Initializing personal Settings and Bluetooth Whitelist

[rtroval]

Hello,

Hardware: nRF5340DK
SDK: v2.6.1
Context: Creating a prototype using a Load Cell and transmitting its weight on BLE.
Disclaimer: I'm new to the settings subsystem

The problem is that I use personnal settings to store the scale parameters (offset+slope) and the Bluetooth Whitelist on the same project.

Here is the order of main.c execution:

1. Load parameters for the scale
2. Create my threads (Scale / IHM / UART)
3. Create my BLE thread

When I order my program like this and build it using NSPE config (_ns), I get this error (SECURE FAULT).

When I build it using SPE config, I get this error (USAGE FAULT).

When restarting the DK, there is no error. So to reproduce the error a new "west flash" is needed.

When searching for an answer, I found this: Kconfig search (nordicsemi.com)
It stipulates that settings_load() should be called after bt_enable().

I personnally find it unnatural for my use case, because if I want to use another technology to read the weight (UART), I still need to call enable_ble().

I could use something like this: nRF SoC Internal Storage — Zephyr Project Documentation
But I find the  settings to better match my needs.

However if there is no solution possible, I might use this last solution.

How to reproduce:

1. Get this sample: bt-fund/lesson5/blefund_less5_exer2_solution at main · NordicDeveloperAcademy/bt-fund (github.com)
2. Add settings.c 
   
   Fullscreen settings.c Download

   #include "settings.h"
   #include <string.h>
   
   LOG_MODULE_REGISTER(settings_log, LOG_LEVEL_INF);
   
   #define CONFIG_SETTINGS_SUBTREE "config"
   #define CONFIG_SETTINGS_OFFSET_NAME       	CONFIG_SETTINGS_SUBTREE"/offset"
   #define CONFIG_SETTINGS_SLOPE_NAME      	CONFIG_SETTINGS_SUBTREE"/slope"
   
   
   /* Let's create a structure that we want to save */
   struct calib_param_t {
       uint32_t offset;
       double slope;
   };
   
   struct calib_param_t my_params;
   
   static int settings_handle_set(const char *name, size_t len,
                               settings_read_cb read_cb, void *cb_arg)
   {
       const char *next;
       size_t name_len;
       int rc;
   
       name_len = settings_name_next(name, &next);
   
       if (!next) {
   		if (!strncmp(name, "offset", name_len)) {
   			rc = read_cb(cb_arg, &my_params.offset, sizeof(my_params.offset));
   			return 0;
   		}
   
   		if (!strncmp(name, "slope", name_len)) {
   			rc = read_cb(cb_arg, &my_params.slope, sizeof(my_params.slope));
   			return 0;
   		}
   	}
   	return -ENOENT;
   }
   
   SETTINGS_STATIC_HANDLER_DEFINE(my_settings, CONFIG_SETTINGS_SUBTREE, 
   					NULL, settings_handle_set, NULL, NULL);
   
   int flash_init(){
       int err = 0;
       err = settings_subsys_init();
   	if (err){
   		LOG_ERR("Error while initializing the subsys : err = %d", err);
   		return -1;
   	}
   	// Loads the Whitelist for advertising + settings for param
   	err = settings_load();
   	if (err){
   		LOG_ERR("Error while loading settings : err = %d", err);
   		return -2;
   	}
       return err;
   }
   
   /**
    * GETTERS + SETTERS
    */
   
   uint32_t get_param_offset(void)
   {
       uint32_t offset = my_params.offset;
   	return offset;
   }
   
   int set_param_offset(uint32_t value)
   {
   	my_params.offset = value;
   	int ret = settings_save_one(CONFIG_SETTINGS_OFFSET_NAME, &value, sizeof(value));
       return ret;
   }
   
   double get_param_slope(void)
   {
       double slope = my_params.slope;
   	return slope;
   }
   
   int set_param_slope(double value)
   {
   	my_params.slope = value;
   	int ret = settings_save_one(CONFIG_SETTINGS_SLOPE_NAME, &value, sizeof(value));
       return ret;
   }
   

3. Add settings.h
   settings.h
4. Modify CMakeLists
   
   

   cmake_minimum_required(VERSION 3.20.0)
   
   find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
   project(NONE)
   
   FILE(GLOB app_sources   src/*.c)
   target_sources(app PRIVATE ${app_sources})
   
   zephyr_include_directories(src)

5. Modify main.c
   1. include "settings.h"
   2. define TRIGGER_ERROR 1 (it allows to trigger or not the error
   3. add this code just before bt_enable in main():
      

      	#if TRIGGER_ERROR
      	flash_init();
          k_msleep(30);
      
          int local_offset = get_param_offset();
          local_offset++;
          set_param_offset(local_offset);
      
          printk("offset: %d\n", local_offset);
      	#endif

   4. After bt_enable(), replace the settings_load() line with
      

      	#if TRIGGER_ERROR
      	/* STEP 1.3 - Add setting load function */
      	settings_load();
      	#else
      	flash_init();
          k_msleep(30);
      
          int local_offset = get_param_offset();
          local_offset++;
          set_param_offset(local_offset);
      
          printk("offset: %d\n", local_offset);
      	#endif

6. Build and flash

[rtroval]

I just found the problem:

When reading the Zephyr Documentation for bt_enable (here). 

It suggests using settings_load_subtree("bt") instead of settings_load()

So in my case you need to :

• Modify flash_init() in settings.c to replace settings_load(); with settings_load_subtree("config");
• Modify main() in main.c to replace settings_load(); (after bt_enable()) with settings_load_subtree("bt")