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  ;;
  ;;  mur.sat
  ;;
  ;;  Somewhen in the year 2012, 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=12F635
  include   "p12f635.inc"
  __config _WUREN_OFF & _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT
  
  ;; -------------------------------------
  ;; DEFINES
  ;;   constants

DOT_DEF     EQU .256 - .21      ; .29
DASH_DEF    EQU .256 - .63      ; .87
WSPACE_DEF  EQU .256 - .147     ; .203
TUNE_DEF    EQU DOT_DEF
BCNINTL_DEF EQU .256 - .200
BCNINTH_DEF EQU .255
START_CHAR  EQU 'N'
ACK_CHAR    EQU 'A'
OSC_LOW     EQU b'00000000'
OSC_HIGH    EQU b'01100000'
    
  ;;   I/O Pins
CWENABLE    EQU GP0
CWOUT       EQU GP1
SCLK        EQU GP2
SDAT        EQU GP4
CLK_1HZ     EQU GP5
  
  ;;   variables
  ;;     page 0 only
ELEMENT     EQU H'0040'
ELECNT      EQU H'0041'
CHAR        EQU H'0042'
PARITY      EQU H'0043'
CHARCNT     EQU H'0044'
PENTLE0     EQU H'0045'
PENTLE1     EQU H'0046'
PENTLECNT   EQU H'0047'
ACK_DATA    EQU H'0048'
TMP1        EQU H'0049'
TMP2        EQU H'004A'

RX_FSR_TMP  EQU H'004B'
RX_CSUM     EQU H'004C'
RX_BIT_CNT  EQU H'004D'
RX_BYTE_CNT EQU H'004E'
RX_DLEN     EQU H'004F'
RX_CMD      EQU H'0050'
RX_D_START  EQU H'0051'
RX_D_END    EQU H'005F'
  
  ;;     all pages
BEACON_INTL EQU H'0070'
BEACON_INTH EQU H'0071'
DOT         EQU H'0072'
ESPACE      EQU DOT
DASH        EQU H'0073'
CSPACE      EQU DASH
WSPACE      EQU H'0074'
TUNE        EQU H'0075'

NVSTATE     EQU H'007A'
BEACONCNTH  EQU H'007B'
BEACONCNTL  EQU H'007C'
STATE       EQU H'007D'
W_TEMP      EQU H'007E'
STATUS_TEMP EQU H'007F'

  ;;    bits STATE
startbeacon EQU .0
rxcomplete  EQU .1

  ;;    bits NVSTATE
safe        EQU .0

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

  ;; -------------------------------------
  ;; Interrupt Vector
  org	      .4
  ;; save context
  movwf     W_TEMP
  swapf     STATUS,W
  movwf     STATUS_TEMP

  btfss     INTCON,INTF
  goto      beacon_int_int
ext_int
  bcf       INTCON,INTF
  btfsc     STATE,rxcomplete
  goto      interrupt_end
  bsf       STATUS,RP0
  movlw     OSC_HIGH
  movwf     OSCCON
  ;;  we are on high OSC now
  bcf       STATUS,RP0
  bsf       WDTCON,SWDTEN
  clrf      RX_CSUM
  movf      FSR,w
  movwf     RX_FSR_TMP
  movlw     RX_CMD
  movwf     FSR
  bcf       STATUS,IRP
  call      rx_byte
  movlw     b'00001111'
  andwf     RX_CMD,w
  movwf     RX_BYTE_CNT
  movwf     RX_DLEN
  btfsc     STATUS,Z
  goto      ext_int_send_csum

ext_int_next
  incf      FSR,f
  call      rx_byte
  decfsz    RX_BYTE_CNT,f
  goto      ext_int_next
  
ext_int_send_csum
;;   call      rx_send_csum
;;   movf      RX_FSR_TMP,w
;;   movwf     FSR
  swapf     RX_CMD,w
  andlw     b'00001111'
  movwf     RX_CMD
;; ext_int_wait_ack_low
;;   btfsc     GPIO,SCLK
;;   goto      ext_int_wait_ack_low
;; ext_int_wait_ack_high
;;   btfss     GPIO,SCLK
;;   goto      ext_int_wait_ack_high
;;   btfss     GPIO,SDAT
  bsf       STATE,rxcomplete
  bcf       WDTCON,SWDTEN
  bsf       STATUS,RP0
  movlw     OSC_LOW
  movwf     OSCCON
  ;;  back on low OSC
  goto      interrupt_end

