How to install gcc

[Kit Bishop]

@Justin-Sowers @Boken-Lin I have created a new post (https://community.onion.io/topic/533/using-linux-swap-space-on-the-omega) that contains the guide.
Hope it is useful.

[Ahmed Mkadem]

@Kit-Bishop then how can you compile a C program ? can you explain it to me please ?

[Kit Bishop]

@Ahmed-Mkadem I compile C/C++ using cross compilation on a Linux system (I use Kubuntu).
Some details can be found at https://community.onion.io/topic/9/how-to-install-gcc/22

You may also be interested in the set of C++ libraries and programs I have produced for perfroming GPIO, I2C and Arduino access on the Omega. The full set of these can be found at https://github.com/KitBishop/Omega-GPIO-I2C-Arduino The various documentation .pdf files therein give more details.

You might in particular look at the template program that is included in the above referenced package - see https://github.com/KitBishop/Omega-GPIO-I2C-Arduino/tree/master/iotemplate and its documentation at https://github.com/KitBishop/Omega-GPIO-I2C-Arduino/blob/master/iotemplate/iotemplate.pdf

Hope that helps

[Ahmed Mkadem]

@Kit-Bishop Thank you !! this is helpful

[anglo marc]

@Kit-Bishop hi dear
im new with Linux and want to use the cross compiler
can you please explain ho to do these steps !
setting the environment variables , install the tool chain ?
also the omega didn't have sftp server so how can i transfer the executable file ?

[anglo marc]

@Boken-Lin said in How to install gcc:

@Justin-Sowers The Omega (or most OpenWRT devices for that matter) has very limited computational resources, so people don't generally compile anything directly on them, which is probably why you are unable to find packages that allow you to install build tools. However, things like make and autoconf are just binaries that can you compiled from source. So if you want to compile it for the Omega, it's simply a matter of creating a Makefile in your cross-compile environment and build an opkg package out of them.

hi dear
is there ant tutorial explain that process in actual details ?

[José Luis Cánovas]

@anglo-marc you can start from here.

[Przemyslaw Downar]

hello i install gcc. I downloaded library i2c from https://github.com/OnionIoT/i2c-exp-driver

• onion-i2c.c

• onion-i2c.h

• onion-debug.c

• onion-debug.h

wrote a program, copy files to usr/c/ and run gcc

gcc  -I usr/c/ -o program usr/c/HTU21D.c

but while compiling gets an error:

/tmp/ccnKdEjA.o: In function `getTemperature()':
HTU21D.c:(.text+0x88): undefined reference to `i2c_writeBytes'
HTU21D.c:(.text+0x94): undefined reference to `i2c_writeBytes'
collect2: error: ld returned 1 exit status

my program:

#include "HTU21D.h"
int main ()
{
    printf("Hello world!\n ");
    //printf("%5.2fC\n", getTemperature());
    return 0;
}
double getTemperature()
{
unsigned char buf [32];
int     status;
 i2c_writeBytes(0, 0x80, 0xF3, 0, 0);
//status = i2c_read(0, HTU21D_I2C_ADDR, HTU21D_TEMP, buf, 3);

unsigned int temp = (buf [0] << 8 | buf [1]) & 0xFFFC;

double tSensorTemp = temp / 65536.0;
return -46.85 + (175.72 * tSensorTemp);
}

file .h

#ifndef _HTU21D_H_
#define _HTU21D_H_

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <onion-i2c.h>
#define   HTU21D_I2C_ADDR 0x80

#define   HTU21D_TEMP     0xF3
#define   HTU21D_HUMID    0xF5
double getTemperature();
#endif

[José Luis Cánovas]

@Przemyslaw-Downar

• Your file.h should be named HTU21D.h.
• Delete the space after the -I argument.
• Move every unnecessary #include from the .h to the c/ cpp file. In this case, all.

[Chris Stratton]

None of those suggestions are likely to help. Unless there are missing macro definitions, an "undefined reference" error is an issue with linking rather than compilation.

You need to be passing whatever implements this function to the linker, either as a library or as an additional object file, or by providing it to the compiler as an additional source file to be built.

[Przemyslaw Downar]

@Chris-Stratton Thanks Very Much, it works: D

gcc   -Iusr/c/ -o simpleprg usr/c/HTU21D.c usr/c/onion-i2c.c usr/c/onion-debug.c

[anglo marc]

@Boken-Lin said in How to install gcc:

Hi Ajay,

/tmp is a RAM disk, which means after your do a reboot, it will disappear. You might want to check out the tutorial here that shows you how to mount a USB drive to the Omega: https://onion.freshdesk.com/support/solutions/articles/6000080075-how-can-i-use-usb-storage- Moreover, it's not recommended to install gcc on the Omega. If you want to compile programs for the Omega, it's generally recommended to setup a cross-compile environment on your computer/server to compile for it.

For more information about setting up the cross-compile environment, please take a look at this guide: https://github.com/OnionIoT/OpenWRT-Packages/wiki/Setting-Up-the-Cross-Compile-Environment

Cheers!

hi dear
i see this article .. its not clear for me as beginner in Linux
most of steps i don't know where !
can help please ?

[José Luis Cánovas]

@anglo-marc check my signature for a Docker ready environment, or check this project to setup it in your host pc.