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 Posted: Mar 11, 2010 - 07:27 AM |
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Joined: Feb 24, 2010
Posts: 4
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Hello all,
I spent last night's 5 hours trying to figure out why my array literal is not initializing to the literal values given (nasty words didn't help). All the values are 255 instead it seems.
sample showing off my woes:
code should just blink some lights on PORTB
Code:
#define F_CPU 8000000UL
#include <inttypes.h>
#include <avr/io.h>
#include <util/delay.h>
uint8_t array[] = {42, 86, 125, 220}; //meaningful literals
int main()
{
uint8_t i;
//static uint8_t array[] = {42, 86, 125, 220}; //test 1
//array[0] = 42; array[1] = 86; array[2] = 125; array[3] = 220; //test 2 --hack--
DDRB = 0xff;
while(1)
{
for(i = 4; i--;)
{
_delay_ms(250);
PORTB = array[i]; // =(
//PORTB = i; //test 3
}
}
}
tried:
- putting the array inside and static didn't help
- doing the initializing myself works (but is messy, worse in my real program)
- putting the variable i to the port works, so i haven't broken the leds yet
close to the same problem, but for exmem
Any insight would be awesome.
env:
stk500
atmega8515
winavr 20100110
(avr-gcc -mmcu=atmega8515 -I. -Os -Wall -std=gnu99 main.c)
win7 x64
thanks |
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Posted: Mar 11, 2010 - 08:39 AM |
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Joined: Feb 12, 2005
Posts: 7302
Location: Cratfield, England
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What makes you think that the program does not work?
It simulates perfectly. loading 0xDC, 0x7D, 0x56, 0x2a ... into PORTB.
The STK500 leds are active-low. So 0xDC will light LED0, LED1, LED5.
David. |
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Posted: Mar 11, 2010 - 09:32 AM |
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Joined: Feb 24, 2010
Posts: 4
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In studio it worked for me too. Course this isn't the first time studio didn't match hardware for me; always skeptical now.
I'll have some time to test this program on an atmega16/stk500 today to rules out the 8515, but I can't see any reason for it to be the problem. |
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Posted: Mar 11, 2010 - 10:38 AM |
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Joined: Feb 12, 2005
Posts: 7302
Location: Cratfield, England
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acurseoffear wrote:
In studio it worked for me too. Course this isn't the first time studio didn't match hardware for me; always skeptical now.
Why do you say this?
It is clearly documented that Studio does not simulate a Terminal or TWI etc.
But executing regular AVR instructions, simulating Timers and interrupts should work fine.
You are hardly trying to do anything complicated.
David. |
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Posted: Mar 11, 2010 - 11:30 AM |
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Joined: Jul 23, 2001
Posts: 975
Location: Osnabrueck, Germany
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| Your avr-gcc command line implies that you don't use the Makefile generated by AVR-Studio. Show us how you generate the hex-file. Uninitialized global variables are normally the result of not adding the .data section to the hex-file. |
_________________
Stefan Ernst
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Posted: Mar 12, 2010 - 04:11 AM |
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Joined: Feb 24, 2010
Posts: 4
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Thanks for mentioning the make rules. Hadn't looked at that yet. I got it working changing the first objcopy to:
Code:
$(OBJCOPY) -O $(FORMAT) -j .text -j .bss -j .data $< $@
what was run:
Code:
avr-gcc -c -mmcu=atmega8515 -I. -Os -Wall -std=gnu99 main.c -o main.o
avr-gcc -mmcu=atmega8515 -I. -Os -Wall -std=gnu99 main.o --output main.elf
avr-objcopy -O ihex -j .text main.elf main.hex
avr-objcopy -j .eeprom --set-section-flags=.eeprom="alloc,load" \
--change-section-lma .eeprom=0 -O ihex main.elf main.eep
Thanks a lot for the tip. Also good eyes. |
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Posted: Mar 12, 2010 - 08:36 AM |
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Joined: Jul 23, 2001
Posts: 975
Location: Osnabrueck, Germany
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| There is no need for the "-j .bss". |
_________________
Stefan Ernst
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Posted: Mar 12, 2010 - 09:46 AM |
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Joined: Jul 18, 2005
Posts: 33138
Location: (using avr-gcc in) Finchingfield, Essex, England
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| If you want to use your own Makefile then why not use Mfile? - the template has had a LOT of thought put into it and you won't be caught by silly mistakes like this. |
_________________
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Posted: Mar 12, 2010 - 07:19 PM |
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Joined: Feb 24, 2010
Posts: 4
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| Didn't know that existed. Now that I'm looking at it and mine; it looks like mine was based on mfile some time in its past. Thanks for the tip. |
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