  
beacon_int_int
  bcf       STATUS,RP0
  bcf       T1CON,TMR1ON
  movf      BEACON_INTL,w
  movwf     TMR1L
  movf      BEACON_INTH,w
  movwf     TMR1H
  bsf       T1CON,TMR1ON
  bcf       PIR1,TMR1IF
  bsf       STATE,startbeacon
  goto      interrupt_end

interrupt_end
  ;; restore context
  swapf     STATUS_TEMP,W
  movwf     STATUS
  swapf     W_TEMP,F
  swapf     W_TEMP,W
  retfie

  ;; -------------------------------------
  ;; TABLES

  ;; Morse Codes: 0=dot, 1=dash
getcw
  addwf     PCL,f
  nop
  retlw     b'00010000'                 ; !
  retlw     b'01001000'                 ; "
  retlw     b'00000000'                 ; #
  retlw     b'00010010'                 ; $
  retlw     b'00000000'                 ; %
  retlw     b'01000000'                 ; &
  retlw     b'01111000'                 ; '
  retlw     b'10110000'                 ; (
  retlw     b'10110100'                 ; )
  retlw     b'00000000'                 ; *
  retlw     b'01010000'                 ; +
  retlw     b'11001100'                 ; ,
  retlw     b'10000100'                 ; -
  retlw     b'01010100'                 ; .
  retlw     b'10010000'                 ; /
  retlw     b'11111000'                 ; 0
  retlw     b'01111000'                 ; 1
  retlw     b'00111000'                 ; 2  
  retlw     b'00011000'                 ; 3
  retlw     b'00001000'                 ; 4
  retlw     b'00000000'                 ; 5  
  retlw     b'10000000'                 ; 6
  retlw     b'11000000'                 ; 7
  retlw     b'11100000'                 ; 8  
  retlw     b'11110000'                 ; 9
  retlw     b'11100000'                 ; :
  retlw     b'10101000'                 ; ;
  retlw     b'00010100'                 ; <
  retlw     b'10001000'                 ; =
  retlw     b'10001010'                 ; >
  retlw     b'00110000'                 ; ?  
  retlw     b'01000000'                 ; @ 
  retlw     b'01000000'                 ; A
  retlw     b'10000000'                 ; B
  retlw     b'10100000'                 ; C
  retlw     b'10000000'                 ; D
  retlw     b'00000000'                 ; E
  retlw     b'00100000'                 ; F
  retlw     b'11000000'                 ; G
  retlw     b'00000000'                 ; H
  retlw     b'00000000'                 ; I
  retlw     b'01110000'                 ; J
  retlw     b'10100000'                 ; K
  retlw     b'01000000'                 ; L
  retlw     b'11000000'                 ; M
  retlw     b'10000000'                 ; N
  retlw     b'11100000'                 ; O
  retlw     b'01100000'                 ; P
  retlw     b'11010000'                 ; Q
  retlw     b'01000000'                 ; R
  retlw     b'00000000'                 ; S
  retlw     b'10000000'                 ; T
  retlw     b'00100000'                 ; U
  retlw     b'00010000'                 ; V
  retlw     b'01100000'                 ; W
  retlw     b'10010000'                 ; X
  retlw     b'10110000'                 ; Y
  retlw     b'11000000'                 ; Z
  
