summaryrefslogtreecommitdiff
path: root/software/ihu/i2c.inc
blob: de798364db9e25cbb1820b020b905cbdef010353 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
  ;;
  ;;  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_start
  bsf       STATUS,RP0
  bcf       TRISB,I2C_SDA
  nop
  bcf       TRISB,I2C_SCL
  bcf       STATUS,RP0
  return
  
  ;; ------------------
i2c_restart
  bsf       STATUS,RP0
  bsf       TRISB,I2C_SDA
  nop
  bsf       TRISB,I2C_SCL
  nop
  nop
  nop
  bcf       TRISB,I2C_SDA
  nop
  bcf       TRISB,I2C_SCL
  bcf       STATUS,RP0
  return
  
  ;; ------------------
i2c_stop
  bsf       STATUS,RP0
  bsf       TRISB,I2C_SCL
  nop
  bsf       TRISB,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       TRISB,I2C_SDA
  btfsc     I2C_BYTE,7
  bsf       TRISB,I2C_SDA
  nop
  bsf       TRISB,I2C_SCL
  nop
  nop
  bcf       TRISB,I2C_SCL
  rlf       I2C_BYTE,f
  decfsz    I2C_BIT_CNT,f
  goto      i2c_send_byte_next

  nop
  nop
  bsf       TRISB,I2C_SDA
  bsf       TRISB,I2C_SCL
  bcf       STATUS,RP0
  movf      PORTB,w
  bsf       STATUS,RP0
  bcf       TRISB,I2C_SCL
  bcf       TRISB,I2C_SDA
  bcf       STATUS,RP0
  andlw     b'00010000'
  movwf     I2C_BYTE
  swapf     I2C_BYTE,f
  return

  ;; ------------------
i2c_recv_byte
  clrf      I2C_BYTE
  movlw     .8
  movwf     I2C_BIT_CNT
  bsf       STATUS,RP0
  bsf       TRISB,I2C_SDA
i2c_recv_byte_loop
  bsf       TRISB,I2C_SCL
  bcf       STATUS,RP0
  btfsc     PORTB,I2C_SDA
  bsf       I2C_BYTE,0
  bsf       STATUS,RP0
  bcf       TRISB,I2C_SCL
  decfsz    I2C_BIT_CNT,f
  goto      i2c_recv_byte_next

  bcf       TRISB,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       TRISB,I2C_SDA
  bsf       TRISB,I2C_SCL
  nop
  nop
  bcf       TRISB,I2C_SCL
  bcf       STATUS,RP0
  return
  
  ;; ------------------
i2c_nack
  bsf       STATUS,RP0
  bsf       TRISB,I2C_SDA
  bsf       TRISB,I2C_SCL
  nop
  nop
  bcf       TRISB,I2C_SCL
  bcf       TRISB,I2C_SDA
  bcf       STATUS,RP0
  return

  ;; -------------------------------------