Build a Raspberry Pi Scratch Game of Chance

2022-12-22 | By Maker.io Staff

License: See Original Project

You’ve probably flipped a coin to make some sort of trivial decision with your ‎friends, but what if we told you that you can make that coin flip a bit more ‎interesting? Or that flipping a coin could be turned into its own game?‎

In this project, we’ll show you how to get away from the manual approach to ‎flipping the coin and instead use an embedded computer-based game that can be ‎realized with the Raspberry Pi and a Sense HAT. Think of this as flipping the Coin ‎‎2.0: you’ll be guessing when a cat sprite lands on its feet. Even if you don’t use it ‎to replace your trusty favorite coin, it is still a fun project to work on!‎

Read below to learn more!‎

Reinventing the Coin Flip with the Gyro-Cat Scratch Game

Building the Gyro-Cat Scratch Game requires two main electronic components: a ‎Raspberry Pi and a Raspberry Pi (RPi) Sense HAT. The Sense HAT uses an 8x8 ‎matrix of addressable LEDs that can display various characters, scrolling text, and ‎numbers. With an 8x8 matrix, the Sense HAT provides 64 pixels for displaying ‎visual information. ‎

hat_1

The RPI Sense HAT.‎

Interacting with the Gyro Cat will require the player to start the flip using a ‎joystick. The RPi Sense HAT has a small joystick at the bottom right corner of the ‎printed circuit board (PCB). By pushing the RPI Sense HAT joystick in the upward ‎direction, the Raspberry Pi will move the Scratch cat sprite in an upward spiral ‎motion on the screen of the attached monitor. ‎

joystick_2

The RPI Sense HAT joystick.‎

The Raspberry Pi single-board computer (SBC) will provide the visual and audible ‎effects of the game using an attached monitor and speakers. The joystick position ‎data will be transferred to the Raspberry Pi from the RPi Sense HAT through the ‎‎40-pin connector. The Scratch cat rotational movement will be displayed on the ‎attached monitor using the Scratch blockly code programming language. There is ‎a cat meow sound produced using the Scratch sound code block.‎

The assembly of the Raspberry Pi and the RPi Sense HAT is illustrated below, and ‎you can see the parts list for this project in the following Scheme-it link: ‎https://www.digikey.com/schemeit/project/gyro-cat-scratch-game-‎fde79a6d1217495aa79c45d5c5f76002‎

assembly_3

The red transparency is added to make the scrolling messages easier to see.‎

console_4

The assembled Raspberry Pi Sense HAT game console

Using the Scratch Blockly Code

This Gyro Cat game software is built using Scratch, which is included with the ‎Raspberry Pi operating system. The game was developed in three sections: the ‎Start-player, the Timer, and the Reset player. The Start-player code allows the ‎game to be initiated by clicking the on-screen green flag in the stage window. ‎

With the green flag clicked, the title of the game scrolls across the LED matrix, as ‎shown below.‎

feature_5 ‎ ‎

The Gyro Cat scrolling title feature

Within the code structure, there is a conditional statement that looks for the ‎joystick being pushed upward by the player. When the joystick is pushed upward, ‎the cat will move and turn in a 10-step, - 90˚, and 30-step sequence. The code ‎used for checking the joystick position and sequencing the Scratch cat movements ‎is captured within a loop. The loop will run continuously until the player clicks the ‎on-screen red stop sign. ‎

Below are the code blocks for the Start-player game section. The sequence can be ‎modified to provide new sprite movements for the game by changing the move ‎and turn code blocks. ‎

blocks_6

The Start-player code blocks

The Timer section consists of code blocks that allow a 10-second window of play ‎within the game. The timer is initiated by the player tapping the spacebar on the ‎keyboard. The word Go is displayed on the Scratch stage, as shown below. ‎

go_7

Using the joystick, the player will move the Scratch sprite in a spiral matter. An ‎up-release motion with the joystick will allow the spiral motion to occur. Upon the ‎‎10-second timer elapsing, the Game-Over message will scroll across the RPi Sense ‎HAT LED matrix, and a cat meow sound will then be played. The Timer code blocks ‎are shown here:‎

timer_8

The final section for the Gyro Cat Scratch game is the Reset-player mode. This ‎section of code will allow the player to start a new game session by placing the ‎Scratch sprite back on its feet when the joystick is pressed down. The sprite will be ‎oriented 90˚ and placed at XY coordinates of (3,29). The Reset-player code is ‎shown here: ‎

view_9