source: arduino-1-6-7/trunk/fuentes/arduino-ide-amd64/hardware/tools/avr/avr/include/avr/fuse.h @ 4837

Last change on this file since 4837 was 4837, checked in by daduve, 2 years ago

Adding new version

File size: 9.0 KB
Line 
1/* Copyright (c) 2007, Atmel Corporation
2   All rights reserved.
3
4   Redistribution and use in source and binary forms, with or without
5   modification, are permitted provided that the following conditions are met:
6
7   * Redistributions of source code must retain the above copyright
8     notice, this list of conditions and the following disclaimer.
9
10   * Redistributions in binary form must reproduce the above copyright
11     notice, this list of conditions and the following disclaimer in
12     the documentation and/or other materials provided with the
13     distribution.
14
15   * Neither the name of the copyright holders nor the names of
16     contributors may be used to endorse or promote products derived
17     from this software without specific prior written permission.
18
19  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
23  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  POSSIBILITY OF SUCH DAMAGE. */
30
31/* $Id$ */
32
33/* avr/fuse.h - Fuse API */
34
35#ifndef _AVR_FUSE_H_
36#define _AVR_FUSE_H_ 1
37
38/* This file must be explicitly included by <avr/io.h>. */
39#if !defined(_AVR_IO_H_)
40#error "You must #include <avr/io.h> and not <avr/fuse.h> by itself."
41#endif
42
43
44/** \file */
45/** \defgroup avr_fuse <avr/fuse.h>: Fuse Support
46
47    \par Introduction
48
49    The Fuse API allows a user to specify the fuse settings for the specific
50    AVR device they are compiling for. These fuse settings will be placed
51    in a special section in the ELF output file, after linking.
52
53    Programming tools can take advantage of the fuse information embedded in
54    the ELF file, by extracting this information and determining if the fuses
55    need to be programmed before programming the Flash and EEPROM memories.
56    This also allows a single ELF file to contain all the
57    information needed to program an AVR.
58
59    To use the Fuse API, include the <avr/io.h> header file, which in turn
60    automatically includes the individual I/O header file and the <avr/fuse.h>
61    file. These other two files provides everything necessary to set the AVR
62    fuses.
63   
64    \par Fuse API
65   
66    Each I/O header file must define the FUSE_MEMORY_SIZE macro which is
67    defined to the number of fuse bytes that exist in the AVR device.
68   
69    A new type, __fuse_t, is defined as a structure. The number of fields in
70    this structure are determined by the number of fuse bytes in the
71    FUSE_MEMORY_SIZE macro.
72   
73    If FUSE_MEMORY_SIZE == 1, there is only a single field: byte, of type
74    unsigned char.
75   
76    If FUSE_MEMORY_SIZE == 2, there are two fields: low, and high, of type
77    unsigned char.
78   
79    If FUSE_MEMORY_SIZE == 3, there are three fields: low, high, and extended,
80    of type unsigned char.
81   
82    If FUSE_MEMORY_SIZE > 3, there is a single field: byte, which is an array
83    of unsigned char with the size of the array being FUSE_MEMORY_SIZE.
84   
85    A convenience macro, FUSEMEM, is defined as a GCC attribute for a
86    custom-named section of ".fuse".
87   
88    A convenience macro, FUSES, is defined that declares a variable, __fuse, of
89    type __fuse_t with the attribute defined by FUSEMEM. This variable
90    allows the end user to easily set the fuse data.
91
92    \note If a device-specific I/O header file has previously defined FUSEMEM,
93    then FUSEMEM is not redefined. If a device-specific I/O header file has
94    previously defined FUSES, then FUSES is not redefined.
95
96    Each AVR device I/O header file has a set of defined macros which specify the
97    actual fuse bits available on that device. The AVR fuses have inverted
98    values, logical 1 for an unprogrammed (disabled) bit and logical 0 for a
99    programmed (enabled) bit. The defined macros for each individual fuse
100    bit represent this in their definition by a bit-wise inversion of a mask.
101    For example, the FUSE_EESAVE fuse in the ATmega128 is defined as:
102    \code
103    #define FUSE_EESAVE      ~_BV(3)
104    \endcode
105    \note The _BV macro creates a bit mask from a bit number. It is then
106    inverted to represent logical values for a fuse memory byte.
107   
108    To combine the fuse bits macros together to represent a whole fuse byte,
109    use the bitwise AND operator, like so:
110    \code
111    (FUSE_BOOTSZ0 & FUSE_BOOTSZ1 & FUSE_EESAVE & FUSE_SPIEN & FUSE_JTAGEN)
112    \endcode
113   
114    Each device I/O header file also defines macros that provide default values
