On Tue, Apr 23, 2013 at 12:36:30PM -0700, Eastman Hackney wrote:
>
>
> I'm stumped & some help would be GREATLY appreciated. Weening myself from
> Windows and AVR Studio (after realizing that it uses avr-gcc!). I apologize if
> this posting is verbose - but I wanted to be thorough.
>
>
> Using avr-gcc version 4.3.4 (obtained with 'apt-get install gcc-avr avr-libc
> avrdude' ...).
>
>
> Compiling and linking with commands copied from the avr-libc user manual:
>
> avr-gcc -c -gstabs -g -O0 -mmcu=avr5 -mmcu=atmega644p main.c
> avr-gcc -mmcu=avr5 -mmcu=atmega644pa -o main.elf main.o -lm
> avr-objdump -D -h -S main.elf > main.lst
> avr-gcc -g -mmcu=avr5 -mmcu=atmega644pa -Wl,-Map,main.map -o main.elf main.o
> avr-objcopy -j .text -j .data -O ihex main.elf main.hex
> sudo avrdude -P usb -p m644 -c jtagmkII -e -U flash:w:main.hex:a
Can you drop the -mmcu=avr5 and try? I don't have a copy of 4.3.4 right
now, but atleast the last few versions of the compiler (avr-gcc 4.6.2
and above) know what arch the mcu belongs to, and the driver
automatically passes that on to the assembler/linker - you don't have to
specify that explicitly.
On the latest toolchain, I see the correct behavior if I drop the
mmcu=avr5 i.e. > 20 entries in the vector table, and the behavior you
describe if the option is present.
Explicitly specifying -mmcu=avr5 when linking results in the following command
line to the linker.
/home/saaadhu/avr/install/libexec/gcc/avr/4.9.0/collect2 -m avr5
/home/saaadhu/avr/install/lib/gcc/avr/4.9.0/../../../../avr/lib/avr5/crtm16.o
-L/home/saaadhu/avr/install/lib/gcc/avr/4.9.0/avr5
-L/home/saaadhu/avr/install/lib/gcc/avr/4.9.0/../../../../avr/lib/avr5
-L/home/saaadhu/avr/install/lib/gcc/avr/4.9.0
-L/home/saaadhu/avr/install/lib/gcc/avr/4.9.0/../../../../avr/lib
/tmp/ccCrT1hV.o --start-group -lgcc -lm -lc --end-group
Notice that it is linking against crtm16.o, which I guess is the
"canonical" avr5 device according to libc, and the vector table is of
course for that device.
If you still see the same behavior after removing -mmcu=avr5 (atleast
when linking), can you add -v and -Wl,--verbose and show us the output?
Regards
Senthil
>
> When flash is loaded, the code runs fine, including a Timer0 ISR. But if I
> enable the UART1
> TXCIE1 interrupt flag (Atmega644 has two Uarts), the USART1_UDRE_vect does
> not seem
>
> to show up in the interrupt Vector Table.
>
>
> Looking at the compiler-generated code in main.lst shows only 21 vectors
> (Atmega644 datasheet
> lists 31 vectors), and does not include a vector for USART1_UDRE_vect. The
> listed vectors seem
>
> correct for the Atmega644, but why won't it include vectors greater than
> vector_20, and specifically
> the one for USART1_UDRE_vect?
>
> Listing of main.lst:
>
> Disassembly of section .text:
>
> 00000000 <__vectors>:
> 0: 0c 94 2a 00 jmp 0x54 ; 0x54 <__ctors_end>
> 4: 0c 94 60 03 jmp 0x6c0 ; 0x6c0 <__vector_1>
> 8: 0c 94 61 03 jmp 0x6c2 ; 0x6c2 <__vector_2>
> c: 0c 94 62 03 jmp 0x6c4 ; 0x6c4 <__vector_3>
> 10: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 14: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 18: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 1c: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 20: 0c 94 63 03 jmp 0x6c6 ; 0x6c6 <__vector_8>
> 24: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 28: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 2c: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 30: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 34: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 38: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 3c: 0c 94 67 03 jmp 0x6ce ; 0x6ce <__vector_15>
> 40: 0c 94 7e 02 jmp 0x4fc ; 0x4fc <__vector_16>
> 44: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 48: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 4c: 0c 94 47 00 jmp 0x8e ; 0x8e <__bad_interrupt>
> 50: 0c 94 64 03 jmp 0x6c8 ; 0x6c8 <__vector_20>
>
> 00000054 <__ctors_end>:
> 54: 11 24 eor r1, r1
>
> The C source code for the USART1_UDRE_vect is:
>
> ISR(USART1_UDRE_vect, ISR_NAKED)
> {
> uc cSREG;
>
> cSREG = SREG;
> if (U1_tx_count > 0)
> {
> UDR1 = U1_tx_fifo[U1_tx_optr];
> U1_tx_optr++;
> if (U1_tx_optr >= TX_FIFO_SIZ)
> U1_tx_optr = 0;
> U1_tx_count--;
> }
> else
> UCSR1B &= ~(1 << UDRIE1);
> SREG = cSREG;
> reti();
> }
>
>
> Thanks for considering this. East Hackney
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