Hello Community,

I'm using Atmel Studio 6.2 and Visual Micro. I want to mix Assembler with C++ using a .S-file.
Unfortunately I have a linker problem, the output of the compiler run creates an undefined reference to `foobar' error.

Following tips from the internet I created a .S file containing a function pulling some port pins:

 #include <avr/io.h>

 .section .text
 .global foobar
  foobar:

 start:
	cbi		0x05,4
	sbi		0x05,4

	sbi		0x05,5
	sbi		0x05,3
	nop
	cbi		0x05,5
	cbi		0x05,3
	rjmp	start 

My .ino - file contains the declaration line

extern "C" {void foobar(void);} 

and in the setup() function I call my function

	foobar(); 

 

However, when I try to compile the outcome is 

Compiling 'LCD7SEG' for 'Arduino Uno'
LCD7SEG.cpp.o:In function `setup'
LCD7SEG.ino:undefined reference to `foobar'
Error creating .elf 

I tried to put the assembler source code in the sketchbook\libraries subfolder, in the folder where the ino file lives, I added it as a library or just as a source code to the solution explorer - it does not work.

To me it looks like the system just not assembles the source code - how can I make that happen (and tell the linker to use the .O file)?

Thank you very much

Hi, 

it works picture perfect with the Arduino IDE, just triple checked it.

Cheers

Thanks for the files which show that Visual Micro is unable to find or detect the Send595 library.

LCD7SEG.ino:29:21: warning: Send595.h: No such file or directory

Questions

Can you see the Send595 library on menu "project>add/import sketch library>user"?

Are you using the visual micro version from the atmel gallery? you can see tools>options>visual micro>version if you are not sure. The current version on visual micro is a little more recent and will show 1407.10 and minor version 10

If you are not on the latest visual micro release then please close atmel studio and run the visual micro installer from visualmicro.com

If you are on the latest release and the issue remains then please switch on "tools>options>visual micro>user interface>trace". Then restart atmel studio and email the trace that appears in the output window.

Thanks again

Hi,

Thanks for the trace which looks okay.

Yes it is an interesting problem. 

Can you please zip and email your library folder called Serial595 and also your sketch code. The codes will be kept private and deleted after the test.

Thanks

Hi,

Thanks for the update. Some extra info that might help

To include an arduino library in a sketch the header files of the library must be #include "header.h" in the main sketch code. This is what the Visual Micro "project>add/import sketch library does"

A library must be included in the main sketch if it is used in any cpp files of the sketch.

.............

It was good that you report this. Although assembler was being correctly compiled with Visual Micro and Arduino 1.0.x it failed with Arduino 1.5.x. That is fixed for the next release but does not affect you.

I wasn't aware that the Arduino build process does not support assembler in the sketch code. I am not sure if that is intentional or not so will investigate what should or should not happen to sketch source codes.

thanks again