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Raspberry 4*4 keyboard code
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# ##################################################### | |
# Python Library for 4x4 matrix keypad using | |
# 7 of the avialable GPIO pins on the Raspberry Pi. | |
# | |
# This could easily be expanded to handle a 4x4 but I | |
# don't have one for testing. The KEYPAD constant | |
# would need to be updated. Also the setting/checking | |
# of the colVal part would need to be expanded to | |
# handle the extra column. | |
# | |
# Written by Chris Crumpacker | |
# May 2013 | |
# Modified by Tyrael Lau | |
# Sep 2016 | |
# | |
# main structure is adapted from Bandono's | |
# matrixQPI which is wiringPi based. | |
# https://github.com/bandono/matrixQPi?source=cc | |
# ##################################################### | |
import RPi.GPIO as GPIO | |
class keypad(): | |
# CONSTANTS | |
KEYPAD = [ | |
[1, 2, 3, "A"], | |
[4, 5, 6, "B"], | |
[7, 8, 9, "C"], | |
["*", 0, "#", "D"] | |
] | |
COLUMN = [25, 24, 23, 18] | |
ROW = [22, 21, 17, 4] | |
def __init__(self): | |
GPIO.setmode(GPIO.BCM) | |
def getKey(self): | |
# Set all columns as output low | |
for j in range(len(self.COLUMN)): | |
GPIO.setup(self.COLUMN[j], GPIO.OUT) | |
GPIO.output(self.COLUMN[j], GPIO.LOW) | |
# Set all rows as input | |
for i in range(len(self.ROW)): | |
GPIO.setup(self.ROW[i], GPIO.IN, pull_up_down=GPIO.PUD_UP) | |
# Scan rows for pushed key/button | |
# A valid key press should set "rowVal" between 0 and 3. | |
rowVal = -1 | |
for i in range(len(self.ROW)): | |
tmpRead = GPIO.input(self.ROW[i]) | |
if tmpRead == 0: | |
rowVal = i | |
# if rowVal is not 0 thru 3 then no button was pressed and we can exit | |
if rowVal <0 or rowVal >3: | |
self.exit() | |
return | |
# Convert columns to input | |
for j in range(len(self.COLUMN)): | |
GPIO.setup(self.COLUMN[j], GPIO.IN, pull_up_down=GPIO.PUD_DOWN) | |
# Switch the i-th row found from scan to output | |
GPIO.setup(self.ROW[rowVal], GPIO.OUT) | |
GPIO.output(self.ROW[rowVal], GPIO.HIGH) | |
# Scan columns for still-pushed key/button | |
# A valid key press should set "colVal" between 0 and 3. | |
colVal = -1 | |
for j in range(len(self.COLUMN)): | |
tmpRead = GPIO.input(self.COLUMN[j]) | |
if tmpRead == 1: | |
colVal=j | |
# if colVal is not 0 thru 3 then no button was pressed and we can exit | |
if colVal < 0 or colVal > 3: | |
self.exit() | |
return | |
# Return the value of the key pressed | |
self.exit() | |
return self.KEYPAD[rowVal][colVal] | |
def exit(self): | |
# Reinitialize all rows and columns as input at exit | |
for i in range(len(self.ROW)): | |
GPIO.setup(self.ROW[i], GPIO.IN, pull_up_down=GPIO.PUD_UP) | |
for j in range(len(self.COLUMN)): | |
GPIO.setup(self.COLUMN[j], GPIO.IN, pull_up_down=GPIO.PUD_UP) | |
if __name__ == '__main__': | |
# Initialize the keypad class | |
kp = keypad() | |
# Loop while waiting for a keypress | |
digit = None | |
while digit == None: | |
digit = kp.getKey() | |
# Print the result | |
print digit |
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