A typical journey of an IoT device on a first boot is:

1. Connect to WiFi network
2. Check for firmware update (download and install if available)
3. Connect to all the online services it has to connect to
4. Start doing whatever it was built to do

The problem is: how would a device know which WiFi to connect to? Or how would it know that configuration of the communication network has changed?

That's when EspBootstrap comes to rescue: you can quickly provision initial configuration parameters, get your device connected to the WiFi, load, parse and store to EEPROM full set of configuration parameters, and be ready for doing whatever amazing things you plan to do.

EspBootstrap consists of three major components:

Parameters - a helper class that simplifies storing and loading configuration parameters in the EEPROM memory or SPIFFS filesystem of a device.

EspBootstrap - a helper class to quickly collect configuration parameter values from a user via simple web form in an Access Point mode

JsonConfig - a helper class to download/read and parse configuration file (simple JSON format) and populate respective configuration parameters

Both direct structure mapping and use of Dictionary data type is supported. Using dictionary is a simpler way, but may not be suitable for AVR devices with small memory.

Dictionary approach is the default.

(see example #2)

1. Create a Dictionary object (Make sure there is a "Title" key created as a first dictionary element for the web form)
2. Pass dictionary to appropriate ESPBootstrap and JSONConfig objects to load or obtain configuration from a user, device file system and/or from the web

1. Attempt to load parameters from EEPROM or file (fails first time since nothing was ever saved)

2. Collect initial configuration parameters via web form (http://10.1.1.1) created by ESPBootstrap (typically a WiFi SSID, password and a link to web-based configuration service)

   NOTE: fields with key containing words "password" or "pwd" will have characters masked with a * symbol.

3. Reboot and connect to WiFi with the recently obtained credentials

4. Load JSON configuration file from the web service or filesystem using JSONConfig and populate respective configuration parameters into the provided dictionary object

5. Save new configuration to EEPROM or file

6. Check for OTA update, download, install and reboot if update is available

7. Resume normal operation, periodically checking for OTA updates and config changes.

(see example #1)

1. Define Parameters Structure
2. Define Parameter "defaults"
3. Describe Parameter structure layout for ESPBootstrap and JSONConfig
4. Load or obtain configuration from a user and/or from the web

1. Attempt to load parameters from EEPROM/filesystem (fails first time since nothing was ever saved)
2. Collect initial configuration parameters via web form (http://10.1.1.1) created by EspBootstrap (typically a WiFi SSID, password and a link to web-based configuration service)
3. Reboot and connect to WiFi with the recently obtained credentials
4. Load JSON configuration file from the web service or a file using JsonWebConfig and populate respective configuration parameters
5. Save new configuration to EEPROM or to the filesystem
6. Check for OTA update, download, install and reboot if update is available
7. Resume normal operation, periodically checking for OTA updates and config changes.

Types of Parameters, JsonConfig and EspBootstrap objects should be chosen based on where you want to store your configuration and where you want to source your updates from:

#include <ParametersEEPROM.h>
#include <EspBootstrapDict.h>
#include <JsonConfigHttp.h>

See examples #2 and #3 (3 and 3b) for implementation details.

#include <ParametersEEPROMMap.h>
#include <EspBootstrapMap.h>
#include <JsonConfigHttpMap.h>

See example #1 for implementation details.

#include <ParametersSPIFFS.h>
#include <EspBootstrapDict.h>

Parameters object uses JsonConfig file load/save capability to store the parameters.

See examples #4 and #5 for implementation details.

EspBootstrapDict
EspBootstrapMap

ESPBootstrap - static object to use for processing (correct type is assigned)

JsonConfigHTTP
JsonConfigHTTPMap
JsonConfigSPIFFS
JsonConfigSPIFFSMap
    
JSONConfig - static object to use for processing (correct type is assigned)

ParametersEEPROM
ParametersEEPROMMap
ParametersSPIFFS

If additional storage or update types are required, they could be implemented later (e.g., ParametersSD or JsonConfigFTP)

NOTE: Only one type of storage is supported with the static ESPBootstrap and JSONConfig objects by default. This should cover 99% of the use cases. However, if you need to support multiple storage types, compile the library with _JSONCONFIG_NOSTATIC compile option and create appropriate objects explicitly.

#define PARAMS_OK   0
#define PARAMS_ERR  (-1)
#define PARAMS_LEN  (-2)
#define PARAMS_CRC  (-3)
#define PARAMS_TOK  (-4)
#define PARAMS_MEM  (-98)
#define PARAMS_ACT  (-99)

PARAMS_OK - operation finished successfully

PARAMS_ERR - operation finished with an error, unspecified

PARAMS_LEN - requested size or EPROM size is not sufficient to store parameters

PARAMS_CRC - data inconsistency between parameters in memory and in EEPROM

PARAMS_TOK - parameter tokens do not match

PARAMS_MEM - failed to allocate memory for parameters buffer

PARAMS_ACT - parameters engine was not activated with begin() method (not allocated)

#define BOOTSTRAP_OK        0
#define BOOTSTRAP_ERR      (-1)
#define BOOTSTRAP_TIMEOUT (-99)

BOOTSTRAP_OK - bootstrap was successful. Parameters were entered and stored. No timeouts.

BOOTSTRAP_ERR - bootstrap process ended with errors (e.g., webserver failed to initiate)

BOOTSTRAP_TIMEOUT - bootstrap process ran out of time waiting for user inputs.

#define JSON_OK         0
#define JSON_ERR      (-1)
#define JSON_COMMA    (-20)
#define JSON_COLON    (-21)
#define JSON_QUOTE    (-22)
#define JSON_BCKSL    (-23)
#define JSON_MEM      (-24)
#define JSON_FMT      (-25)
#define JSON_HTTPERR  (-97)
#define JSON_NOWIFI   (-98)
#define JSON_EOF      (-99)

JSON_OK - operation finished successfully. All fields were processed as expected.

JSON_ERR - operation finished with unspecified error (reserved for future use and/or testing)

JSON_COMMA - missing comma. (Detected ":" before detecting a value)

JSON_COLON - missing colon. (Detected a comma or a new line before detecting a value)

JSON_QUOTE - missing closing quotation mark

JSON_BCKSL - orphaned back-slash. Back-slash not followed by a "verbatim" character.

JSON_MEM - error allocating memory for dictionary entry

JSON_FMT - incorrect JSON formatting (invalid character)

JSON_HTTPERR - general HTTP error. Cannot initiate a connection to provided URL.

JSON_NOWIFI - device is not connected to WiFi

JSON_EOF - unexpected end of file.

JsonConfig also returns all HTTP error codes in case of HTTP GET operation failure. For instance: 404 - page not found.