115    for each fuse byte that is available. LFUSE_DEFAULT is defined for a Low
116    Fuse byte. HFUSE_DEFAULT is defined for a High Fuse byte. EFUSE_DEFAULT
117    is defined for an Extended Fuse byte.
118   
119    If FUSE_MEMORY_SIZE > 3, then the I/O header file defines macros that
120    provide default values for each fuse byte like so:
121    FUSE0_DEFAULT
122    FUSE1_DEFAULT
123    FUSE2_DEFAULT
124    FUSE3_DEFAULT
125    FUSE4_DEFAULT
126    ....
127   
128    \par API Usage Example
129   
130    Putting all of this together is easy. Using C99's designated initializers:
131   
132    \code
133    #include <avr/io.h>
134
135    FUSES =
136    {
137        .low = LFUSE_DEFAULT,
138        .high = (FUSE_BOOTSZ0 & FUSE_BOOTSZ1 & FUSE_EESAVE & FUSE_SPIEN & FUSE_JTAGEN),
139        .extended = EFUSE_DEFAULT,
140    };
141
142    int main(void)
143    {
144        return 0;
145    }
146    \endcode
147   
148    Or, using the variable directly instead of the FUSES macro,
149   
150    \code
151    #include <avr/io.h>
152
153    __fuse_t __fuse __attribute__((section (".fuse"))) =
154    {
155        .low = LFUSE_DEFAULT,
156        .high = (FUSE_BOOTSZ0 & FUSE_BOOTSZ1 & FUSE_EESAVE & FUSE_SPIEN & FUSE_JTAGEN),
157        .extended = EFUSE_DEFAULT,
158    };
159
160    int main(void)
161    {
162        return 0;
163    }
164    \endcode
165   
166    If you are compiling in C++, you cannot use the designated intializers so
167    you must do:
168
169    \code
170    #include <avr/io.h>
171
172    FUSES =
173    {
174        LFUSE_DEFAULT, // .low
175        (FUSE_BOOTSZ0 & FUSE_BOOTSZ1 & FUSE_EESAVE & FUSE_SPIEN & FUSE_JTAGEN), // .high
176        EFUSE_DEFAULT, // .extended
177    };
178
179    int main(void)
180    {
181        return 0;
182    }
183    \endcode
184   
185   
186    However there are a number of caveats that you need to be aware of to
187    use this API properly.
188   
189    Be sure to include <avr/io.h> to get all of the definitions for the API.
190    The FUSES macro defines a global variable to store the fuse data. This
191    variable is assigned to its own linker section. Assign the desired fuse
192    values immediately in the variable initialization.
193   
194    The .fuse section in the ELF file will get its values from the initial
195    variable assignment ONLY. This means that you can NOT assign values to
196    this variable in functions and the new values will not be put into the
197    ELF .fuse section.
198   
199    The global variable is declared in the FUSES macro has two leading
200    underscores, which means that it is reserved for the "implementation",
201    meaning the library, so it will not conflict with a user-named variable.
202   
203    You must initialize ALL fields in the __fuse_t structure. This is because
204    the fuse bits in all bytes default to a logical 1, meaning unprogrammed.
205    Normal uninitialized data defaults to all locgial zeros. So it is vital that
206    all fuse bytes are initialized, even with default data. If they are not,
207    then the fuse bits may not programmed to the desired settings.
208   
209    Be sure to have the -mmcu=<em>device</em> flag in your compile command line and
210    your linker command line to have the correct device selected and to have
211    the correct I/O header file included when you include <avr/io.h>.
212
213    You can print out the contents of the .fuse section in the ELF file by
214    using this command line:
215    \code
216    avr-objdump -s -j .fuse <ELF file>
217    \endcode
218    The section contents shows the address on the left, then the data going from
219    lower address to a higher address, left to right.
220
221*/
222
223#if !(defined(__ASSEMBLER__) || defined(__DOXYGEN__))
224
225#ifndef FUSEMEM
226#define FUSEMEM  __attribute__((__used__, __section__ (".fuse")))
227#endif
228
229#if FUSE_MEMORY_SIZE > 3
230
231typedef struct
232{
233    unsigned char byte[FUSE_MEMORY_SIZE];
234} __fuse_t;
235
236
237#elif FUSE_MEMORY_SIZE == 3
238
239typedef struct
240{
241    unsigned char low;
242    unsigned char high;
243    unsigned char extended;
244} __fuse_t;
245
246#elif FUSE_MEMORY_SIZE == 2
247
248typedef struct
249{
250    unsigned char low;
251    unsigned char high;
252} __fuse_t;
253
254#elif FUSE_MEMORY_SIZE == 1
255
256typedef struct
257{
258    unsigned char byte;
259} __fuse_t;
260
261#endif
262
263#if !defined(FUSES)
264  #if defined(__AVR_XMEGA__)
265    #define FUSES NVM_FUSES_t __fuse FUSEMEM
266  #else
267    #define FUSES __fuse_t __fuse FUSEMEM
268  #endif
269#endif
270
271
272#endif /* !(__ASSEMBLER__ || __DOXYGEN__) */
273
274#endif /* _AVR_FUSE_H_ */
Note: See TracBrowser for help on using the repository browser.