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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/>.
;;
;; -------------------------------------
i2c_init
movlw I2C_MASK ; as every write access is read-update-write this needs
andwf I2C_PORT,f ; to be done in one step (external pull-ups!)
bsf STATUS,RP0
movlw ~I2C_MASK
iorwf I2C_PORT,f
bcf STATUS,RP0
return
;; -------------------------------------
i2c_start
bsf STATUS,RP0
bcf I2C_SDA
nop
bcf I2C_SCL
bcf STATUS,RP0
return
;; ------------------
i2c_restart
bsf STATUS,RP0
bsf I2C_SDA
nop
bsf I2C_SCL
nop
nop
nop
bcf I2C_SDA
nop
bcf I2C_SCL
bcf STATUS,RP0
return
;; ------------------
i2c_stop
bsf STATUS,RP0
bsf I2C_SCL
nop
bsf I2C_SDA
bcf STATUS,RP0
return
;; ------------------
i2c_send_byte
movwf I2C_BYTE
movlw .8
movwf I2C_BIT_CNT
bsf STATUS,RP0
i2c_send_byte_next
btfss I2C_BYTE,7
bcf I2C_SDA
btfsc I2C_BYTE,7
bsf I2C_SDA
nop
bsf I2C_SCL
nop
nop
bcf I2C_SCL
rlf I2C_BYTE,f
decfsz I2C_BIT_CNT,f
goto i2c_send_byte_next
nop
nop
bsf I2C_SDA
bsf I2C_SCL
bcf STATUS,RP0
movf I2C_PORT,w
bsf STATUS,RP0
bcf I2C_SCL
bcf I2C_SDA
bcf STATUS,RP0
andlw I2C_SDA_MASK
movwf I2C_BYTE
swapf I2C_BYTE,f
return
;; ------------------
i2c_recv_byte
clrf I2C_BYTE
movlw .8
movwf I2C_BIT_CNT
bsf STATUS,RP0
bsf I2C_SDA
i2c_recv_byte_loop
bsf I2C_SCL
bcf STATUS,RP0
btfsc I2C_SDA
bsf I2C_BYTE,0
bsf STATUS,RP0
bcf I2C_SCL
decfsz I2C_BIT_CNT,f
goto i2c_recv_byte_next
bcf I2C_SDA
bcf STATUS,RP0
return
i2c_recv_byte_next
bcf STATUS,C
rlf I2C_BYTE,f
goto i2c_recv_byte_loop
;; ------------------
i2c_ack
bsf STATUS,RP0
bcf I2C_SDA
bsf I2C_SCL
nop
nop
bcf I2C_SCL
bcf STATUS,RP0
return
;; ------------------
i2c_nack
bsf STATUS,RP0
bsf I2C_SDA
bsf I2C_SCL
nop
nop
bcf I2C_SCL
bcf I2C_SDA
bcf STATUS,RP0
return
;; -------------------------------------
|
