ESP32 startup counter example with Preferences library.

 This simple example demonstrates using the Preferences library to store how many times
 the ESP32 module has booted. The Preferences library is a wrapper around the Non-volatile
 storage on ESP32 processor.

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

#include <Preferences.h>

Preferences preferences;

void setup() {

  // Open Preferences with my-app namespace. Each application module, library, etc
  // has to use a 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 the opened namespace

  // Or remove the counter key only

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

  // Increase counter by 1

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

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

  // Close the Preferences

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

  // Restart ESP

void loop() {}