Photon 2 Microcontroller

Photon 2 Microcontroller

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Microcontroller

  • Microcontrollers (MCU) are embedded computers
  • They are often designed for a specific purpose (e.g. microwave, RC car, TV remote)
  • Microcontrollers can take input, process it, store a value, and produce output (like on your computer)
  • Unlike your computer (or even your phone), a microcontroller has very limited processing power and storage
  • Ex: The newer smartphones have 100,000 times more storage than the Photon 2

Particle Photon 2

  • We will develop projects for a microcontroller called an Photon 2 made by Particle
  • The Photon 2 is able to wirelessly connect to the internet and to Bluetooth
  • Particle also has a cloud communication system we will explore later in the semester

Datasheet

  • One important skill of building smart devices is learning to understand a datasheet
  • A datasheet explains how a component functions, how to use it, what conditions it will operate, etc.

  • Don’t worry about understanding everything in a datasheet, but learn to pull out key information

  • Photon 2 Datasheet

Work in groups and answer the following

  1. What voltage does the Photon 2 operate at?
  2. Which IC (integrated circuit) is the “main” processor?
  3. What is the difference between pins 3v3 and VUSB?
  4. How many digital input pins are there?
  5. How many analog output pins are there?
  6. How many ground pins are there?
  7. What is the voltage that the input pins can handle?
  8. Can we power the Photon 2 with battery?

Datasheet

Structure of Photon 2 Programs

  • We will use Particle Workbench as our IDE
  • We will write software code that runs on the Photon 2
  • Programs that run on microcontrollers are called firmware

Important Note

  • Your Photon 2 folder name cannot contain any spaces at all
    • C:\Users\Rob\ITP-348\Projects is ok
    • c:\Users\Rob Parke\ITP 348\Cool Projects is not

Key features

  • Photon 2 programs are written in C++ (please see review link on course website for C++)
  • Every Photon 2 program must have these two functions (you can other ones too)
    • void setup()
    • void loop()
  • In addition, most programs will also have
    • global variable declarations
    • library includes

Example program

#include "OLED_screen.h"	//library

const int MAX_PRESSES = 4;	//globcal constant
int numPresses = 0;			//global variable

void setup() {
  // put your setup code here, to run once:
}

void loop() {
  // put your main code here, to run repeatedly:
}

Note: There will be other default code at the top of the file when you create a new project. This code is needed to configure the Photon, but we can mostly ignore it

Libraries

#include "OLED_screen.h"
  • Similar to import
  • Allows us to access additional code and functions
  • We will use this to communicate with certain devices like LCD screens
  • Notice the #

Variable Declaration

const int MAX_PRESSES = 4;	//globcal constant
int numPresses = 0;			//global variable
  • Typically, many of our variables will be global (declared outside a function in the global namespace)
  • In C++, every variable must explicitly declare it’s

setup() Function

void setup() {
  // put your setup code here, to run once:
}
  • The setup() function will only run once
    • Runs after each powerup or reset the Photon 2
  • Use it to initialize variables, pin modes, start using libraries, etc.

loop() Function

void loop() {
  // put your main code here, to run repeatedly:
}
  • After setup() is called once, theloop() function is called endlessly
    • Basically an infinite loop
  • Use it for the main functionality of your program

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