Question

I am new to atmega8. I convert some old freesacle code into atmega8. but seems my chip can not hold code more than 2400 bytes? below is result, when code is 2412 bytes… all things become mess.

code below avrdude is comes from “cat /dev/ttyUSB0”. my debug informations.

avrdude: verifying ...
avrdude: 2412 bytes of flash verified
avrdude: safemode: Fuses OK
avrdude done.  Thank you.

55432111001-0000 6Gn�H(�h�X0443234554321190 6Gn�H        (�h�X0443234554321100-FD-90-6F55432111001-0000 6Gn�H    (�h�X0443234554321190 6Gn�H(�h�X0443234554321100-FD-90-6F^C

but if i reduced code(only audio data), i got right result.

avrdude: verifying ...
avrdude: 2312 bytes of flash verified
avrdude: safemode: Fuses OK
avrdude done.  Thank you.

AVR-IrDA-Tone-Audio start.
version 1.2
--IrDA--    Bin: 1001-0000      Hex: 90     Complete Hex: 00-FD-90-6F

all hfuse, lfuse, lock bits are original value. my code might be 6k with some audio data.

if it is due to boot flash section?

Addtion: ————————————————————————————————–

I change crystal to 8M now.

● ll h8-*
-rw-rw-r-- 1 eexp eexp 933  9月 22 00:27 h8-reduce.c
-rw-rw-r-- 1 eexp eexp 14K  9月 22 00:26 h8-org.c

● cp h8-org.c h8.c

● avr.sh main.c
......
avrdude: 5272 bytes of flash verified

now all goes mess.

● cp h8-reduce.c h8.c

● avr.sh main.c
.....
avrdude: 1872 bytes of flash verified

now all goes right, but i lost almost all audio data.

below is h8.c.

● head h8.c
const unsigned char h8[] =
{
    36,14,0,0,129,129,128,129,130,127,126,128,128,127,128,130,131,128,127,127,127,126,127,129,130,130,129,129,128,128,128,128,128,126,126,129,128,127,127,130,133,130,126,126,129,128,125,127,128,129,128,127,129,128,127,127,127,128,128,129,127,127,129,128,130,130,128,128,127,126,128,128,128,130,129,128,129,126,126,125,127,132,130,127,126,129,131,127,127,133,133,127,122,125,129,130,127,127,130,129,
    126,125,127,128,129,128,128,128,128,127,127,129,128,129,129,128,126,127,129,127,128,127,128,130,129,129,128,128,127,127,129,130,128,128,129,129,127,127,128,128,128,128,128,128,126,126,129,129,127,129,130,130,126,126,128,128,127,128,131,130,127,126,126,128,129,125,128,130,131,128,126,129,128,129,125,126,130,129,131,130,131,129,125,128,129,131,130,127,130,129,127,128,127,129,128,126,126,127,128,126,
    127,127,128,128,128,127,127,127,127,127,129,128,129,128,128,129,129,128,128,129,128,128,128,129,0xff,
};

Answer 1

i guess you are loading the audio data into the ram. a variable declaration like

  char* data = "somerandomdata"; 

is putting all the data in the SRAM, and you just have 1kbyte of SRAM in the mega8 (which also contains the stack etc).

if the lock bits are in their original state, the bootloader mechanism should not cause this error.

you should specify the audio data as program space, here is the description how:

Avr LibC PGM Space

here is how your code should look like:
h4.c

       #include <avr/pgmspace.h>

       const unsigned char h4[] PROGMEM = { 18,7,0,0,128,128,128,127,127,129,129,127,126,128,130,129,128,129,127,127,128,12‌​8,132,127,129,126,128,128,127,127,127,129,127,127,130,129,127,127,129,130,129,125‌​,

you need to adjust your set_audio function,
every reading of the pointer h4 shall be done in this way:
change for example

  value = *h4_copy++;

to

  value = pgm_read_byte(h4_copy); h4_copy++;