'--------------------------------------------------------------------------------
'name                     : I2C_LCD_tst.bas
'purpose                  : Character LCD (Strawberry LINUX), I2C I/F
'micro controller         : Mega1284
'--------------------------------------------------------------------------------


'--------------------------------------------------------------------------------
Rem Used ports
'
' LCD I/F (TWI = hardware I2C)
' Hardware I2C pins on Mega1284 are
'
' PC0 : SCL
' PC1 : SDA
'--------------------------------------------------------------------------------


$regfile = "m1284pdef.dat"
$crystal = 8192000
' 8.192MHz Xtal clock

$hwstack = 64
$swstack = 64
$framesize = 40

Const Contrast = &B0010_0000
' LCD contrast (from &B0000_0000 to &B0011_1111)

Const I2caddr = &B0111_1100
' I2C slave address (= &B0011_1110) x 2
' (address x 2) is needed for I2C protocol.


$lib "i2c_twi.lbx"
' Include BASCOM I2C library (for hardware I2C = TWI)

Rem  I2C I/O pin definition
' Since this program uses hardware I2C, i.e. TWI,
' hardware I2C pins on Mega1284 are defined.

Config Scl = Portc.0
' SCL
Config Sda = Portc.1
' SDA


Rem type definition of variables

' for working

Dim I As Integer
Dim B As Byte
Dim S As String * 32

Dim Saddr As Word
Dim Ns As Integer
Dim Is0 As Integer
Dim Bs0 As Byte

Dim Twid1 As Byte , Twid2 As Byte


Rem program start

' I2C BUS initialize

Config Twi = 100000
' 100kHz Clock rate of hardware I2C = TWI
I2cinit

Waitms 40
' wait LCD ready from its power ON

' LCD initialize

Gosub Init_twi_lcd
' LCD initialize
Gosub Twi_cls
' Clear LCD Screen

S = "M1284 TWI LCD"
Gosub Print_twi
' print String S to LCD

Gosub Nextline
' goto lowerline

S = "Starting"
Gosub Print_twi
' print String S to LCD

Wait 3

Gosub Twi_cls
' Clear LCD Screen

S = "Number display"
Gosub Print_twi

For I = 1 To 10

    S = Str(i)
    S = S + "    "

    Gosub Nextline
    ' locate cursor to &H40 address

    Gosub Print_twi

    Wait 1

Next I

Gosub Topline

S = "Test END      "
Gosub Print_twi

End



Rem subroutines

' Data out to I2C bus
' Send 2 bytes (control byte (Twid1) and data (Twid2) byte)

I2cout:
   I2cstart
   I2cwbyte I2caddr
   ' send I2C address
   I2cwbyte Twid1
   ' send control byte (<B6> = RS bit)
   I2cwbyte Twid2
   ' send Instruction or Data
   ' (If RS bit in the preceding control byte = 1, then this byte = Data.
   '  If RS bit = 0, then this byte is interpretted as Instruction.)
   I2cstop
Return


' Initialize LCD

Init_twi_lcd:

   Twid1 = &B0000_0000
   ' set RS bit = 0 in control byte (RS=0 indicates Instruction transfer)

   Twid2 = &B0011_1000
   ' function set, 8-bit I/F, 2-line display
   Gosub I2cout
   Waitus 30

   Twid2 = &B0011_1001
   ' Extended mode function set, 8-bit I/F, 2-line display, instruction table 1
   Gosub I2cout
   Waitus 30

   Twid2 = &B0001_0100
   ' adjust internal OSC frequency, 1/5 bias
   Gosub I2cout
   Waitus 30

   B = Contrast And &H0F
   B = B Or &B0111_0000

   Twid2 = B
   ' set contrast lower 4-bit
   Gosub I2cout
   Waitus 30

   B = Contrast
   Shift B , Right , 4
   B = B And &H03
   B = B Or &B0101_1100

   Twid2 = B
   ' set contrast higher 2-bits, display ON, & power ON
   Gosub I2cout
   Waitus 30

   Twid2 = &B0110_1100
   ' follower control
   Gosub I2cout

   Waitms 300

   Twid2 = &B0011_1000
   ' function set, instruction table -> 0
   Gosub I2cout
   Waitus 30

   Twid2 = &B0000_1100
   ' display ON, cursor off
   Gosub I2cout
   Waitus 30

   Twid2 = &B0000_0110
   ' entry mode set: incremental addressing
   Gosub I2cout
   Waitus 30

Return


' Clear screen

Twi_cls:

   Twid1 = &B0000_0000
   ' set RS = 0 in control byte (RS=0 indicates Instruction transfer)

   Twid2 = &B0000_0001
   'clear display
   Gosub I2cout
   Waitms 2

   Twid2 = &B0000_0010
   ' reset cursor position
   Gosub I2cout
   Waitus 30

Return


' Print strings S to LCD

Print_twi:
   Saddr = Varptr(s)
   ' string variable S top address
   Ns = Len(s)
   ' string length

   For Is0 = 1 To Ns
      Bs0 = Inp(saddr)
      ' get a byte in the string
      Gosub Lcdchar
      ' print one char.
      Incr Saddr
   Next Is0

Return


' print a character Bs0 to LCD

Lcdchar:
   Twid1 = &B0100_0000
   ' set RS bit = 1 in control byte (RS=1 indicates Data transfer)
   Twid2 = Bs0

   Gosub I2cout
Return



' to lowerline

Nextline:
   Twid1 = &B0000_0000
   ' set RS = 0 in control byte (RS=0 indicates Instruction transfer)

   Twid2 = &HC0
   ' set DDRAM address to &H40
   Gosub I2cout

Return

' to upperline

Topline:
   Twid1 = &B0000_0000
   ' set RS = 0 in control byte (RS=0 indicates Instruction transfer)

   Twid2 = &H80
   ' set DDRAM address to &H00
   Gosub I2cout

Return