source: trunk/FirmwareFX2/fx2/i2c.c@ 128

Last change on this file since 128 was 4, checked in by demin, 15 years ago

initial commit

File size: 3.0 KB
Line 
1/* -*- c++ -*- */
2/*-----------------------------------------------------------------------------
3 * I2C read/write functions for FX2
4 *-----------------------------------------------------------------------------
5 * Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,
6 * Copyright 2003 Free Software Foundation, Inc.
7 *-----------------------------------------------------------------------------
8 * This code is part of usbjtag. usbjtag is free software; you can redistribute
9 * it and/or modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the License,
11 * or (at your option) any later version. usbjtag is distributed in the hope
12 * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
13 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details. You should have received a
15 * copy of the GNU General Public License along with this program in the file
16 * COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin
17 * St, Fifth Floor, Boston, MA 02110-1301 USA
18 *-----------------------------------------------------------------------------
19 */
20
21#include "i2c.h"
22#include "fx2regs.h"
23#include <string.h>
24
25
26// issue a stop bus cycle and wait for completion
27
28
29// returns non-zero if successful, else 0
30unsigned char
31i2c_read (unsigned char addr, xdata unsigned char *buf, unsigned char len)
32{
33 volatile unsigned char junk;
34
35 if (len == 0) // reading zero bytes always works
36 return 1;
37
38 while (I2CS & bmSTOP) // wait for stop to clear
39 ;
40
41 I2CS = bmSTART;
42 I2DAT = (addr << 1) | 1; // write address and direction (1's the read bit)
43
44 while ((I2CS & bmDONE) == 0)
45 ;
46
47 if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
48 goto fail;
49
50 if (len == 1)
51 I2CS |= bmLASTRD;
52
53 junk = I2DAT; // trigger the first read cycle
54
55 while (--len != 0){
56 while ((I2CS & bmDONE) == 0)
57 ;
58
59 if (I2CS & bmBERR)
60 goto fail;
61
62 if (len == 1)
63 I2CS |= bmLASTRD;
64
65 *buf++ = I2DAT; // get data, trigger another read
66 }
67
68 // wait for final byte
69
70 while ((I2CS & bmDONE) == 0)
71 ;
72
73 if (I2CS & bmBERR)
74 goto fail;
75
76 I2CS |= bmSTOP;
77 *buf = I2DAT;
78
79 return 1;
80
81 fail:
82 I2CS |= bmSTOP;
83 return 0;
84}
85
86
87
88// returns non-zero if successful, else 0
89unsigned char
90i2c_write (unsigned char addr, xdata const unsigned char *buf, unsigned char len)
91{
92 while (I2CS & bmSTOP) // wait for stop to clear
93 ;
94
95 I2CS = bmSTART;
96 I2DAT = (addr << 1) | 0; // write address and direction (0's the write bit)
97
98 while ((I2CS & bmDONE) == 0)
99 ;
100
101 if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
102 goto fail;
103
104 while (len > 0){
105 I2DAT = *buf++;
106 len--;
107
108 while ((I2CS & bmDONE) == 0)
109 ;
110
111 if ((I2CS & bmBERR) || (I2CS & bmACK) == 0) // no device answered...
112 goto fail;
113 }
114
115 I2CS |= bmSTOP;
116 return 1;
117
118 fail:
119 I2CS |= bmSTOP;
120 return 0;
121}
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