  ;; Morse Code Length
getcwlen
  addwf     PCL,f
  nop       
  retlw     .5                          ; !
  retlw     .6                          ; "
  retlw     .0                          ; #
  retlw     .7                          ; $
  retlw     .0                          ; %
  retlw     .5                          ; &
  retlw     .6                          ; '
  retlw     .5                          ; (
  retlw     .6                          ; )
  retlw     .0                          ; *
  retlw     .5                          ; +
  retlw     .6                          ; ,
  retlw     .6                          ; -
  retlw     .6                          ; .
  retlw     .5                          ; /
  retlw     .5                          ; 0
  retlw     .5                          ; 1
  retlw     .5                          ; 2  
  retlw     .5                          ; 3
  retlw     .5                          ; 4
  retlw     .5                          ; 5  
  retlw     .5                          ; 6
  retlw     .5                          ; 7
  retlw     .5                          ; 8  
  retlw     .5                          ; 9
  retlw     .6                          ; :
  retlw     .6                          ; ;
  retlw     .6                          ; <
  retlw     .5                          ; =
  retlw     .7                          ; >
  retlw     .6                          ; ?  
  retlw     .6                          ; @ 
  retlw     .2                          ; A
  retlw     .4                          ; B
  retlw     .4                          ; C
  retlw     .3                          ; D
  retlw     .1                          ; E
  retlw     .4                          ; F
  retlw     .3                          ; G
  retlw     .4                          ; H
  retlw     .2                          ; I
  retlw     .4                          ; J
  retlw     .3                          ; K
  retlw     .4                          ; L
  retlw     .2                          ; M
  retlw     .2                          ; N
  retlw     .3                          ; O
  retlw     .4                          ; P
  retlw     .4                          ; Q
  retlw     .3                          ; R
  retlw     .3                          ; S
  retlw     .1                          ; T
  retlw     .3                          ; U
  retlw     .4                          ; V
  retlw     .3                          ; W
  retlw     .4                          ; X
  retlw     .4                          ; Y
  retlw     .4                          ; Z

  ;; Base32 Code
base32
  addwf     PCL,f
  retlw     'A'
  retlw     'B'
  retlw     'C'
  retlw     'D'
  retlw     'E'
  retlw     'F'
  retlw     'G'
  retlw     'H'
  retlw     'I'
  retlw     'J'
  retlw     'K'
  retlw     'L'
  retlw     'M'
  retlw     'N'
  retlw     'O'
  retlw     'P'
  retlw     'Q'
  retlw     'R'
  retlw     'S'
  retlw     'T'
  retlw     'U'
  retlw     'V'
  retlw     'W'
  retlw     'X'
  retlw     'Y'
  retlw     'Z'
  retlw     '2'
  retlw     '3'
  retlw     '4'
  retlw     '5'
  retlw     '6'
  retlw     '7'

  ;; fixed strings
callsign
  addwf     PCL,f
  nop
  retlw     'R'
  retlw     'U'
  retlw     'M'
  retlw     '6'
  retlw     'E'
  retlw     'O'

  ;; -------------------------------------
  ;; INIT
init
  ;; bank 1
  bcf       STATUS,IRP
  bsf       STATUS,RP0
  bcf       STATUS,RP1

  movlw     b'01000011'
  movwf     OPTION_REG
  movlw     b'11111100'
  movwf     TRISIO
  movlw     OSC_LOW
  movwf     OSCCON
  movlw     b'00000001'
  movwf     PIE1
  
  bcf       STATUS,RP0  

  ;; bank 0
  movlw     b'00010010'
  movwf     WDTCON
  movlw     b'01010000'
  movwf     INTCON
  
  movlw     b'00000111'
  movwf     CMCON0
  movlw     b'00000010'
  movwf     CMCON1
  movlw     b'00000110'
  movwf     T1CON
  
  bcf       GPIO,CWOUT
  bcf       GPIO,CWENABLE

  clrf      RX_DLEN
  bcf       STATE,rxcomplete
  clrf      NVSTATE             ; TODO: read State from EEPROM
  ;; movlw     .42                 
  movlw     .0
  movwf     BEACONCNTL          ; TODO: read Beaconcnt from EEPROM
  ;; movlw     .23
  movlw     .0
  movwf     BEACONCNTH
  movlw     BCNINTL_DEF         ; TODO: read Beacon Interval from EEPROM
  movwf     BEACON_INTL
  movlw     BCNINTH_DEF
  movwf     BEACON_INTH

  movlw     DOT_DEF             ; TODO: read cw timings from EEPROM
  movwf     DOT                 ;   - DOT: length of .
  movlw     DASH_DEF            ;   - DASH: length of -
  movwf     DASH                ;   - WSPACE: length word space
  movlw     WSPACE_DEF          ;   - TUNE: tune in time of oscillator
  movwf     WSPACE
  movlw     TUNE_DEF
  movwf     TUNE

  movf      BEACON_INTL,w
  movwf     TMR1L
  movf      BEACON_INTH,w
  movwf     TMR1H
  bcf       STATE,startbeacon
  bsf       T1CON,TMR1ON
  
