This tutorial will walk you through the process of writing and compiling an application with NuttX. The tutorial will focus on the method and hence I "borrowed" some materials from sdharrison. At the end of the tutorial, you will notice that our project is pretty similar to other apps in the apps/examples folder.

1. Prepare necessary files

mkdir -p apps/examples/my_app
cd apps/examples/my_app
touch Kconfig Make.defs counter.c Makefile
nano *

Just in case you are wondering:

touch is a command to create files, so we created a series of files with names that followed

nano * is to edit all the files in the current directory

Here comes the content of those files

primes.c

#include <nuttx/config.h>
#include <stdio.h>
#include <time.h>

static double TimeSpecToSeconds(struct timespec* ts){
    return (double)ts -> tv_sec + (double)ts->tv_sec / 1000000000.0;
}

#ifdef CONFIG_BUILD_KERNEL
int main (int argc, FAR char *argv[])
#else
int counter_main(int argc, char *argv[])
#endif
{
    struct timespec start;
    struct timespec end;
    double elapsed_secs;

    int N = 1000;
    int i = 1;

    printf("Hello world! I am good at counting! Here I go... \n");
    clock_gettime(CLOCK_MONOTONIC, &start);

    while (i <= N) {
            printf("%d ", i);
            i = i + 1;
    }
    clock_gettime(CLOCK_MONOTONIC, &end);
    elapsed_secs = TimeSpecToSeconds(&end) - TimeSpecToSeconds(&start);
    printf("\n See... I counted &d numbers in %.3f seconds", N, elapsed_secs);

    return 0;
}

Kconfig

config EXAMPLES_MY_APP
bool "MY FIRST APP - COUNTING"
default n
---help---
Enable the \"Counter\" Example
if EXAMPLES_MY_APP
endif

Make.defs

ifeq ($(CONFIG_EXAMPLES_MY_APP), y)
CONFIGURED_APPS += examples/my_app
endif

Makefile

-include $(TOPDIR)/Make.defs

APPNAME = counter
PRIORITY = SCHED_PRIORITY_DEFAULT
STACKSIZE = 2048

ASRCS =
CSRCS =
MAINSRC = counter.c

CONFIG_MY_APP_PROGNAME ?= counter$(EXEEXT)
PROGNAME = $(CONFIG_MY_APP_PROGNAME)

include $(APPDIR)/Application.mk

apps/examples/Kconfig Insert the following line (apps arranged alphabetically)

source "$APPSDIR/examples/my_app/Kconfig"

File editing is complete. Now go back into the nuttx directory and prepare for compliation

2. Compilation

cd nuttx/

make apps_distclean
make menuconfig

• Application Configuration --->
  • Examples --->
    • Select [*] MY FIRST APP - COUNTING
    • Exit
  • Exit
• RTOS Features -->
  • Tasks and Scheduling --->
    • Application entry point
      • Type: counter_main
      • Exit
    • Exit
  • Clocks and Timers --->
    • Select [*] Support CLOCK_MONOTONIC
    • Exit
  • Exit
• Exit & Save

make

If everything compiles without error, then you should have three output files

• nuttx (Arm Elf 32 Bit Executable)
• nuttx.bin (binary data file)
• nuttx.hex (Ascii file)

The 'nm' command recognizes the nuttx Arm Elf file and will list the symbols. Use as follows:

nm nuttx | grep primes_main

you should see something like this: 080047a5 T primes_main

3. Reference

http://sdharrison.blogspot.sg/?view=classic