' Name        : HSERX20.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : PM or MPASM
' Target PIC  : PIC16F690 or similar type compatible with LAB-X20 board
' Hardware    : LAB-X20 Experimenter Board
' Oscillator  : 4MHz external crystal
' Keywords    : HSERIN, HSEROUT
' Description : PICBASIC PRO program to send and receive from the hardware
' serial port. LEDs count characters and flash error if none received for
' 10 seconds.
'

char Var Byte   ' Storage for serial character
cnt  Var Byte   ' Storage for character counter

   ANSEL = %00000000    ' Set all pins digital
   ANSELH = %00000000
   TRISA = %11001111    ' Set PORTA.4,5 to outputs
   PORTA = 0            ' Turn off LEDs
   cnt = 0              ' Zero character counter

mainloop:
   Hserin 10000, allon, [char]  ' Get a char from serial port
   Hserout [char]       ' Send char out serial port

   cnt = cnt + 1        ' Increment character count
   PORTA = cnt << 4     ' Send count to LED
   Goto mainloop        ' Do it all over again

allon:
   PORTA = %00110000    ' Error - no character received
   Pause 500            ' Blink all LEDs
   PORTA = 0
   Pause 500
   Goto allon

   End