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
|
/* -*- c++ -*- */
/*
* Copyright 2003 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio 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 2, or (at your option)
* any later version.
*
* GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "i2c.h"
#include "fx2regs.h"
#include <string.h>
// issue a stop bus cycle and wait for completion
// returns non-zero if successful, else 0
unsigned char
i2c_read (unsigned char addr, xdata unsigned char *buf, unsigned char len)
{
volatile unsigned char junk;
if (len == 0) // reading zero bytes always works
return 1;
// memset (buf, 0, len); // FIXME, remove
while (I2CS & bmSTOP) // wait for stop to clear
;
I2CS = bmSTART;
I2DAT = (addr << 1) | 1; // write address and direction (1's the read bit)
while ((I2CS & bmDONE) == 0)
;
if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
goto fail;
if (len == 1)
I2CS |= bmLASTRD;
junk = I2DAT; // trigger the first read cycle
#if 1
while (len != 1){
while ((I2CS & bmDONE) == 0)
;
if (I2CS & bmBERR)
goto fail;
len--;
if (len == 1)
I2CS |= bmLASTRD;
*buf++ = I2DAT; // get data, trigger another read
}
#endif
// wait for final byte
while ((I2CS & bmDONE) == 0)
;
if (I2CS & bmBERR)
goto fail;
I2CS |= bmSTOP;
*buf = I2DAT;
return 1;
fail:
I2CS |= bmSTOP;
return 0;
}
// returns non-zero if successful, else 0
unsigned char
i2c_write (unsigned char addr, xdata const unsigned char *buf, unsigned char len)
{
while (I2CS & bmSTOP) // wait for stop to clear
;
I2CS = bmSTART;
I2DAT = (addr << 1) | 0; // write address and direction (0's the write bit)
while ((I2CS & bmDONE) == 0)
;
if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
goto fail;
while (len > 0){
I2DAT = *buf++;
len--;
while ((I2CS & bmDONE) == 0)
;
if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
goto fail;
}
I2CS |= bmSTOP;
return 1;
fail:
I2CS |= bmSTOP;
return 0;
}
|