View source for Building simple C program for VisionSOM-STM32MP1

{{PageHeader|Building simple C program for VisionSOM-STM32MP1}} __toc__

This article describes how to build a simple Hello World C application fo the VisionSOM-STM32MP1 module. To do this we need to have the installed toolchain as described in the article [[OpenSTLinux for VisionSOM-STM32MP1]]. In this example the toolchain is installed in the ''/opt/st/stm32mp157a-visionsom-mx/2.6-snapshot'' directory.

= Configuring the environment =

The environment configuration script is installed with the toolchain. We need to call it in order to configure required environmental variables:

<pre>
. /opt/st/stm32mp157a-visionsom-mx/2.6-snapshot/environment-setup-cortexa7t2hf-neon-vfpv4-openstlinux_weston-linux-gnueabi
</pre>

We can verify it by checking the value of the CC variable:

<pre>
echo $CC
</pre>

the example output looks like this:

<pre>
arm-openstlinux_weston-linux-gnueabi-gcc -march=armv7ve -mthumb -mfpu=neon-vfpv4 -mfloat-abi=hard -mcpu=cortex-a7 --sysroot=/opt/st/stm32mp157a-visionsom-mx/2.6-snapshot/sysroots/cortexa7t2hf-neon-vfpv4-openstlinux_weston-linux-gnuea
</pre>

This configuration step has to be repeated in each terminal separatelly every time after opening it.

= Building the example code =

Now we can create a simple program in the HelloWorld.c file: 

<pre>
#include <stdio.h>

int main() {
	printf("Hello world!\n");
	return 0;
}
</pre>

and compile it using the previously prepared terminal:

<pre>
$CC -o HelloWorld HelloWorld.c
</pre>

The created executable can be run only on ARM architecture - it can be verified by calling the command:

<pre>
file HelloWorld
</pre>

The output contains the details about the binary:

<pre>
HelloWorld: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-, for GNU/Linux 3.2.0, BuildID[sha1]=0ba619f33a20c2521f445510df799064aa330e2f, with debug_info, not stripped
</pre>

Now it is time to upload the executable file to the target using ssh or by copying it directly to the SD card and running it from the target terminal:

<pre>
root@stm32mp157a-visionsom-mx:~# ./HelloWorld 
Hello world!
</pre>