[lm-sensors] Linking Problem

[lm-sensors] Linking Problem

[Gearoid Murphy]

Hi all,
    This should be trivial for everyone here. I'm trying to write a user 
space program i2c device driver. I access the device using /dev but when 
I try to use functions included in the i2c-core my compiler tells me its 
getting an undefined reference. I know this is because I'm not including 
the proper libraries. How do i get around this?. I've tried explicitly 
including the i2c-core.ko in the gcc compile command but this spews out 
errors about other undefined references.
    All I want to do is successfully communicate to an SRF08 sonar using 
the i2c parallel port adapter for the ELV adapter (built using the 
schema in the i2c docs). I'm using debian 2.6+ and am completely at my 
wits end.
    Any help would be brillant.
    Regards,
    Gearoid

[lm-sensors] Linking Problem

[Mark M. Hoffman]

Hello Gearoid:

* Gearoid Murphy <gearoid.murphy@ul.ie> [2005-06-09 19:54:36 +0100]:
> Hi all,
>    This should be trivial for everyone here. I'm trying to write a user 
> space program i2c device driver. I access the device using /dev but when 
> I try to use functions included in the i2c-core my compiler tells me its 

The functions in i2c-core are for the use of in-kernel drivers (including
kernel modules).  Userspace cannot use them directly.

> getting an undefined reference. I know this is because I'm not including 
> the proper libraries. How do i get around this?. I've tried explicitly 
> including the i2c-core.ko in the gcc compile command but this spews out 
> errors about other undefined references.

Err... no way that could be expected to work.  You can't just link an
object or fragment of the kernel with a user program.

>    All I want to do is successfully communicate to an SRF08 sonar using 
> the i2c parallel port adapter for the ELV adapter (built using the 
> schema in the i2c docs). I'm using debian 2.6+ and am completely at my 
> wits end.

Get the lm_sensors2 package.  Install just the userspace part of it.
That will give you, among other things, /usr/local/include/linux/i2c-dev.h.
Use that in your user program (#include <linux/i2c-dev.h>).  All the
code in that header is inline, so you won't need to link anything else.
The functions are similar to those in i2c-core.

OR, if you're familiar with Python, I wrote a set of Python bindings
for I2C/SMBus access.  You can find them here:

http://members.dca.net/mhoffman/sensors/python/20050122/

Copy those two files somewhere, then 'python ./setup.py --help-commands'.
(I really should include a readme.txt)

Feel free to ask more questions; good luck with your project.

Regards,

-- 
Mark M. Hoffman
mhoffman@lightlink.com