NAME
A simple project - At this point, you should have the GNU tools
configured, built, and installed on your system. In this chapter, we
present a simple example of using the GNU tools in an AVR project.
After reading this chapter, you should have a better feel as to how the
tools are used and how a Makefile can be configured.
The Project
This project will use the pulse-width modulator (PWM) to ramp an LED on
and off every two seconds. An AT90S2313 processor will be used as the
controller. The circuit for this demonstration is shown in the
schematic diagram. If you have a development kit, you should be able to
use it, rather than build the circuit, for this project.
Note:
Meanwhile, the AT90S2313 became obsolete. Either use its successor,
the (pin-compatible) ATtiny2313 for the project, or perhaps the
ATmega8 or one of its successors (ATmega48/88/168) which have
become quite popular since the original demo project had been
established. For all these more modern devices, it is no longer
necessary to use an external crystal for clocking as they ship with
the internal 1 MHz oscillator enabled, so C1, C2, and Q1 can be
omitted. Normally, for this experiment, the external circuitry on
/RESET (R1, C3) can be omitted as well, leaving only the AVR, the
LED, the bypass capacitor C4, and perhaps R2. For the
ATmega8/48/88/168, use PB1 (pin 15 at the DIP-28 package) to
connect the LED to. Additionally, this demo has been ported to many
different other AVRs. The location of the respective OC pin varies
between different AVRs, and it is mandated by the AVR hardware.
Schematic of circuit for demo projectSchematic of circuit for demo
project
The source code is given in demo.c. For the sake of this example,
create a file called demo.c containing this source code. Some of the
more important parts of the code are:
Note [1]:
As the AVR microcontroller series has been developed during the
past years, new features have been added over time. Even though the
basic concepts of the timer/counter1 are still the same as they
used to be back in early 2001 when this simple demo was written
initially, the names of registers and bits have been changed
slightly to reflect the new features. Also, the port and pin
mapping of the output compare match 1A (or 1 for older devices) pin
which is used to control the LED varies between different AVRs. The
file iocompat.h tries to abstract between all this differences
using some preprocessor #ifdef statements, so the actual program
itself can operate on a common set of symbolic names. The macros
defined by that file are:
o OCR the name of the OCR register used to control the PWM (usually
either OCR1 or OCR1A)
o DDROC the name of the DDR (data direction register) for the OC output
o OC1 the pin number of the OC1[A] output within its port
o TIMER1_TOP the TOP value of the timer used for the PWM (1023 for
10-bit PWMs, 255 for devices that can only handle an 8-bit PWM)
o TIMER1_PWM_INIT the initialization bits to be set into control
register 1A in order to setup 10-bit (or 8-bit) phase and frequency
correct PWM mode
o TIMER1_CLOCKSOURCE the clock bits to set in the respective control
register to start the PWM timer; usually the timer runs at full CPU
clock for 10-bit PWMs, while it runs on a prescaled clock for 8-bit
PWMs
Note [2]:
ISR() is a macro that marks the function as an interrupt routine.
In this case, the function will get called when timer 1 overflows.
Setting up interrupts is explained in greater detail in
<avr/interrupt.h>: Interrupts.
Note [3]:
The PWM is being used in 10-bit mode, so we need a 16-bit variable
to remember the current value.
Note [4]:
This section determines the new value of the PWM.
Note [5]:
Here's where the newly computed value is loaded into the PWM
register. Since we are in an interrupt routine, it is safe to use a
16-bit assignment to the register. Outside of an interrupt, the
assignment should only be performed with interrupts disabled if
there's a chance that an interrupt routine could also access this
register (or another register that uses TEMP), see the appropriate
FAQ entry.
Note [6]:
This routine gets called after a reset. It initializes the PWM and
enables interrupts.
Note [7]:
The main loop of the program does nothing -- all the work is done
by the interrupt routine! The sleep_mode() puts the processor on
sleep until the next interrupt, to conserve power. Of course, that
probably won't be noticable as we are still driving a LED, it is
merely mentioned here to demonstrate the basic principle.
