Problems with attachInterrupt while in C

Forum 2005-2010 (read only) Software Development
1

Hi.

I have been playing with the Arduino board I got for xmas and I hit a little problem while using attachInterrupt in C.

If I rewrite the code in the Arduino IDE then attachInterrupt works so it's not a wiring problem. For various reasons I have been playing in old fashion C and want this to work there. :slight_smile:

Is there some trick to this? Is there something really really obvious I am missing?

You can check out my code here: my-arduino-code/ledarray-v2.c at master · JonGretar/my-arduino-code · GitHub

2

Hi Jon,

It might be easier to diagnose if you would explain what your "little problem" is. Compiler error? Malfunction? Unexpected behavior?

Mikal

3

Hehe... sorry.. My bad.

The interrupt function never runs in the C code. Thus it never changes change_state to HIGH on trigger.

Everything compiles and uploads fine. The loop runs fine. Running got_interrupt() manually works. Just does nothing when I activate the interrupt trigger.

4

If you rename the file to .cpp and compile it exactly as-is with the C++ compiler, does it still not work?

5

Same thing. Program upload. Runs fine.. Just no interrupts. I have the new Duemilanove if that matters.

=> [avr-gcc] ledarray-v2.elf
avr-gcc -mmcu=atmega168 -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -I. -gstabs -DF_CPU=16000000 -Os -Wall -Wstrict-prototypes -std=gnu99 -I/Applications/Electronics/arduino-0012/hardware/cores/arduino -o ledarray-v2.elf ledarray-v2.c  -L. core.a -lm

 => [avr-objcopy] ledarray-v2.hex
avr-objcopy -O ihex -R .eeprom ledarray-v2.elf ledarray-v2.hex

 => [avrdude] ledarray-v2.hex
avrdude -p atmega168 -P /dev/tty.usbserial-A60061eR -C /Applications/Electronics/arduino-0012/hardware/tools/avr/etc/avrdude.conf -c stk500v1 -b 19200 -F -u -U flash:w:ledarray-v2.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude: Device signature = 0x000000
avrdude: Yikes!  Invalid device signature.
avrdude: Expected signature for ATMEGA168 is 1E 94 06
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "ledarray-v2.hex"
avrdude: input file ledarray-v2.hex auto detected as Intel Hex
avrdude: writing flash (3164 bytes):

Writing | ################################################## | 100% 2.59s

avrdude: 3164 bytes of flash written
avrdude: verifying flash memory against ledarray-v2.hex:
avrdude: load data flash data from input file ledarray-v2.hex:
avrdude: input file ledarray-v2.hex auto detected as Intel Hex
avrdude: input file ledarray-v2.hex contains 3164 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 2.38s

avrdude: verifying ...
avrdude: 3164 bytes of flash verified

avrdude done.  Thank you.
6

If you're playing around in straight up C, you should ditch attachInterrupt and write your own interrupt handlers in the avr-libc syntax.

7

Okz. Thanks. I'll dig into the interrupts manually.

Just so I know. Is there some reason for this? attachInterrupt seems to be a C function.

8

Jon, it occurred to me last night as I was going to sleep that attachInterrupt probably has some dependency on the Arduino initialization sequence. Try simply adding

init();

to the top of your main() function.

Mikal

9

Ahh... That did the trick. :slight_smile:

Thanks. Didn't know about init();