owarray.pbas

ibutton from dallas implementation with microcontroller

'This demo is to show how to read 8 bytes of data via 1-wire protocol.
'The core of the example is the function [b]Ow_Read_Serial[/b].
'The example can be further opimized.
'
'
'******************************************************************************
' microcontroller : P16F877A
'
' Project: Dallas iButton
'
' The project was written for P16F877A, but with minor adjustments can be used
' with any other PIC MCU.
'
' The example demonstrates 1-wire communication with electronic key

' DS1990A connected to RD2 pin. Upon reset, PIC reads all 64 bits (8 bytes)
' of iButton key and prints them on LCD in hex. LCD is 4-wire on PORTB
'******************************************************************************

program OwArray

dim text1 as char[17]  ' message1 on LCD
dim text2 as char[17]  ' message2 on LCD
dim Js as byte[8]      ' accepts code from iButton
dim presence_check as byte
const pin_ow = 2       ' pin used for 1Wire

' -------------------------------------------------------------
' Procedure for converting byte variable to HEX and displaying
' it on LCD display.
'
' procedure int2hex(row, start_x : byte  number : byte)
' row     - LCD line,
' start_x - position of first hex digit (left to right)
' -------------------------------------------------------------

sub procedure int2hex(dim row as byte, dim start_x as byte, dim number as byte)
dim high as byte
dim low as byte
    ' high nibble
    high = ((number and $F0) >> 4)+ 48    ' + "0"
    if (high > 57) then  high = high + 7  ' > "9"
    end if

    ' low nibble
    low = (number and $0F) + 48           ' + "0" low nibble
    if (low > 57) then low = low + 7      ' > "9"
    end if

    Lcd_Chr(row, start_x, high)
    Lcd_Chr(row, start_x + 1, low)
end sub

'Ow_Read_Serial reads 8 bytes via 1-wire protocol and
'places them into the array "out". The destination array
'needs to be at least 8 bytes in size
sub procedure Ow_Read_Serial(dim byref PORT as byte, dim pin as byte, dim byref out as byte[8])
dim i as byte
dim tmpRead as byte
   i = 0
   while i <= 7                      ' we will move 8 bytes
     tmpRead = ow_read(PORT,PIN)     ' get one byte from Dallas iButton
     out[i] = tmpRead
     inc(i)                          ' next i
   wend
end sub

main:

   PORTB  =   0                     ' initialize portb on 0
   trisb  =   0                     ' portb is output
   text1  = "mikro iButton:"
   text2  = "not present     "

   Lcd_Init(PORTB)

   Lcd_Cmd(LCD_CURSOR_OFF)
   LCD_Out(1, 1, text1)      ' print initial message

   _loop:
       ' first, we read iButton if present on pin RD2
       ' if not present, print appropriate message on LCD
       trisd = 255
       ow_reset(PORTD,pin_ow)            ' onewire reset signal
       ow_write(PORTD,pin_ow,$33)        ' read iButton
       delay_us(120)                ' pause

       Ow_Read_Serial(PORTD, pin_ow, Js) ' read 8 bytes of Dallas iButton


       ' if iButton is not present, j1 ~ j8 will be at 255, so we can easily
       ' test them:
       presence_check = js[0] and js[1] and js[2] and js[3] and js[4] and js[5] and js[6] and js[7]

       if presence_check = $FF then   ' iButton is not present
         LCD_Out(2, 1, text2)  ' print message
       else                           ' iButton is present, convert codes to hex and print them on LCD
          int2hex(2, 1,  js[7])
          int2hex(2, 3,  js[6])
          int2hex(2, 5,  js[5])
          int2hex(2, 7,  js[4])
          int2hex(2, 9,  js[3])
          int2hex(2, 11, js[2])
          int2hex(2, 13, js[1])
          int2hex(2, 15, js[0])
       end if

       Delay_ms(500)
   goto _loop
end.