Note [8]:
Early AVR devices saturate their outputs at rather low currents
when sourcing current, so the LED can be connected directly, the
resulting current through the LED will be about 15 mA. For modern
parts (at least for the ATmega 128), however Atmel has drastically
increased the IO source capability, so when operating at 5 V Vcc,
R2 is needed. Its value should be about 150 Ohms. When operating
the circuit at 3 V, it can still be omitted though.
The Source Code
/*
* ----------------------------------------------------------------------------
* 'THE BEER-WARE LICENSE' (Revision 42):
* <joerg@FreeBSD.ORG> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Joerg Wunsch
* ----------------------------------------------------------------------------
*
* Simple AVR demonstration. Controls a LED that can be directly
* connected from OC1/OC1A to GND. The brightness of the LED is
* controlled with the PWM. After each period of the PWM, the PWM
* value is either incremented or decremented, that's all.
*
* $Id: demo.c,v 1.9 2006/01/05 21:30:10 joerg_wunsch Exp $
*/
#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include 'iocompat.h' /* Note [1] */
enum { UP, DOWN };
ISR (TIMER1_OVF_vect) /* Note [2] */
{
static uint16_t pwm; /* Note [3] */
static uint8_t direction;
switch (direction) /* Note [4] */
{
case UP:
if (++pwm == TIMER1_TOP)
direction = DOWN;
break;
case DOWN:
if (--pwm == 0)
direction = UP;
break;
}
OCR = pwm; /* Note [5] */
}
void
ioinit (void) /* Note [6] */
{
/* Timer 1 is 10-bit PWM (8-bit PWM on some ATtinys). */
TCCR1A = TIMER1_PWM_INIT;
/*
* Start timer 1.
*
* NB: TCCR1A and TCCR1B could actually be the same register, so
* take care to not clobber it.
*/
TCCR1B |= TIMER1_CLOCKSOURCE;
/*
* Run any device-dependent timer 1 setup hook if present.
*/
#if defined(TIMER1_SETUP_HOOK)
TIMER1_SETUP_HOOK();
#endif
/* Set PWM value to 0. */
OCR = 0;
/* Enable OC1 as output. */
DDROC = _BV (OC1);
/* Enable timer 1 overflow interrupt. */
TIMSK = _BV (TOIE1);
sei ();
}
int
main (void)
{
ioinit ();
/* loop forever, the interrupts are doing the rest */
for (;;) /* Note [7] */
sleep_mode();
return (0);
}
Compiling and Linking
This first thing that needs to be done is compile the source. When
compiling, the compiler needs to know the processor type so the -mmcu
option is specified. The -Os option will tell the compiler to optimize
the code for efficient space usage (at the possible expense of code
execution speed). The -g is used to embed debug info. The debug info is
useful for disassemblies and doesn't end up in the .hex files, so I
usually specify it. Finally, the -c tells the compiler to compile and
stop -- don't link. This demo is small enough that we could compile and
link in one step. However, real-world projects will have several
modules and will typically need to break up the building of the project
into several compiles and one link.
$ avr-gcc -g -Os -mmcu=atmega8 -c demo.c
The compilation will create a demo.o file. Next we link it into a
binary called demo.elf.
$ avr-gcc -g -mmcu=atmega8 -o demo.elf demo.o
It is important to specify the MCU type when linking. The compiler uses
the -mmcu option to choose start-up files and run-time libraries that
get linked together. If this option isn't specified, the compiler
defaults to the 8515 processor environment, which is most certainly
what you didn't want.
Examining the Object File
Now we have a binary file. Can we do anything useful with it (besides
put it into the processor?) The GNU Binutils suite is made up of many
useful tools for manipulating object files that get generated. One tool
is avr-objdump, which takes information from the object file and
displays it in many useful ways. Typing the command by itself will
cause it to list out its options.
For instance, to get a feel of the application's size, the -h option
can be used. The output of this option shows how much space is used in
each of the sections (the .stab and .stabstr sections hold the
debugging information and won't make it into the ROM file).
An even more useful option is -S. This option disassembles the binary
file and intersperses the source code in the output! This method is
much better, in my opinion, than using the -S with the compiler because
this listing includes routines from the libraries and the vector table
contents. Also, all the 'fix-ups' have been satisfied. In other words,
the listing generated by this option reflects the actual code that the
processor will run.
