## Sunday, 9 December 2012

### Raspberry Pi - GPIO Game - How many times can you press it?

Anyway, I decided to see if I could make a game with the GPIO and learn a bit more about the GPIO and how to use it.

The concept is really simple, how many times can you press a button in 2 seconds?  My current record is 20.

The game counts you in, 5 leds lit, 4, 3, 2, 1 then you press it as many times are you can, it counts up in binary on 5 leds, before showing your high score in binary.

I used 5 leds and one button, connected to the Pi in the following configuration.

Gnd -> 10k resistor (pull down) -> Button -> GPIO 4 -> 1k resistor (protection) -> 3v

GPIO 17 -> Resistor -> LED -> Gnd
GPIO 18 -> Resistor -> LED -> Gnd
GPIO 21 -> Resistor -> LED -> Gnd
GPIO 22 -> Resistor -> LED -> Gnd
GPIO 23 -> Resistor -> LED -> Gnd

The leds are configured in a binary sequence going:

I then wrote the following python program:

nano superpress.py

import RPi.GPIO as GPIO
import time

# led gpio pins
ledGPIOPins = [17,18,21,22,23]
# button gpio pin
buttonPin = 4
# button pressed state
buttonPressedState = False
# lenght of game in seconds
gameTime = 2

# animations, [[value to display, delay][repeat]]
countToTenAnim = [[1,1],[2,1],[3,1],[4,1],[5,1],[6,1],[7,1],[8,1],[10,1]]
outInAndBackAnim = [[17,1],[10,0.5],[4,0.25],[0,0.1],[4,0.25],[10,0.5],[17,1]]
upAndDownAnim = [[1,0.2],[3,0.2],[7,0.2],[15,0.2],[31,0.2],[15,0.2],[7,0.2],[3,0.2],[1,0.2],[0,0.2]]
countDownAnim = [[31,0.2],[15,0.2],[7,0.2],[3,0.2],[1,0.2],[0,0]]
allFlash = [[31,0.5],[0,0.2],[31,0.5],[0,0.2],[31,0.5],[0,0.2]]

def setupGPIO():
# set gpio mode to use BCM pin numbers
GPIO.setmode(GPIO.BCM)
# loop through GPIO pins and set to output
for ledGPIOPin in ledGPIOPins:
# setup gpio pin as output
GPIO.setup(ledGPIOPin, GPIO.OUT)

def setLeds(ledGPIOValues):
ledGPIOPin = 0
# loop through led values, setting to appropriate GPIO pin
for ledGPIOValue in ledGPIOValues:
GPIO.output(ledGPIOPins[ledGPIOPin], ledGPIOValue)
ledGPIOPin = ledGPIOPin + 1

def display(number):
binary = ""
# reset led values
ledGPIOValues = [False, False, False, False, False]
# if number is greater than 5 bit, set it to the maximum
if number > 31 : number = 31

# calculate binary as a list of True & False
remainingValue = number
digit = 0
while remainingValue > 0:
if remainingValue % 2 == 1:
ledGPIOValues[digit] = True
binary = "1" + binary
remainingValue = remainingValue - 1
else:
ledGPIOValues[digit] = False
binary = "0" + binary
remainingValue = remainingValue / 2
digit = digit + 1

#output value to leds
setLeds(ledGPIOValues)

def displayAnimation(animation):
for frame in animation:
display(frame[0])
time.sleep(frame[1])

#class to control button
class Button:
# initialise button
def __init__(self, gpioPin, pressedState):
self.gpioPin = gpioPin
self.pressedState = pressedState
# setup button gpio pin as input
GPIO.setup(self.gpioPin, GPIO.IN)
# get initial button value
self.lastButtonValue = GPIO.input(self.gpioPin)

return GPIO.input(self.gpioPin)

# monitor the button, return true if button has been pressed since last run
def monitorPressed(self):
buttonPressed = False
currentButtonValue = GPIO.input(self.gpioPin)
# has value changed (i.e. pressed or unpressed)
if currentButtonValue != self.lastButtonValue:
# was the button pressed
if currentButtonValue == self.pressedState:
buttonPressed = True
self.lastButtonValue = currentButtonValue
return buttonPressed

#main program
try:
setupGPIO()
# create button class
button = Button(buttonPin, buttonPressedState)
# set leds to off
display (0)
while True:
# press button to start game
if button.monitorPressed() == True:
print "game intro"
displayAnimation(countDownAnim)
print "game started"
buttonCount = 0
display(buttonCount)
timeStarted = time.time()
while (time.time() - timeStarted) < gameTime:
if button.monitorPressed() == True:
buttonCount = buttonCount + 1
display(buttonCount)
print "game finished"
displayAnimation(allFlash)
print "show score"
display(buttonCount)
# wait
time.sleep(0.01)

except KeyboardInterrupt:
# cleanup GPIO
GPIO.cleanup()

Run the game

sudo python superpress.py

Press the button like a maniac...  If you beat 20, leave me a comment, but I want proof!

1. Hi, I really enjoyed reading your tutorial. I noticed that on the breadboard there was an extension board thing labelled as gnd. I was just wondering what it was and whether it is okay to plug jumper cables straight into the GPIO pins in my Pi instead of using one of these. Thank you :)

1. Hi,

The extension board is just a GPIO breakout, so I can connect a ribbon cable to the Pi. See this one from adafruit http://www.adafruit.com/products/914

You can just connect the cables direct to the Pi. No problems at all.

Mart