ESP32の設定管理ライブラリの紹介

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef _PREFERENCES_H_
#define _PREFERENCES_H_

#include "Arduino.h"

class Preferences {
    protected:
        uint32_t _handle;
        bool _started;
        bool _readOnly;
    public:
        Preferences();
        ~Preferences();

        bool begin(const char * name, bool readOnly=false);
        void end();

        bool clear();
        bool remove(const char * key);

        size_t putChar(const char* key, int8_t value);
        size_t putUChar(const char* key, uint8_t value);
        size_t putShort(const char* key, int16_t value);
        size_t putUShort(const char* key, uint16_t value);
        size_t putInt(const char* key, int32_t value);
        size_t putUInt(const char* key, uint32_t value);
        size_t putLong(const char* key, int32_t value);
        size_t putULong(const char* key, uint32_t value);
        size_t putLong64(const char* key, int64_t value);
        size_t putULong64(const char* key, uint64_t value);
        size_t putFloat(const char* key, float_t value);
        size_t putDouble(const char* key, double_t value);
        size_t putBool(const char* key, bool value);
        size_t putString(const char* key, const char* value);
        size_t putString(const char* key, String value);
        size_t putBytes(const char* key, const void* value, size_t len);

        int8_t getChar(const char* key, int8_t defaultValue = 0);
        uint8_t getUChar(const char* key, uint8_t defaultValue = 0);
        int16_t getShort(const char* key, int16_t defaultValue = 0);
        uint16_t getUShort(const char* key, uint16_t defaultValue = 0);
        int32_t getInt(const char* key, int32_t defaultValue = 0);
        uint32_t getUInt(const char* key, uint32_t defaultValue = 0);
        int32_t getLong(const char* key, int32_t defaultValue = 0);
        uint32_t getULong(const char* key, uint32_t defaultValue = 0);
        int64_t getLong64(const char* key, int64_t defaultValue = 0);
        uint64_t getULong64(const char* key, uint64_t defaultValue = 0);
        float_t getFloat(const char* key, float_t defaultValue = NAN);
        double_t getDouble(const char* key, double_t defaultValue = NAN);
        bool getBool(const char* key, bool defaultValue = false);
        size_t getString(const char* key, char* value, size_t maxLen);
        String getString(const char* key, String defaultValue = String());
        size_t getBytes(const char* key, void * buf, size_t maxLen);
};

#endif

/*
 ESP32 start counter example with Preferences library

 This simple example demonstrate using Preferences library to store how many times
 was ESP32 module started. Preferences library is wrapper around Non-volatile
 storage on ESP32 processor.

 created for arduino-esp32 09 Feb 2017
 by Martin Sloup (Arcao)
*/

#include <Preferences.h>

Preferences preferences;

void setup() {
  Serial.begin(115200);
  Serial.println();

  // Open Preferences with my-app namespace. Each application module, library, etc.
  // has to use namespace name to prevent key name collisions. We will open storage in
  // RW-mode (second parameter has to be false).
  // Note: Namespace name is limited to 15 chars
  preferences.begin("my-app", false);

  // Remove all preferences under opened namespace
  //preferences.clear();

  // Or remove the counter key only
  //preferences.remove("counter");

  // Get a counter value, if key is not exist return default value 0
  // Note: Key name is limited to 15 chars too
  unsigned int counter = preferences.getUInt("counter", 0);

  // Increase counter
  counter++;

  // Print counter to a Serial
  Serial.printf("Current counter value: %u\n", counter);

  // Store counter to the Preferences
  preferences.putUInt("counter", counter);

  // Close the Preferences
  preferences.end();

  // Wait 10 seconds
  Serial.println("Restarting in 2 seconds...");
  delay(2000);

  // Restart ESP
  ESP.restart();
}

void loop() {}