$ avr-objdump -h -S demo.elf > demo.lst
Here's the output as saved in the demo.lst file:
demo.elf: file format elf32-avr
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 000000fa 00000000 00000000 00000074 2**1
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .bss 00000003 00800060 00800060 0000016e 2**0
ALLOC
2 .stab 00000b70 00000000 00000000 00000170 2**2
CONTENTS, READONLY, DEBUGGING
3 .stabstr 00000788 00000000 00000000 00000ce0 2**0
CONTENTS, READONLY, DEBUGGING
Disassembly of section .text:
00000000 <__vectors>:
0: 12 c0 rjmp .+36 ; 0x26 <__ctors_end>
2: 76 c0 rjmp .+236 ; 0xf0 <__bad_interrupt>
4: 75 c0 rjmp .+234 ; 0xf0 <__bad_interrupt>
6: 74 c0 rjmp .+232 ; 0xf0 <__bad_interrupt>
8: 73 c0 rjmp .+230 ; 0xf0 <__bad_interrupt>
a: 72 c0 rjmp .+228 ; 0xf0 <__bad_interrupt>
c: 71 c0 rjmp .+226 ; 0xf0 <__bad_interrupt>
e: 70 c0 rjmp .+224 ; 0xf0 <__bad_interrupt>
10: 1a c0 rjmp .+52 ; 0x46 <__vector_8>
12: 6e c0 rjmp .+220 ; 0xf0 <__bad_interrupt>
14: 6d c0 rjmp .+218 ; 0xf0 <__bad_interrupt>
16: 6c c0 rjmp .+216 ; 0xf0 <__bad_interrupt>
18: 6b c0 rjmp .+214 ; 0xf0 <__bad_interrupt>
1a: 6a c0 rjmp .+212 ; 0xf0 <__bad_interrupt>
1c: 69 c0 rjmp .+210 ; 0xf0 <__bad_interrupt>
1e: 68 c0 rjmp .+208 ; 0xf0 <__bad_interrupt>
20: 67 c0 rjmp .+206 ; 0xf0 <__bad_interrupt>
22: 66 c0 rjmp .+204 ; 0xf0 <__bad_interrupt>
24: 65 c0 rjmp .+202 ; 0xf0 <__bad_interrupt>
00000026 <__ctors_end>:
26: 11 24 eor r1, r1
28: 1f be out 0x3f, r1 ; 63
2a: cf e5 ldi r28, 0x5F ; 95
2c: d4 e0 ldi r29, 0x04 ; 4
2e: de bf out 0x3e, r29 ; 62
30: cd bf out 0x3d, r28 ; 61
00000032 <__do_clear_bss>:
32: 10 e0 ldi r17, 0x00 ; 0
34: a0 e6 ldi r26, 0x60 ; 96
36: b0 e0 ldi r27, 0x00 ; 0
38: 01 c0 rjmp .+2 ; 0x3c <.do_clear_bss_start>
0000003a <.do_clear_bss_loop>:
3a: 1d 92 st X+, r1
0000003c <.do_clear_bss_start>:
3c: a3 36 cpi r26, 0x63 ; 99
3e: b1 07 cpc r27, r17
40: e1 f7 brne .-8 ; 0x3a <.do_clear_bss_loop>
42: 4d d0 rcall .+154 ; 0xde <main>
44: 56 c0 rjmp .+172 ; 0xf2 <exit>
00000046 <__vector_8>:
#include "iocompat.h" /* Note [1] */
enum { UP, DOWN };
ISR (TIMER1_OVF_vect) /* Note [2] */
{
46: 1f 92 push r1
48: 0f 92 push r0
4a: 0f b6 in r0, 0x3f ; 63
