'
'  Program: RF Receiver module
'  Author:  (c) 2008 by A Fox Consulting & Design
'           http://www.afox-consulting.com
'  Date:    01/23/2008
'
' {$STAMP BS2}
' {$PBASIC 2.5}

_RFIn  PIN 0
_LED   PIN 1
_LED2  PIN 2
_LED3  PIN 3

BAUD    CON 16780  ' N2400
junk    CON $55    ' Wake-up
sync    CON $83

' This is our 16-byte data packet we will use for our RF
' communications. Format:
' b00 b01 b02 b03 b04 b05 b06 b07 b08 b09 b10 b11 b12 b13 b14 b15
' $83 ...................data................................ CRC
DataPacket VAR Byte
DataBlock  VAR Byte(14)
crc_in     VAR Byte

i          VAR Nib
j          VAR Nib
k          VAR Byte
b          VAR Byte
crc        VAR Byte

DIRA = %0110

Main:
  SERIN _RFIn, BAUD, [WAIT(sync), STR DataBlock\14, crc_in]
  DataPacket = sync
'  DEBUG "Data Packet: "
'  FOR i = 0 TO 15
'    DEBUG DEC DataPacket(i)," "
'  NEXT
'  DEBUG CR
  IF DataBlock(0) = "F" THEN
    ' Check CRC
    GOSUB CalcCRC
    IF crc = crc_in THEN
      PULSOUT _LED, 25000    ' Flash blue LED for 50ms.
    ELSE
      PULSOUT _LED2, 25000   ' Flash yellow LED for 50ms.
    ENDIF
  ELSE
    PULSOUT _LED3, 25000     ' Flash red LED for 50ms.
  ENDIF
  GOTO Main

CalcCRC:
  crc = 0
  FOR i = 0 TO 13
    b = DataBlock(i)
    FOR j = 0 TO 7
      k = b ^ CRC & %0001
      IF k > 0 THEN k = $8C
      crc = crc >> 1 ^ k
      b = b >> 1
    NEXT
  NEXT
RETURN