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+====== My Reaction / Research on julian's investigates how slow is arduino youtube video ======
+After i have seen Julian's YouTube Video ( https://youtu.be/U7I0GkwW1yE ) on Arduino Microcontrollers i was courious about if the Arduino is really that slow and so i wanted to test it myself, trying out multiple methods to switch on and of a single pin on the arduino as fast as we can. This Page summarizes my results and shows the oscilloscope (scope) Screenshots and code that i have made and used.
+===== The Task : Switch on and off a single arduino pin as fast as we possibly can using Arduino IDE (C language) =====
+Here is the Code i used to measure the different methods and ways to achieve that. Please note that i dont just run this Code with all the different methods enabled (uncommented), but uncomment one method a time.
+<code c>
+/**
+ * this is some test code to test arduino speed.
+ * just switching on and off one single digital pin as fast
+ * as i can, just to see and measure with an osciloscope how
+ * fast switching by C code can be achieved.
+ *
+ * Using an Arduino Uno at 16Mhz with Arduino IDE 1.6.7 (Linux)
+ * and a HAMEG (Rhode & Schwarz) HMO2024 Oscilloscope
+ *
+ * by Axel Werner [axel.werner.1973@gmail.com]
+ */
+#define PIN 12
+void setup() {
+  pinMode(PIN, OUTPUT);
+  noInterrupts();
+}
+void loop() {
+  /*
+   * Using the Arduinos own loop() function AND
+   * these "arduino" methods to set and reset a pin
+   * only gives me a maximum switching
+   * frequency of 94.6KHz at ca 48% duty cicle.
+   *
+   * See Scope Screenshot:
+   * http://www.awerner.myhome-server.de/lib/exe/fetch.php?media=it-artikel:arduino:test-how-fast-is-arduino-using-arduino-loop-digitalwrite.png
+   */
+//  digitalWrite(PIN,HIGH);
+//  digitalWrite(PIN,LOW);
+  /*
+   * Using the Arduino loop() function but using bit wise
+   * operation on a data register to loop through
+   * on and off state of a pin gives me a maximum switching
+   * frequency of 999KHz at ca 87.5% duty cicle .
+   *
+   * See Scope Screenshot:
+   * http://www.awerner.myhome-server.de/lib/exe/fetch.php?media=it-artikel:arduino:test-how-fast-is-arduino-using-arduino-loop-bitwise-setreset.png
+   */
+//  PORTB &= 0<<4; // PORT B Bit 4 is Arduino Pin 12
+//  PORTB |= 1<<4;
+  while(1){ // using my OWN (real) loop now...
+    /*
+     * with my own while loop and these "arduino" methods
+     * a maximum switching frequency of only ca. 97.5 KHz
+     * at a perfect 50% duty cicle has been achieved
+     * while the interupts where disabled.
+     */
+//    digitalWrite(PIN,HIGH);
+//    digitalWrite(PIN,LOW);
+    /*
+     * Both bit operation methods work effectively the same
+     * when it comes to timing. A maximum switching frequency of 2.66MHz at
+     * ca 66.8% duty cicle has been achieved. Even while Interrupts enabled.
+     *
+     * See Scope Screenshot:
+     * http://www.awerner.myhome-server.de/lib/exe/fetch.php?media=it-artikel:arduino:test-how-fast-is-arduino-using-own-while-loop-and-bitwise-setreset.png
+     */
+    //    PORTB = PORTB & B11101111; // clearing bit 4
+    //    PORTB = PORTB | B00010000; // setting bit 4
+    //    PORTB &= 0<<4; // Just another way to write it.
+    //    PORTB |= 1<<4;
+    PORTB &= 0<<PB4; // Yet another way to write it, using Atmels Port-/Register- and Pin-Names
+    PORTB |= 1<<PB4;
+  } // end of MY while loop.
+} // end of Arduinos loop() function.
+</code>
+See C Code for Screenshot-URLs. Just klick on them. Or see them here out of context.
+  * Using the Arduinos own loop() function AND these "arduino" methods to set and reset a pin only gives me a maximum switching frequency of 94.6KHz at ca 48% duty cicle. \\ {{:it-artikel:arduino:test-how-fast-is-arduino-using-arduino-loop-digitalwrite.png|}}
+  * Using the Arduino loop() function but using bit wise operation on a data register to loop through on and off state of a pin gives me a maximum switching frequency of 999KHz at ca 87.5% duty cicle . \\ {{:it-artikel:arduino:test-how-fast-is-arduino-using-arduino-loop-bitwise-setreset.png|}}
+  * With my own while loop and these "arduino" methods a maximum switching frequency of only ca. 97.5 KHz at a perfect 50% duty cicle has been achieved while the interupts where disabled.  \\ {{:it-artikel:arduino:test-how-fast-is-arduino-using-own-while-loop-and-bitwise-setreset.png|}}
+ --- //[[mail@awerner.myhome-server.de|Axel Werner]] 2016-01-28 16:55//
+{{tag>eev electronics arduino c microcontrollers}}