4c: 0f 92 push r0
4e: 11 24 eor r1, r1
50: 2f 93 push r18
52: 3f 93 push r19
54: 8f 93 push r24
static uint16_t pwm; /* Note [3] */
static uint8_t direction;
switch (direction) /* Note [4] */
56: 80 91 60 00 lds r24, 0x0060
5a: 88 23 and r24, r24
5c: c1 f4 brne .+48 ; 0x8e <__vector_8+0x48>
{
case UP:
if (++pwm == TIMER1_TOP)
5e: 20 91 61 00 lds r18, 0x0061
62: 30 91 62 00 lds r19, 0x0062
66: 2f 5f subi r18, 0xFF ; 255
68: 3f 4f sbci r19, 0xFF ; 255
6a: 30 93 62 00 sts 0x0062, r19
6e: 20 93 61 00 sts 0x0061, r18
72: 83 e0 ldi r24, 0x03 ; 3
74: 2f 3f cpi r18, 0xFF ; 255
76: 38 07 cpc r19, r24
78: 09 f1 breq .+66 ; 0xbc <__vector_8+0x76>
if (--pwm == 0)
direction = UP;
break;
}
OCR = pwm; /* Note [5] */
7a: 3b bd out 0x2b, r19 ; 43
7c: 2a bd out 0x2a, r18 ; 42
}
7e: 8f 91 pop r24
80: 3f 91 pop r19
82: 2f 91 pop r18
84: 0f 90 pop r0
86: 0f be out 0x3f, r0 ; 63
88: 0f 90 pop r0
8a: 1f 90 pop r1
8c: 18 95 reti
ISR (TIMER1_OVF_vect) /* Note [2] */
{
static uint16_t pwm; /* Note [3] */
static uint8_t direction;
switch (direction) /* Note [4] */
8e: 81 30 cpi r24, 0x01 ; 1
90: 29 f0 breq .+10 ; 0x9c <__vector_8+0x56>
92: 20 91 61 00 lds r18, 0x0061
96: 30 91 62 00 lds r19, 0x0062
9a: ef cf rjmp .-34 ; 0x7a <__vector_8+0x34>
if (++pwm == TIMER1_TOP)
direction = DOWN;
break;
case DOWN:
if (--pwm == 0)
9c: 20 91 61 00 lds r18, 0x0061
a0: 30 91 62 00 lds r19, 0x0062
a4: 21 50 subi r18, 0x01 ; 1
a6: 30 40 sbci r19, 0x00 ; 0
a8: 30 93 62 00 sts 0x0062, r19
ac: 20 93 61 00 sts 0x0061, r18
b0: 21 15 cp r18, r1
b2: 31 05 cpc r19, r1
b4: 11 f7 brne .-60 ; 0x7a <__vector_8+0x34>
direction = UP;
b6: 10 92 60 00 sts 0x0060, r1
ba: df cf rjmp .-66 ; 0x7a <__vector_8+0x34>
switch (direction) /* Note [4] */
{
case UP:
if (++pwm == TIMER1_TOP)
direction = DOWN;
bc: 81 e0 ldi r24, 0x01 ; 1
be: 80 93 60 00 sts 0x0060, r24
c2: db cf rjmp .-74 ; 0x7a <__vector_8+0x34>
000000c4 <ioinit>:
void
ioinit (void) /* Note [6] */
{
/* Timer 1 is 10-bit PWM (8-bit PWM on some ATtinys). */
TCCR1A = TIMER1_PWM_INIT;
c4: 83 e8 ldi r24, 0x83 ; 131
c6: 8f bd out 0x2f, r24 ; 47
* Start timer 1.
*
* NB: TCCR1A and TCCR1B could actually be the same register, so
* take care to not clobber it.
