Week 13 - Output Devices

Tasks:
To add an output device to a microcontroller board designed and program it to do something

Microcontroller: DIY ATmega328P based micro-controller.

Output device selected: 1-channel Relay module-10A.

Measurement criteria: To open and closed the relay in every 5 seconds interval continuously. N.B. There is also on-board LED to indicate the working status.

 

Micro-controller

The micro-controller for Output Devices is the same as Input Devices. The relay module has 3 pins too ie. IN, GND, and Vcc. In ATmega328, IN is connected to pin PD5. Eventually, the relay will use in final project, ie. to cut-off power supply to 3D printer.

 

Programming

The following program is written into the Arduino sketch and uploaded into the micro-controller.

	#include <SoftwareSerial.h>
	int Relay = 5;
  
	void setup()
	{
  	pinMode(13, OUTPUT);        //Set Pin13 as ATmega328's LED Output
  	digitalWrite(13, HIGH);     //Set Pin13 High
  	pinMode(Relay, OUTPUT);     //Set Pin5 as relay output
	}
	void loop()
	{
          digitalWrite(Relay, HIGH);   //Turn off relay
          delay(5000);
          digitalWrite(Relay, LOW);    //Turn on relay
          delay(5000);
	}
	

 

Measurement

The following shows the result:

 

Small DC Motor as Output with Speed Input through Serial Monitor

The following are the components needed to perform this task.

A Micro-controller (in this case, the same micro-controller as the above is used).

A Small DC Motor.

A "PN2222A" Transistor.

A "1N4001" diode.

A Resistor 270 Ohm.

Referring closely to "learn.adafruit.com", additional board to control the motor (see the following) is designed and milled.

The micro-controller board and the DC motor board are connected through jumper wires (refer to video below).

 

Programming

The following program is written into the Arduino sketch and uploaded into the micro-controller through FTDI.

	#include <SoftwareSerial.h>
	int motorPin = 5;
 
     void setup() 
     { 
      pinMode(motorPin, OUTPUT);
      Serial.begin(9600);
      while (! Serial);
      Serial.println("Speed 0 to 255"); // number increases with speed
     } 
 
     void loop() 
     { 
     if (Serial.available())
     {
      int speed = Serial.parseInt();
      if (speed >= 0 && speed <= 255)
     {
       analogWrite(motorPin, speed);
       }
      }
     }
	

 

The Result

The working files can be downloaded here.
Relay
Small DC Motor
DC-motor board and DC-motor schematic