  bsf       INTCON,GIE
  goto      main

  ;; -------------------------------------
  ;; SUBROUTINES
rx_byte
  movlw     .8
  movwf     RX_BIT_CNT
  clrf      INDF  
rx_byte_clk_low
  btfsc     GPIO,SCLK
  goto      rx_byte_clk_low
rx_byte_clk_high
  btfss     GPIO,SCLK
  goto      rx_byte_clk_high
  btfsc     GPIO,SDAT
  bsf       INDF,0
  decfsz    RX_BIT_CNT,f
  goto      rx_byte_next

  movf      INDF,w
  xorwf     RX_CSUM,f
  return

rx_byte_next
  rlf       INDF,f
  goto      rx_byte_clk_low

  ;; -------------------------------------
rx_send_csum
  bsf       STATUS,RP0
  bcf       TRISIO,SDAT
  bcf       STATUS,RP0  
  movlw     .8
  movwf     RX_BIT_CNT
rx_send_clk_low
  btfsc     GPIO,SCLK
  goto      rx_send_clk_low
rx_send_clk_high
  btfss     GPIO,SCLK
  goto      rx_send_clk_high
  btfss     RX_CSUM,7
  bcf       GPIO,SDAT
  btfsc     RX_CSUM,7
  bsf       GPIO,SDAT
  decfsz    RX_BIT_CNT,f
  goto      rx_send_next

  bsf       STATUS,RP0
  bsf       TRISIO,SDAT
  bcf       STATUS,RP0
  return

rx_send_next
  rlf       RX_CSUM,f
  goto      rx_send_clk_low

  ;; -------------------------------------
dottime
  movwf     TMR0
  bcf       INTCON,T0IF
dot_inner
  btfss     INTCON,T0IF
  goto      dot_inner
  return

  ;; -------------------------------------
send_char
  movwf     CHAR
  movlw     'Z' + 1
  subwf     CHAR,w
  btfsc     STATUS,C
  return
  movlw     ' '
  subwf     CHAR,f
  btfss     STATUS,C
  return
  btfsc     STATUS,Z
  return

  movf      CHAR,w
  call      getcw
  movwf     ELEMENT
  movf      CHAR,w
  call      getcwlen
  movwf     ELECNT
  movf      ELECNT,f
  btfsc     STATUS,Z
  return
  movf      CHAR,w
  xorwf     PARITY,f
  
char_next_element
  bsf       GPIO,CWOUT
  btfss     ELEMENT,7
  movf      DOT,w
  btfsc     ELEMENT,7
  movf      DASH,w
  call      dottime
  bcf       GPIO,CWOUT

  rlf       ELEMENT,f

  decfsz    ELECNT,f
  goto      char_espace
  return

char_espace
  movf      ESPACE,w
  call      dottime
  goto      char_next_element
  
  ;; -------------------------------------
send_callsign
  movlw     .6
  movwf     CHARCNT

callsign_next_char
  call      callsign
  call      send_char
  decfsz    CHARCNT,f
  goto      callsign_cspace
  return

callsign_cspace
  movf      CSPACE,w
  call      dottime
  movf      CHARCNT,w
  goto      callsign_next_char
  
  ;; -------------------------------------
send_base32
  movwf     PENTLECNT

case0  
  rrf       INDF,w
  movwf     PENTLE0
  rrf       PENTLE0,f
  rrf       PENTLE0,w
  andlw     b'00011111'
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case1
  return

case1
  movf      CSPACE,w
  call      dottime
  rlf       INDF,w
  movwf     PENTLE0
  rlf       PENTLE0,w
  andlw     b'00011100'
  movwf     PENTLE0
  incf      FSR,f
  swapf     INDF,w
  movwf     PENTLE1
  rrf       PENTLE1,f
  rrf       PENTLE1,w
  andlw     b'00000011'
  iorwf     PENTLE0,w
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case2
  return

case2
  movf      CSPACE,w
  call      dottime
  rrf       INDF,w
  andlw     b'00011111'
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case3
  return

case3
  movf      CSPACE,w
  call      dottime
  swapf     INDF,w
  andlw     b'00010000'
  movwf     PENTLE0
  incf      FSR,f
  swapf     INDF,w
  andlw     b'00001111'
  iorwf     PENTLE0,w
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case4
  return