*/
TCCR1B |= TIMER1_CLOCKSOURCE;
c8: 8e b5 in r24, 0x2e ; 46
ca: 81 60 ori r24, 0x01 ; 1
cc: 8e bd out 0x2e, r24 ; 46
#if defined(TIMER1_SETUP_HOOK)
TIMER1_SETUP_HOOK();
#endif
/* Set PWM value to 0. */
OCR = 0;
ce: 1b bc out 0x2b, r1 ; 43
d0: 1a bc out 0x2a, r1 ; 42
/* Enable OC1 as output. */
DDROC = _BV (OC1);
d2: 82 e0 ldi r24, 0x02 ; 2
d4: 87 bb out 0x17, r24 ; 23
/* Enable timer 1 overflow interrupt. */
TIMSK = _BV (TOIE1);
d6: 84 e0 ldi r24, 0x04 ; 4
d8: 89 bf out 0x39, r24 ; 57
sei ();
da: 78 94 sei
}
dc: 08 95 ret
000000de <main>:
int
main (void)
{
ioinit ();
de: f2 df rcall .-28 ; 0xc4 <ioinit>
/* loop forever, the interrupts are doing the rest */
for (;;) /* Note [7] */
sleep_mode();
e0: 85 b7 in r24, 0x35 ; 53
e2: 80 68 ori r24, 0x80 ; 128
e4: 85 bf out 0x35, r24 ; 53
e6: 88 95 sleep
e8: 85 b7 in r24, 0x35 ; 53
ea: 8f 77 andi r24, 0x7F ; 127
ec: 85 bf out 0x35, r24 ; 53
ee: f8 cf rjmp .-16 ; 0xe0 <main+0x2>
000000f0 <__bad_interrupt>:
f0: 87 cf rjmp .-242 ; 0x0 <__vectors>
000000f2 <exit>:
ASSEMBLY_CLIB_SECTION
.global _U(exit)
.type _U(exit), "function"
_U(exit):
cli
f2: f8 94 cli
XJMP _U(_exit)
f4: 00 c0 rjmp .+0 ; 0xf6 <_exit>
000000f6 <_exit>:
f6: f8 94 cli
000000f8 <__stop_program>:
f8: ff cf rjmp .-2 ; 0xf8 <__stop_program>
Linker Map Files
avr-objdump is very useful, but sometimes it's necessary to see
information about the link that can only be generated by the linker. A
map file contains this information. A map file is useful for monitoring
the sizes of your code and data. It also shows where modules are loaded
and which modules were loaded from libraries. It is yet another view of
your application. To get a map file, I usually add -Wl,-Map,demo.map to
my link command. Relink the application using the following command to
generate demo.map (a portion of which is shown below).
$ avr-gcc -g -mmcu=atmega8 -Wl,-Map,demo.map -o demo.elf demo.o
Some points of interest in the demo.map file are:
*(.rela.plt)
*(.vectors)
.vectors 0x00000000 0x26 /build/buildd/avr-libc-1.6.8/avr/lib/avr4/atmega8/crtm8.o
0x00000000 __vectors
0x00000000 __vector_default
*(.vectors)
*(.progmem.gcc*)
*(.progmem*)
0x00000026 . = ALIGN (0x2)
0x00000026 __trampolines_start = .
*(.trampolines)
.trampolines 0x00000026 0x0 linker stubs
*(.trampolines*)
0x00000026 __trampolines_end = .
*(.jumptables)
*(.jumptables*)
*(.lowtext)
*(.lowtext*)
0x00000026 __ctors_start = .
The .text segment (where program instructions are stored) starts at
location 0x0.
*(.fini2)
*(.fini2)
*(.fini1)
*(.fini1)
*(.fini0)
.fini0 0x000000f6 0x4 /usr/lib/gcc/avr/4.3.5/avr4/libgcc.a(_exit.o)
*(.fini0)
0x000000fa _etext = .
0x00800060 PROVIDE (__data_start, .)
*(.data)
.data 0x00800060 0x0 demo.o
.data 0x00800060 0x0 /build/buildd/avr-libc-1.6.8/avr/lib/avr4/atmega8/crtm8.o
.data 0x00800060 0x0 /build/buildd/avr-libc-1.6.8/avr/lib/avr4/exit.o
.data 0x00800060 0x0 /usr/lib/gcc/avr/4.3.5/avr4/libgcc.a(_exit.o)
.data 0x00800060 0x0 /usr/lib/gcc/avr/4.3.5/avr4/libgcc.a(_clear_bss.o)
*(.data*)
*(.rodata)
*(.rodata*)
*(.gnu.linkonce.d*)
0x00800060 . = ALIGN (0x2)
0x00800060 _edata = .
0x00800060 PROVIDE (__data_end, .)
0x00800060 PROVIDE (__bss_start, .)
