Basics Blinky, DC Motor, PhotoResistor

EPO Summer Camp Week 1 Arduino UNO Basics that can be reused:  

Blinking LED, DC Motor, Dim LED, read Photo-resistor

Overview

•  Blinking LED  using digitalWrite to send power signal  HIGH for on or LOW for off
•  Dim LED using analogWrite to send power signal (0-255)
•  DC Motor  reuse code for blinking  and din LED to power motor on/off or vary speed
•  Photoresistor senor  
•  reuse circuit just replacing LED with sensor  
•  change code analogRead to light read value 

Using Arduino SW from here:  https://www.arduino.cc/en/main/software

Connection Overview (in words)

All 4 projects can use Arduino pin 3 for output or input. Pin 3 was chosen because it is a PWM pin, which allows it to write and read analog signals.( More on PWM in week 2 Stepper Motors.) However A0, analog pin 0 can also be used for analog examples.

The 300 Ohm resistor is needed for LED and analog sensor. The DC motor needs electronics, which supplied by the L9110S H Bridge.

• Arduino Pin 3 to LED + on breadboard
• Pin 3 is also a PWM pin
• digital PWM pins are marked with a tilde, ~  and can be used with analogWrite()
• LED - on breadboard to 220 Ohm resistor
• Other side of resistor to GND on Arduino 

Code Overview

Setting up

• define variables - global and constant
•  int myDelay = 2000;  // Time on and off in milliseconds so 1000 = 1 sec
• In  setup() 
•  setup the pin(s) used: pinMode(3,OUTPUT); or pinMode(3,INPUT);
•  Serial.begin(9600); // set-up to use Serial.println(x);  baud is how fast; 9600 is standard
• In loop() define any local variables.  Like saving sensor value to print or react to it.

in loop() - repeatly called

• digitalWrite for on/ off  or min/ max control only
• analogWrite(PWM 0-255) for %power  and direction control (on digital PWM ~ pins)
•     LED brightness
•     Motor speed
• analogRead(A1) for input (0-255) from analog sensor like photo-resistor
• Analog pins are read only

Blinky

The HW Hello World. Turn something on and off. This circuit and both digital and analog code can be reused.

Digital - just on/off = Blinky

  digitalWrite(3,HIGH); 

  delay(myDelay); 

  digitalWrite(3,LOW); 

  delay(myDelay); 

Dim LED

Analog - vary the power so the LED is brighter or dimmer. 

So on/dim (instead of off)

   // range of power 0-255

  analogWrite(3,200);  // Bright

  delay(myDelay); 

  analogWrite(3,20); // Dim (very small looks like its off)  

  delay(myDelay);

 

Analog - pin reads in value from the analog sensor.

  int lt = analogRead(A1); 

  Serial.println(lt);

DC Motor

Reuse Blinky code using Analog  for DC motor to run fast (200) then very slow (20).

Uses L9110S DC Stepper Motor Driver H Bridge 

• short video: Arduino - DC Motor Tutorial (EPO by Caz) Note: 255 is fast (not 10)
• long video: How to control 2 DC motors using L9110s motor driver module with Arduino code

Connection Overview (in words)

H Bridge to Arduino

• VCC signal (power +) on H-Bridge to Arduino Pin 3
• GND on Arduino to  H-Bridge to Arduino Pin 3
• Power to 3.3V

H Bridge to motor

• red to 1 side of motor
• black to other side of motor
• side picked decides "polarity" of motor and direction it turns
• need for understanding driving wheels to move See Avoiding Obstacles post later (coming)

Photoresistor

Connection Overview (in words) 

• Arduino Pin 3 to Photoresistor - on breadboard where resistor starts.
• Other side of Photoresistor power (3.3V) to Arduino 3.3 V power
• GND on H-bridge to Arduino  GND