Passing variables when compiling/building project

[ns_esp]

Hello,
I'd like to be able to pass variables into my code when building a project, so that parameters such as IP address, device name, and password can be changed without editing my code.
I know that in C there is the compiler flag -D that can do this, but I'm not sure how to use it in the esp idf.py build.
To attempt this I modified the blink.c example to print out the integer passed through the compiler/

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/* Blink Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "sdkconfig.h"

#define BLINK_GPIO CONFIG_BLINK_GPIO

void app_main()
{
    gpio_pad_select_gpio(BLINK_GPIO);
    /* Set the GPIO as a push/pull output */
    gpio_set_direction(BLINK_GPIO, GPIO_MODE_OUTPUT);
    while(1) {
        /* Blink off (output low) */
	printf("Turning off the LED\n");
        gpio_set_level(BLINK_GPIO, 0);
        vTaskDelay(1000 / portTICK_PERIOD_MS);
        /* Blink on (output high) */
	printf("Turning on the LED\n");
        gpio_set_level(BLINK_GPIO, 1);
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    printf("%i\n",test);
    }
}

I then called:
idf.py build -Dtest=1

I received the warning when compiling:

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CMake Warning:
  Manually-specified variables were not used by the project:

    test

But the compile failed since:

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../main/blink.c: In function 'app_main':
../main/blink.c:48:19: error: 'test' undeclared (first use in this function)
     printf("%i\n",test);
                   ^~~~
../main/blink.c:48:19: note: each undeclared identifier is reported only once for each function it appears in

Is there something I am missing? Any advice would be appreciated.

Thank you very much!

[CatalinM]

I know it's been 4 years, but I was looking for something like this and I couldn't find any solution on the internet.

However, I did find a way to get this going, so I want to post an answer for anyone else looking for a similar solution.

In you main `CMakeLists.txt` file, you need to define the option you want to pass from command line, like so:

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option(DEV_MODE "Enable Project development mode" 0)

Then, in your sources `CMakeLists.txt`, you can check for that option and pass a flag into your code:

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if(DEV_MODE)
        target_compile_definitions(${COMPONENT_TARGET} PUBLIC "-DDEVELOPMENT_MODE")
endif()

[nopnop2002]

I'd like to be able to pass variables into my code when building a project, so that parameters such as IP address, device name, and password can be changed without editing my code.

For this purpose, use Kconfig.projbuild.

https://github.com/espressif/esp-idf/bl ... .projbuild

[MicroController]

The canonical way in IDF is via Kconfig: https://docs.espressif.com/projects/esp ... guide.html

[nopnop2002]

There is also a method like this.

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# The following lines of boilerplate have to be in your project's
# CMakeLists in this exact order for cmake to work correctly
cmake_minimum_required(VERSION 3.5)


include($ENV{IDF_PATH}/tools/cmake/project.cmake)
project(version)

idf_build_set_property(COMPILE_OPTIONS "-DOPTION_INT=10" APPEND)
idf_build_set_property(COMPILE_OPTIONS "-DOPTION_HEX=0x10" APPEND)
idf_build_set_property(COMPILE_OPTIONS "-DOPTION_FLOAT=12.3" APPEND)
idf_build_set_property(COMPILE_OPTIONS "-DOPTION_STR=abcdefg" APPEND)

You can get this option value.

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#include <stdio.h>

#define TO_STR(x) #x
#define TO_STR_WRAPPER(x) TO_STR(x)

void app_main()
{
    printf("app_main\n");
#ifdef OPTION_INT
    printf("OPTION_INT=%d\n", OPTION_INT);
#endif
#ifdef OPTION_HEX
    printf("OPTION_HEX=0x%x\n", OPTION_HEX);
#endif
#ifdef OPTION_FLOAT
    printf("OPTION_FLOAT=%f\n", OPTION_FLOAT);
#endif
#ifdef OPTION_STR
    printf("OPTION_STR=[%s]\n", TO_STR_WRAPPER(OPTION_STR));
#endif
}

idf.py build

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I (284) main_task: Started on CPU0
I (294) main_task: Calling app_main()
app_main
OPTION_INT=10
OPTION_HEX=0x10
OPTION_FLOAT=12.300000
OPTION_STR=[abcdefg]
I (294) main_task: Returned from app_main()

[ESP_igrr]

so that parameters such as IP address, device name, and password can be changed without editing my code.

And yet another option, if you want to avoid even rebuilding the app when these variables change, you can use a component I wrote:
https://components.espressif.com/compon ... vs-dotenv/

With it, you can put the variables into a .env file in your project directory. The content of .env will be converted into an NVS partition binary at build time, which will be uploaded to the device along with your application. In the application you can then call the standard getenv function to read these values.

[CatalinM]

The canonical way in IDF is via Kconfig: https://docs.espressif.com/projects/esp ... guide.html

It is and it works great for settings that rarely change, but my use case was slightly different - I want to start the ESP without WiFi in "production" and only turn it on when receiving a hardware signal. However, when developing I always want WiFi on so I can test stuff. It's easier to config this from the CLI when I run `idf.py build flash monitor` instead of going to Kconfig to change settings.

[MicroController]

I want to ... in "production" [...] However, when developing I always want ...

You may want to check out Cmake Build Configurations.