*(.bss)
.bss 0x00800060 0x3 demo.o
.bss 0x00800063 0x0 /build/buildd/avr-libc-1.6.8/avr/lib/avr4/atmega8/crtm8.o
.bss 0x00800063 0x0 /build/buildd/avr-libc-1.6.8/avr/lib/avr4/exit.o
.bss 0x00800063 0x0 /usr/lib/gcc/avr/4.3.5/avr4/libgcc.a(_exit.o)
.bss 0x00800063 0x0 /usr/lib/gcc/avr/4.3.5/avr4/libgcc.a(_clear_bss.o)
*(.bss*)
*(COMMON)
0x00800063 PROVIDE (__bss_end, .)
0x000000fa __data_load_start = LOADADDR (.data)
0x000000fa __data_load_end = (__data_load_start + SIZEOF (.data))
0x00800063 PROVIDE (__noinit_start, .)
*(.noinit*)
0x00800063 PROVIDE (__noinit_end, .)
0x00800063 _end = .
0x00800063 PROVIDE (__heap_start, .)
*(.eeprom*)
0x00810000 __eeprom_end = .
The last address in the .text segment is location 0x114 ( denoted by
_etext ), so the instructions use up 276 bytes of FLASH.
The .data segment (where initialized static variables are stored)
starts at location 0x60, which is the first address after the register
bank on an ATmega8 processor.
The next available address in the .data segment is also location 0x60,
so the application has no initialized data.
The .bss segment (where uninitialized data is stored) starts at
location 0x60.
The next available address in the .bss segment is location 0x63, so the
application uses 3 bytes of uninitialized data.
The .eeprom segment (where EEPROM variables are stored) starts at
location 0x0.
The next available address in the .eeprom segment is also location 0x0,
so there aren't any EEPROM variables.
Generating Intel Hex Files
We have a binary of the application, but how do we get it into the
processor? Most (if not all) programmers will not accept a GNU
executable as an input file, so we need to do a little more processing.
The next step is to extract portions of the binary and save the
information into .hex files. The GNU utility that does this is called
avr-objcopy.
The ROM contents can be pulled from our project's binary and put into
the file demo.hex using the following command:
$ avr-objcopy -j .text -j .data -O ihex demo.elf demo.hex
The resulting demo.hex file contains:
:1000000012C076C075C074C073C072C071C070C0B9
:100010001AC06EC06DC06CC06BC06AC069C068C0D9
:1000200067C066C065C011241FBECFE5D4E0DEBF47
:10003000CDBF10E0A0E6B0E001C01D92A336B1072D
:10004000E1F74DD056C01F920F920FB60F921124B8
:100050002F933F938F93809160008823C1F4209168
:100060006100309162002F5F3F4F30936200209318
:10007000610083E02F3F380709F13BBD2ABD8F9116
:100080003F912F910F900FBE0F901F9018958130C8
:1000900029F02091610030916200EFCF2091610042
:1000A0003091620021503040309362002093610013
:1000B0002115310511F710926000DFCF81E08093A8
:1000C0006000DBCF83E88FBD8EB581608EBD1BBC29
:1000D0001ABC82E087BB84E089BF78940895F2DF80
:1000E00085B7806885BF889585B78F7785BFF8CF3E
:0A00F00087CFF89400C0F894FFCF0A
:00000001FF
The -j option indicates that we want the information from the .text and
.data segment extracted. If we specify the EEPROM segment, we can
generate a .hex file that can be used to program the EEPROM:
$ avr-objcopy -j .eeprom --change-section-lma .eeprom=0 -O ihex demo.elf demo_eeprom.hex
There is no demo_eeprom.hex file written, as that file would be empty.
Starting with version 2.17 of the GNU binutils, the avr-objcopy command
that used to generate the empty EEPROM files now aborts because of the
empty input section .eeprom, so these empty files are not generated. It
also signals an error to the Makefile which will be caught there, and
makes it print a message about the empty file not being generated.
Letting Make Build the Project
Rather than type these commands over and over, they can all be placed
in a make file. To build the demo project using make, save the
following in a file called Makefile.
Note:
This Makefile can only be used as input for the GNU version of
make.
