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|
;;
;; 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/>.
;;
;; -------------------------------------
ttx_send_byte
bsf STATUS,RP0
bcf TRISD,TTX_SDA
bcf STATUS,RP0
movwf TTX_BYTE
xorwf TTX_CSUM,f
movlw .8
movwf TTX_BIT_CNT
ttx_send_next_bit
btfsc TTX_BYTE,7
bsf PORTD,TTX_SDA
btfss TTX_BYTE,7
bcf PORTD,TTX_SDA
bsf PORTD,TTX_SCL
nop
nop
nop
bcf PORTD,TTX_SCL
nop
nop
nop
nop
rlf TTX_BYTE,f
decfsz TTX_BIT_CNT,f
goto ttx_send_next_bit
bsf STATUS,RP0
bsf TRISD,TTX_SDA
bcf STATUS,RP0
return
;; -------------------------------------
ttx_recv_byte
movlw .8
movwf TTX_BIT_CNT
ttx_recv_next_bit
bsf PORTD,TTX_SCL
nop
nop
nop
bcf PORTD,TTX_SCL
nop
nop
nop
nop
nop
rlf TTX_BYTE,f
btfsc PORTD,TTX_SDA
bsf TTX_BYTE,0
btfss PORTD,TTX_SDA
bcf TTX_BYTE,0
decfsz TTX_BIT_CNT,f
goto ttx_recv_next_bit
return
;; -------------------------------------
ttx_break
movlw .13
movwf TTX_BIT_CNT
ttx_wait_octet
decfsz TTX_BIT_CNT,f
goto ttx_wait_octet
return
;; -------------------------------------
ttx_send_frame
movwf TTX_BYTE
andlw b'00001111'
movwf TTX_BYTE_CNT
bsf PORTD,TTX_SCL
movlw .3
bcf PORTD,TTX_SCL
call wait_ms
clrf TTX_CSUM
movf TTX_BYTE,w
call ttx_send_byte
movf TTX_BYTE_CNT,f
btfsc STATUS,Z
return
ttx_next_byte
call ttx_break
movf INDF,w
call ttx_send_byte
incf FSR,f
decfsz TTX_BYTE_CNT,f
goto ttx_next_byte
call ttx_break
call ttx_recv_byte
movf TTX_BYTE,w
xorwf TTX_CSUM,w
btfss STATUS,Z
goto ttx_csum_error
return
ttx_csum_error
;; TODO: react to comm error
return
;; -------------------------------------
|
