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How to parse and read JSON file correctly?

Hi guys,

I am using the nRF52832 board and I want to parse and read my JSON file. I don't have too much experience working with cJSON and here you will find my simple code where I try to understand how to define things properly. I will appreciate a lot if you can help me with some advice or better if you can suggest me where I made errors.

Best regards,

Adnan.

/*
 * Copyright (c) 2012-2014 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <sys/printk.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <float.h>
#include <limits.h>
#include <ctype.h>
#include "cJSON.h"


char *create_hello(void) {
	
	char *string;
	
	cJSON *hello = cJSON_CreateObject();
	
	cJSON *functionName = cJSON_CreateString("hello_world");
	cJSON_AddItemToObject(hello, "functionName", functionName);
	
	string = cJSON_Print(hello);
	
	cJSON_Delete(hello);
	return string;
	
	}

void hello_world (void) {
	
	printk("Hello World! %s\n", CONFIG_BOARD);
	}


void main(void)
{
	const char *hello = "{\"functionName\": \"hello_world\"}";
	cJSON *hello_json = cJSON_Parse(hello);
	cJSON *functionName = cJSON_GetObjectItemCaseSensitive(hello_json, "functionName");
	
	while(true){
		
		if (functionName == "hello_world") {
			hello_world();
			k_sleep(K_SECONDS(1));
			}		
			
		}
}

Parents
  • Hello, Aduka!

    Thank you for reaching out. First of all, have you defined the correct prj.conf for your application? Mine looks like this for the hello_world sample:

    # nothing here
    CONFIG_CJSON_LIB=y
    
    # newlibc
    CONFIG_NEWLIB_LIBC=y

    Secondly, your code is mostly correct, but you have done an illegal comparison in your while loop. Look at my main below, where the error is corrected:

    void main(void)
    {
    	const char *hello = "{\"functionName\": \"hello_world\"}";
    	cJSON *hello_json = cJSON_Parse(hello);
    	char* functionName = cJSON_Print(cJSON_GetObjectItemCaseSensitive(hello_json, "functionName"));
    	
    	while(true){
    		
    		if (strcmp(functionName, "hello_world")) {
    			hello_world();
    			k_sleep(K_SECONDS(1));
    			}		
    			
    		}
    }

    In the code above I have changed line 45 so that cJSON_Print is used to write the content to a string. Then I have changed 49 to use strcmp, for comparing the strings. The line numbers I reference are from your original code. 

    Hope this helps you on your way, and please reach out if you wonder about anything else. 

    Best regards,
    Carl Richard

  • Hi Carl,

    Thanks a lot for this help and suggestions! I tried this code with these corrections, but again I am not able to compile it on my board. Now the problem occurs in my proj.conf file I think.

    This is the error:

    error: Aborting due to Kconfig warnings

    CMake Error at /home/adnan/zephyrproject/zephyr/cmake/kconfig.cmake:217 (message):
    command failed with return code: 1
    Call Stack (most recent call first):
    /home/adnan/zephyrproject/zephyr/cmake/app/boilerplate.cmake:510 (include)
    /home/adnan/zephyrproject/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:24 (include)
    /home/adnan/zephyrproject/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:40 (include_boilerplate)
    CMakeLists.txt:5 (find_package)


    -- Configuring incomplete, errors occurred!
    See also "/home/adnan/zephyrproject/zephyr/build/CMakeFiles/CMakeOutput.log".
    See also "/home/adnan/zephyrproject/zephyr/build/CMakeFiles/CMakeError.log".
    FAILED: build.ninja
    /usr/bin/cmake --regenerate-during-build -S/home/adnan/zephyrproject/zephyr/samples/hello_world_cjson -B/home/adnan/zephyrproject/zephyr/build
    ninja: error: rebuilding 'build.ninja': subcommand failed
    FATAL ERROR: command exited with status 1: /usr/bin/cmake --build /home/adnan/zephyrproject/zephyr/build

    Can you maybe figure out what could be a potential problem now? And also, I forgot to tell that I use Zephyr if that is important for this problem. Also, my last question is related to Makefile and prj.conf files...where I can find the proper configuration for different samples. For sure, I will need to use cJSON together with my BLE example.

    Thanks in advance and best regards,

    Adnan.

  • Hi again!

    In Ubuntu it should be enough to call "unset ZEPHYR_BASE" on the command line and restarting your shell. And yes, gnuarmemb is just an empty directory and it does not need to be in the NCS directory. We recommend the location "~/gnuarmemb".

    I understand you. It's a bit convoluted.

    Best regards,
    Carl Richard

  • Hi Carl,

    I tried to unset this variable, but there is still the same error when I try to run this command:

    west init -m github.com/.../sdk-nrf --mr v1.3.2

    Error:

    FATAL ERROR: already initialized in /home/adnan, aborting.

    Now I only see the chance to reboot the whole Ubuntu and start from scratch everything. Do you see
    any possible solution of this error?

    Best regards,

    Adnan.
  • Hi again!

    Can you try to call:

     

    env | grep ZEPHYR_BASE

    and write the output here? 

    Could you also try the following steps:
    1. Uninstall west from your system (pip uninstall west)
    2. Find any folder named .west and delete it
    3. Reinstall west (pip install west)
    4. Follow the NCS installation guide once more

    Best regards,
    Carl Richard

  • Hi Carl again,

    Thanks a lot for this information. I tried it, but again without success. I installed everything on my Windows, but now I have a problem with header files, how to include them in Segger? I can run the samples and open JLinkRTTViewer to see outputs, but for example "battery.h" or "hts.h" header files are not included. Do you maybe know how can I fix this problem?

    Best regards, 

    Adnan. 

  • Hi again, Adnan!

    Sorry to hear that the Linux installation did not work out. Glad to hear that you're trying on windows!

    To include header files in Zephyr (and the nRF Connect SDK) you have to use edit CMakeLists.txt so that CMake is aware of your other files. Have a look at the sample I've attached, where a module "mult.h" has been included in the hello_world sample.

    3704.header_sample.zip

    When editing CMakeLists.txt, make sure to reload the project in SES afterwards.

    Best regards,
    Carl Richard

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