PRG = demo
OBJ = demo.o
#MCU_TARGET = at90s2313
#MCU_TARGET = at90s2333
#MCU_TARGET = at90s4414
#MCU_TARGET = at90s4433
#MCU_TARGET = at90s4434
#MCU_TARGET = at90s8515
#MCU_TARGET = at90s8535
#MCU_TARGET = atmega128
#MCU_TARGET = atmega1280
#MCU_TARGET = atmega1281
#MCU_TARGET = atmega1284p
#MCU_TARGET = atmega16
#MCU_TARGET = atmega163
#MCU_TARGET = atmega164p
#MCU_TARGET = atmega165
#MCU_TARGET = atmega165p
#MCU_TARGET = atmega168
#MCU_TARGET = atmega169
#MCU_TARGET = atmega169p
#MCU_TARGET = atmega2560
#MCU_TARGET = atmega2561
#MCU_TARGET = atmega32
#MCU_TARGET = atmega324p
#MCU_TARGET = atmega325
#MCU_TARGET = atmega3250
#MCU_TARGET = atmega329
#MCU_TARGET = atmega3290
#MCU_TARGET = atmega48
#MCU_TARGET = atmega64
#MCU_TARGET = atmega640
#MCU_TARGET = atmega644
#MCU_TARGET = atmega644p
#MCU_TARGET = atmega645
#MCU_TARGET = atmega6450
#MCU_TARGET = atmega649
#MCU_TARGET = atmega6490
MCU_TARGET = atmega8
#MCU_TARGET = atmega8515
#MCU_TARGET = atmega8535
#MCU_TARGET = atmega88
#MCU_TARGET = attiny2313
#MCU_TARGET = attiny24
#MCU_TARGET = attiny25
#MCU_TARGET = attiny26
#MCU_TARGET = attiny261
#MCU_TARGET = attiny44
#MCU_TARGET = attiny45
#MCU_TARGET = attiny461
#MCU_TARGET = attiny84
#MCU_TARGET = attiny85
#MCU_TARGET = attiny861
OPTIMIZE = -O2
DEFS =
LIBS =
# You should not have to change anything below here.
CC = avr-gcc
# Override is only needed by avr-lib build system.
override CFLAGS = -g -Wall $(OPTIMIZE) -mmcu=$(MCU_TARGET) $(DEFS)
override LDFLAGS = -Wl,-Map,$(PRG).map
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
all: $(PRG).elf lst text eeprom
$(PRG).elf: $(OBJ)
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
# dependency:
demo.o: demo.c iocompat.h
clean:
rm -rf *.o $(PRG).elf *.eps *.png *.pdf *.bak
rm -rf *.lst *.map $(EXTRA_CLEAN_FILES)
lst: $(PRG).lst
%.lst: %.elf
$(OBJDUMP) -h -S $< > $@
# Rules for building the .text rom images
text: hex bin srec
hex: $(PRG).hex
bin: $(PRG).bin
srec: $(PRG).srec
%.hex: %.elf
$(OBJCOPY) -j .text -j .data -O ihex $< $@
%.srec: %.elf
$(OBJCOPY) -j .text -j .data -O srec $< $@
%.bin: %.elf
$(OBJCOPY) -j .text -j .data -O binary $< $@
# Rules for building the .eeprom rom images
eeprom: ehex ebin esrec
ehex: $(PRG)_eeprom.hex
ebin: $(PRG)_eeprom.bin
esrec: $(PRG)_eeprom.srec
%_eeprom.hex: %.elf
$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O ihex $< $@ || { echo empty $@ not generated; exit 0; }
%_eeprom.srec: %.elf
$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O srec $< $@ || { echo empty $@ not generated; exit 0; }
%_eeprom.bin: %.elf
$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O binary $< $@ || { echo empty $@ not generated; exit 0; }
# Every thing below here is used by avr-libc's build system and can be ignored
# by the casual user.
FIG2DEV = fig2dev
EXTRA_CLEAN_FILES = *.hex *.bin *.srec
dox: eps png pdf
eps: $(PRG).eps
png: $(PRG).png
pdf: $(PRG).pdf
%.eps: %.fig
$(FIG2DEV) -L eps $< $@
%.pdf: %.fig
$(FIG2DEV) -L pdf $< $@
%.png: %.fig
$(FIG2DEV) -L png $< $@
Reference to the source code
Author
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