Arduino experiments

Planned experiments:

Hello world

  blink LED  on pin 13.

/* hello world */

int ledpin = 13;

void setup(){
  pinMode(ledpin,OUTPUT);
}

void loop(){
  digitalWrite(ledpin,LOW);
  delay(500);                    // off for 0.5 sec
  digitalWrite(ledpin,HIGH);
  delay(500);                    // on for 0.5 sec
}

Running light

  use LED board connected to pin 8,9,10,11,12,13 (six LEDs)
  each LED will be on for 250 ms

/* running light */

int ledpin[] = {8,9,10,11,12,13};

void setup(){
  int i;
  for(i=0; i < 6; i++){
    pinMode(ledpin[i],OUTPUT);
    digitalWrite(ledpin[i],HIGH);
  }
}

void loop(){
  int i;
  for(i=0; i < 6; i++){
    digitalWrite(ledpin[i],LOW);
    delay(250);
    digitalWrite(ledpin[i],HIGH);
  }
}

Push switch to toggle light

  push switch (pin 2) to toggle LED pin 13
  must debounce the switch signal

#define ledpin 13
#define switch 2
bool state = LOW;
int thisread;
int lastread = HIGH;
long debounce;

void setup(){
  pinMode(switch, INPUT);
  pinMode(ledpin, OUTPUT);
}

void loop(){
  do{
    thisread = digitalRead(switch);
    if( thisread == lastread)  debounce = millis();
  } while ( (millis() - debounce) < 50 );    // debounce period 50 ms

  if( thisread == LOW && lastread == HIGH){  // switch is pushed
   digitalWrite(ledpin,state);
   state = !state;                           // toggle state
  }
  lastread = thisread ;                      // update switch state
}


last update 1 Apr 2018  (no, this is definitely no an April fool)

Wiggle a servo

control position of a servo
use the library ET_SERVO   (download here) unzip and put it in arduino/libraries

#include <ET_SERVO.h>

ET_SERVO servo1;    // create a servo object

void setup(){
  servo1.attach(9,1000,2000);    // control at pin 9
}

void loop(){
  servo1.updateDutyCycle(1000);  // pulse width 1ms
  delay(1000);                   // wait one second
  servo1.updateDutyCycle(1500);  // pulse width 1.5ms
  delay(1000);
}
 
last update 28 Apr 2019  (end of lecture)