title: ESP8266 Arduino available memory
body: <p>When I compile a simple Blink sketch on Arduino for ESP8266, it looks like 38% of the memory is used by something:</p>
  
  <blockquote>
    <p>Global variables use 31,576 bytes (38%) of dynamic memory, leaving 50,344 bytes for local variables. Maximum is 81,920 bytes.</p>
  </blockquote>
  
  <p>Where does this memory go? I have an application that requires a lot of memory and wanted to see if I can disable / reduce usage by some Arduino built-in libraries.</p>
  
  <p>Code below:</p>
  
  <pre><code>void setup() {
    pinMode(LED_BUILTIN, OUTPUT);
    // Initialize the LED_BUILTIN pin as an output
  }
  
  void loop() {
    digitalWrite(LED_BUILTIN, LOW);
    // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is acive low on the ESP-01)
    delay(1000);
    // Wait for a second
    digitalWrite(LED_BUILTIN, HIGH);
    // Turn the LED off by making the voltage HIGH
    delay(2000);
    // Wait for two seconds (to demonstrate the active low LED)
  }
  </code></pre>