS2sx.  There is a separate
' program for the BS2p.


' ------------------------------------------------------------------------------
' I/O Definitions
' ------------------------------------------------------------------------------

E               CON     8                       ' LCD Enable pin  (1 = enabled)
RS              CON     3                       ' Register Select (1 = char)
LCDbus          VAR     OUTB                    ' 4-bit LCD data bus
DQ              CON     0                       ' DS1620.1 (data I/O)
Clock           CON     1                       ' DS1620.2
Reset           CON     2                       ' DS1620.3


' ------------------------------------------------------------------------------
' Constants
' ------------------------------------------------------------------------------

ClrLCD          CON     $01                     ' clear the LCD
CrsrHm          CON     $02                     ' move cursor to home position
'CrsrLf          CON     $10                     ' move cursor left
'CrsrRt          CON     $14                     ' move cursor right
DispLf          CON     $18                     ' shift displayed chars left
DispRt          CON     $1C                     ' shift displayed chars right
DDRam           CON     $80                     ' Display Data RAM control
RdTmp           CON     $AA                     ' read temperature
WrHi            CON     $01                     ' write TH (high temp)
WrLo            CON     $02                     ' write TL (low temp)
RdHi            CON     $A1                     ' read TH
RdLo            CON     $A2                     ' read TL
StartC          CON     $EE                     ' start conversion
StopC           CON     $22                     ' stop conversion
WrCfg           CON     $0C                     ' write config register
RdCfg           CON     $AC                     ' read config register


' ------------------------------------------------------------------------------
' Variables
' ------------------------------------------------------------------------------

char            VAR     BYTE                    ' character sent to LCD
index           VAR     BYTE                    ' loop counter
tempIn          VAR     WORD                    ' raw temperature
sign            VAR     tempIn.BIT8             ' 1 = negative temperature
tSign           VAR     BIT
tempC           VAR     WORD                    ' Celsius
tempF           VAR     WORD                    ' Fahrenheit


' ------------------------------------------------------------------------------
' EEPROM Data
' ------------------------------------------------------------------------------

Msg             DATA    "THE BASIC STAMP!", 0   ' preload EEPROM with message


' ------------------------------------------------------------------------------
' Initialization
' ------------------------------------------------------------------------------

Initialize:
  DIRL = %11111101                              ' setup pins for LCD
  HIGH Reset                                    ' alert the DS1620
  SHIFTOUT DQ, Clock, LSBFIRST, [WrCfg, %10]    ' use with CPU; free-run
  LOW Reset
  PAUSE 10
  HIGH Reset
  SHIFTOUT DQ, Clock, LSBFIRST, [StartC]        ' start conversions
  LOW Reset

LCD_Init: 
  PAUSE 500                                     ' let the LCD settle
  LCDbus = %0011                                ' 8-bit mode 
  PULSOUT E, 1
  PAUSE 5
  PULSOUT E, 1
  PULSOUT E, 1
  LCDbus = %0010                                ' 4-bit mode
  PULSOUT E, 1
  char = %00001100                              ' disp on, crsr off, blink off
  GOSUB LCD_Command
  char = %00000110                              ' inc crsr, no disp shift
  GOSUB LCD_Command


' ------------------------------------------------------------------------------
' Program Code
' ------------------------------------------------------------------------------

Main:
  GOSUB Get_Temperature                         ' read the DS1620

  char = ClrLCD                                 ' clear the LCD
  GOSUB LCD_Command
  PAUSE 500
  index = tempC                               ' get EE address of message

Read_Char:
  READ index, char                              ' get character from EEPROM
  IF (char = 0) THEN Msg_Done                   ' if 0, message is complete
  GOSUB LCD_Write                               ' write the character
  index = index + 1                             ' point to next character
  GOTO Read_Char                                ' go get it

Msg_Done:                                       ' the message is complete
  PAUSE 10                                    ' wait 2 seconds
  char = CrsrHm                                 ' move the cursor home
  GOSUB LCD_Command
  char = %00001110                              ' turn the cursor on
  GOSUB LCD_Command
  PAUSE 10

  char = CrsrRt
  FOR index = 1 TO 15                           ' move the cursor accross display
    GOSUB LCD_Command
    PAUSE 10
  NEXT

  FOR index = 14 TO 0                           ' go backward by moving cursor
    char = DDRam + index                        '  to a specific address
    GOSUB LCD_Command
    PAUSE 10
  NEXT

  char = %00001101                              ' cursor off, blink on
  GOSUB LCD_Command
  PAUSE 10
        
  char = %00001100                              ' blink off
  GOSUB LCD_Command

  FOR index = 1 TO 10                           ' flash display
    char = char ^ %00000100                     ' toggle display bit
    GOSUB LCD_Command
    PAUSE 10       
  NEXT
  PAUSE 10

  FOR index = 1 TO 16                           ' shift display
    char = DispRt
    GOSUB LCD_Command
    PAUSE 10
  NEXT
  PAUSE 10

  FOR index = 1 TO 16                           ' shift display back
    char = DispLf
    GOSUB LCD_Command
    PAUSE 10
  NEXT
  PAUSE 10
  GOTO Main                                     ' do it all over

  END


' ------------------------------------------------------------------------------
' Subroutines
' ------------------------------------------------------------------------------

LCD_Command: 
  LOW RS                                        ' enter command mode

LCD_Write:
  LCDbus = char.HIGHNIB                         ' output high nibble
  PULSOUT E, 1                                  ' strobe the Enable line
  LCDbus = char.LOWNIB                          ' output low nibble
  PULSOUT E, 1
  HIGH RS                                       ' return to character mode
  RETURN

Get_Temperature:
  HIGH Reset                                    ' alert the DS1620
  SHIFTOUT DQ, Clock, LSBFIRST, [RdTmp]         ' give command to read temp
  SHIFTIN DQ, Clock, LSBPRE, [tempIn\9]         ' read it in
  LOW Reset                                     ' release the DS1620

  tSign = sign                                  ' save sign bit
  tempIn = tempIn / 2                           ' round to whole degrees
  IF (tSign = 0) THEN No_Neg1
  tempIn = tempIn | $FF00                       ' extend sign bits for negative

No_Neg1:
  tempC = tempIn                                ' save Celsius value
  tempIn = tempIn */ $01CC                      ' multiply by 1.8
  IF (tSign = 0) THEN No_Neg2                   ' if negative, extend sign bits
  tempIn = tempIn | $FF00

No_Neg2:
  tempIn = tempIn + 32                          ' finish C -> F conversion
  tempF = tempIn                                ' save Fahrenheit value
  RETURN