;;
  ;;  mur.sat
  ;;
  ;;  Somewhen in the year 2011, mur.at will have a nano satellite launched
  ;;  into a low earth orbit (310 km above the surface of our planet). The
  ;;  satellite itself is a TubeSat personal satellite kit, developed and
  ;;  launched by interorbital systems. mur.sat is a joint venture of mur.at,
  ;;  ESC im Labor and realraum.
  ;;
  ;;  Please visit the project hompage at sat.mur.at for further information.
  ;; 
  ;;
  ;;  Copyright (C) 2011 Christian Pointner <equinox@mur.at>
  ;;                         
  ;;  This file is part of mur.sat.
  ;;
  ;;  mur.sat is free software: you can redistribute it and/or modify
  ;;  it under the terms of the GNU General Public License as published by
  ;;  the Free Software Foundation, either version 3 of the License, or
  ;;  any later version.
  ;;
  ;;  mur.sat is distributed in the hope that it will be useful,
  ;;  but WITHOUT ANY WARRANTY; without even the implied warranty of
  ;;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  ;;  GNU General Public License for more details.
  ;;
  ;;  You should have received a copy of the GNU General Public License
  ;;  along with mur.sat. If not, see <http://www.gnu.org/licenses/>.
  ;;
  ;; -------------------------------------
  ;; PREAMBLE

  LIST      p=16F887
  include   "p16f887.inc"
  __config  _CONFIG1,  _DEBUG_OFF & _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_NSLEEP & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_CLKOUT
  __config  _CONFIG2,  _BOR21V & _WRT_OFF
  
  ;; -------------------------------------
  ;; DEFINES
  ;;   constants

  ;; I/O Pins

  ;; variables
  ;;     page 0 only
TMP           EQU H'0020'
WAIT_CNT      EQU H'0021'
  
  
  ;;     all pages
FSR_TEMP      EQU H'007D'  
W_TEMP        EQU H'007E'
STATUS_TEMP   EQU H'007F'

  ;;    bits 
  
  ;; -------------------------------------
  ;; Reset Vector
  org	      0
  goto      init

  ;; -------------------------------------
  ;; Interrupt Vector
  org	      4
  ;; save context
  movwf     W_TEMP
  swapf     STATUS,W
  movwf     STATUS_TEMP
  movf      FSR,w
  movwf     FSR_TEMP
  
  bcf       STATUS,RP0
  bcf       STATUS,RP1

  ;;  dispatch interrupt sources
  btfsc     PIR1,RCIF
  goto      int_uart_rx
  goto      interrupt_end
  
int_uart_rx
  call      uart_rx_byte
  btfsc     PIR1,RCIF
  call      uart_rx_byte
  btfss     RCSTA,OERR
  goto      int_uart_rx_oe
  goto      interrupt_end
  
int_uart_rx_oe
  bcf       RCSTA,CREN
  bsf       RCSTA,CREN

  goto      interrupt_end


interrupt_end
  ;; restore context
  movf      FSR_TEMP,w
  movwf     FSR
  swapf     STATUS_TEMP,W
  movwf     STATUS
  swapf     W_TEMP,F
  swapf     W_TEMP,W
  retfie

  ;; -------------------------------------
  ;; INIT
init
  ;; bank 3
  bsf       STATUS,RP0
  bsf       STATUS,RP1
  movlw     b'00000000'
  movwf     BAUDCTL
  
  ;; bank 1
  bsf       STATUS,RP0
  bcf       STATUS,RP1
  movlw     b'10000000'
  movwf     OPTION_REG
  clrf      PSTRCON
  movlw     b'01101000'
  movwf     OSCCON
  movlw     b'11111111'
  movwf     TRISA
  movlw     b'11111111'
  movwf     TRISB
  movlw     b'11111111'
  movwf     TRISC
  movlw     b'11111111'
  movwf     TRISD
  movlw     b'00100100'
  movwf     TXSTA
  movlw     .12
  movwf     SPBRG
  clrf      SPBRGH
  movlw     b'00100000'
  movwf     PIE1
  clrf      PIE2
  
  ;; bank 0
  bcf       STATUS,RP0 
  bcf       STATUS,RP1
  movlw     b'10010000'
  movwf     RCSTA
  movlw     B'01000000'
  movwf     INTCON
  
  clrf      TMP
  bsf       INTCON,GIE

  goto      main


  ;; -------------------------------------
  ;; SUBROUTINES
wait_ms
  movwf     WAIT_CNT
wait_next
  movlw     .9
  movwf     TMR0
  bcf       INTCON,T0IF
wait_loop
  btfss     INTCON,T0IF
  goto      wait_loop
  decfsz    WAIT_CNT,f
  goto      wait_next
  return

  ;; -------------------------------------
uart_rx_byte
  btfsc     RCSTA,FERR
  goto      uart_rx_fe
  movf      RCREG,w             ; TODO: move to input string
  movwf     TMP
  return

uart_rx_fe
  movf      RCREG,w
  return

  ;; -------------------------------------
  ;; MAINLOOP
main
  ;; movf      TMP,f
  ;; btfsc     STATUS,Z
  ;; goto      main

  movlw     '.' 
  movwf     TXREG
  movlw     .255
  call      wait_ms
  
  goto      main
  
powerdown
  sleep
  nop
  goto      main
  
  ;; -------------------------------------
  ;; END
  end