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Trinket Pinball 2016

https://git.io/vKKZZ

Basics

Uploading Code Plug your Trinket into USB and press the reset button. You can only upload code if the red LED is pulsing.

Program Template Every program you write needs to have the following:

#include <ewm.h>

void setup() {
  initPinball();
}

void loop() {

}

To include the library, select it from Sketch > Include Library.

C Syntax

We write code for the Trinket in the C programming language. Here are some tips for writing C code.

Semicolons [VERY IMPORTANT!] C uses semicolons (;) to know where lines of code end. Every line of code you write must have a semicolon at the end. The only exception is lines ending with curly brackets ({}), which do not need semicolons.

Comments Lines beginning with two slashes (//) are a comment, and are ignored by the Trinket. Use comments to leave notes for your future self, or to explain sections of complicated code.

Variables We can store information in variables. This is useful if you use one value many times throughout your program (like a delay time) or if you want to save values (like a score).

// Declaration (at the top of your file)
int foo = 0;

// Elsewhere in your code
foo = millis();
digitalWrite(foo, LOW);

You can use the following datatypes:

  • boolean – true or false. May also be used as HIGH and LOW, or 1 and 0.
  • byte – small, non-negative numbers (0 to 255), or eight individual bits. Used for advanced 7-segment programming.
  • int – medium sized numbers (-32767 to +32767). Most common.
  • long – large numbers (-2147483647 to +2147483647). Used for timing.
  • float – decimals like 0.5 or 17.625. All other numerical datatypes can only store whole numbers.

Functions are shortcuts to run chunks of code from a single line. Run them by writing their name followed by parentheses:

function();
doSomething();

Some functions take extra information in the form of arguments:

function(argument1, argument2);
blinkSeveralTimes(numberOfTimes);

Some functions return a value, which can be saved to a variable or treated as a number:

foo = function(argument(s));
startTime = getCurrentTime();
...
[other code]
...
timePassed = getCurrentTime() - startTime;

Conditionals allow you to run some code sometimes, and run other code other times.

Here's the format. Keep in mind that only one code block will run per conditional. So if the first condition is true, no other code will be run.

if(condition1) {
    // This code runs if condition1 is true
}
else if(condition2) {
    // condition1 is false and condition2 is true
}
else if(condition3)
{
    // conditions 1 & 2 are false and condition3 is true
}
else {
    // all the conditions are false
}

You can have as many else ifs as you want (or none). Writing an else is optional, but if you do use it, it must be last.

Loops come in two flavors. They allow you to run the same code many times over:

For loops are used for repeating code some number of times:

// Count to 100
for(int i = 0; i <= 100; i++) {
    displayNumber(i);
}

While loops are used for repeating code until some other condition becomes true.

while(score < 100) {
    // This code runs forever until score >= 100
}
// after the loop finishes, score >= 100

Math works just as it does outside of programming. Parentheses can be used to neaten things up.

  • a + b addition
  • a - b subtraction
  • a * b multiplication
  • a / b division
  • a % b modulo (remainder from division)

Boolean Operators make up conditional statements, and allow us to create boolean expressions. Remember from the datatypes intro; these have one of two states: true or false. A boolean expression can be one of the following:

  • a function that returns a boolean value, like digitalRead(pin)
  • a number (0 is false, all other numbers are true)
  • an (in)equality test:
    • a == b – is a equal to b?
    • a != b – is a not equal to b?
    • a > b – is a greater than b?
    • a >= b – is a greater than or equal to b?
    • a < b – is a less than b?
    • a <= b – is a less than or equal to b?
  • a compound expression:
    • a && b (and) – are both a and b true?
    • a || b (or) – is at least one of a or b true?
    • !a (not) – is a false?

Just like in math, use parentheses to combine expressions.

Arduino Code

Here are some Arduino functions you'll be using during the week.

digitalWrite(LED, state) controls digital pins – for us, that's just the LEDs. The LED argument can be:

  • BUMP_0_LED
  • BUMP_1_LED
  • BUMP_2_LED

and the state argument can be HIGH (on) or LOW (off).

digitalRead(sensor) reads the current state of a sensor, and returns either HIGH or LOW.

  • BUMP_0_SENSE, BUMP_1_SENSE, and BUMP_2_SENSE return LOW when they are pressed, and HIGH when they are not.
  • FLIP_L_SENSE and FLIP_R_SENSE return HIGH when they are pressed, and LOW when they are not.
  • OUT_SENSE and RAMP_SENSE return LOW when a marble is over them, and HIGH if not.

millis() returns the number of milliseconds since your program started running. There are 1000 milliseconds in one second.

micros() returns the number of microseconds since your program started running. There are 1000 microseconds in one millisecond, so there are 1,000,000 microseconds in one second.

delay(time) waits for a certain amount of time, given in milliseconds. All other code stops while your program is waiting. For example, delay(1000); waits for one second.

delayMicroseconds(time) waits for a certain amount of time, given in microseconds. This means that delayMicroseconds(1000); is the same as delay(1);.

random(min, max) returns a random integer between min (inclusive) and max (exclusive). So if you wanted a random number from 1 to 100, you would call random(1, 101);.

Library Code

To make writing code in this camp easier, we've written some behind-the-scenes code (called a "library") that contains many functions to help you use your pinball machine. However, this code is specific to this project, so it won't work if you try to program something else.

initPinball() sets up a lot of behind-the-scenes code for the pinball machine. This function must be the first line of your setup() function.

Servo

servoUp() moves the servo to the up position.

servoDown() moves the servo to the down position.

7-segment Display

displayNumber(n) displays a number.

displayText("text", delay) scrolls text at a specified speed.

clearDisplay() clears the display.

Speaker

tone(frequency) plays a tone at the specified frequency.

setSpeakerVolume(percent) sets the speaker volume (the default is 50 percent). Avoid using very high values to prevent damaging the speaker.

speakerOff() turns off the speaker.

Data Storage

updateHighScore(score) set the high score to score.

readHighScore() returns the high score.

clearHighScore() set the high score to zero.

updateGameCount() increments the game count by 1.

readGameCount() returns the game count.

clearGameCount() sets the game count to zero.

Motor

setMotorSpeed(percent) sets the motor speed (from 0 to 100 percent). Remember that using the motor can quickly drain the batteries.

Going Home

If you would like to work on your pinball machine at home, you'll need to install the Arduino software. Follow the "Super Easy Instructions" at this link:

https://learn.adafruit.com/adafruit-arduino-ide-setup/arduino-1-dot-6-x-ide