case4
  movf      CSPACE,w
  call      dottime
  rlf       INDF,w
  andlw     b'00011110'
  movwf     PENTLE0
  incf      FSR,f
  btfsc     INDF,7
  bsf       PENTLE0,0
  movf      PENTLE0,w
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case5
  return

case5
  movf      CSPACE,w
  call      dottime
  rrf       INDF,w
  movwf     PENTLE0
  rrf       PENTLE0,w
  andlw     b'00011111'
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case6
  return

case6
  movf      CSPACE,w
  call      dottime
  swapf     INDF,w
  movwf     PENTLE0
  rrf       PENTLE0,w
  andlw     b'00011000'
  movwf     PENTLE0
  incf      FSR,f
  swapf     INDF,w
  movwf     PENTLE1
  rrf       PENTLE1,w
  andlw     b'00000111'
  iorwf     PENTLE0,w
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      case7
  return

case7
  movf      CSPACE,w
  call      dottime
  movf      INDF,w
  andlw     b'00011111'
  call      base32
  call      send_char
  decfsz    PENTLECNT,f
  goto      caseend
  return

caseend
  movf      CSPACE,w
  call      dottime
  incf      FSR,f
  goto      case0
  
  ;; -------------------------------------
send_cnt
  rlf       BEACONCNTL,w
  movwf     TMP2
  rlf       BEACONCNTH,w
  movwf     TMP1
  movlw     TMP1
  movwf     FSR
  bcf       STATUS,IRP
  movlw     .3
  call      send_base32
  return

  ;; -------------------------------------
send_parity
  movf      PARITY,w
  btfsc     PARITY,5
  xorlw     b'00000001'
  andlw     b'00011111'
  call      base32
  call      send_char

  movf      WSPACE,w
  call      dottime
  return

  ;; -------------------------------------
send_beacon
  bsf       GPIO,CWENABLE
  movf      TUNE,w
  call      dottime
  clrf      PARITY

  movlw     START_CHAR
  call      send_char

  movf      WSPACE,w
  call      dottime
    
  call      send_callsign

  movf      WSPACE,w
  call      dottime

  call      send_cnt

  movf      WSPACE,w
  call      dottime

  call      send_parity

  incfsz    BEACONCNTL,f
  goto      beacon_end
  incf      BEACONCNTH,f
  ;; TODO write new cnt value to EEPROM
  
beacon_end
  bcf       GPIO,CWENABLE
  return

  ;; -------------------------------------
send_ack
  movwf     ACK_DATA
  bsf       GPIO,CWENABLE
  movf      TUNE,w
  call      dottime
  clrf      PARITY

  movlw     ACK_CHAR
  call      send_char

  movf      WSPACE,w
  call      dottime

  movf      RX_CMD,w
  addlw     'A'
  call      send_char

  movf      WSPACE,w
  call      dottime

  movlw     RX_CMD
  movwf     FSR
  bcf       STATUS,IRP
  movf      RX_DLEN,w
  andlw     b'00001111'
  movwf     TMP1
  btfsc     STATUS,Z
  goto      ack_parity
ack_next
  incf      FSR,f
  movf      INDF,w
  call      send_char
  movf      CSPACE,w
  call      dottime
  decfsz    TMP1,f
  goto      ack_next

  ;; movf      ACK_DATA,w
  ;; call      send_char
  movf      CSPACE,w
  call      dottime

ack_parity
  call      send_parity

  bcf       GPIO,CWENABLE
  return

  ;; -------------------------------------
  ;; MAINLOOP
main
  ;; this gets called after reset and whenever a wakeup occured
  ;; (after timer1 overflow or interrupt on GP2)
  btfsc     STATE,startbeacon
  goto      beaconint_elapsed
  btfsc     STATE,rxcomplete
  goto      msg_received
  goto      powerdown

  ;; this gets called every beacon interval
beaconint_elapsed
  bcf       STATE,startbeacon
  btfss     NVSTATE,safe
  call      send_beacon
  goto      powerdown

  ;; this gets called whenever a message was received from ihu
msg_received
  call      send_ack
  bcf       STATE,rxcomplete
  clrf      RX_DLEN
  
powerdown
  sleep
  nop
  goto      main
  
  ;; -------------------------------------
  ;; END
  end