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#!/usr/bin/env python3
import RPi.GPIO as GPIO
import time
#class Key:Define some of the properties of Key
class Key(object):
NO_KEY = '\0'
#Defines the four states of Key
IDLE = 0
PRESSED = 1
HOLD = 2
RELEASED = 3
#define OPEN and CLOSED
OPEN = 0
CLOSED =1
#constructor
def __init__(self):
self.kchar = self.NO_KEY
self.kstate = self.IDLE
self.kcode = -1
self.stateChanged = False
class Keypad(object):
NULL = '\0'
LIST_MAX = 10 #Max number of keys on the active list.
MAPSIZE = 10 #MAPSIZE is the number of rows (times 16 columns)
bitMap = [0]*MAPSIZE
key = [Key()]*LIST_MAX
holdTime = 500 #key hold time
holdTimer = 0
startTime = 0
#Allows custom keymap, pin configuration, and keypad sizes.
def __init__(self,usrKeyMap,row_Pins,col_Pins,num_Rows,num_Cols):
GPIO.setmode(GPIO.BOARD)
self.rowPins = row_Pins
self.colPins = col_Pins
self.numRows = num_Rows
self.numCols = num_Cols
self.keymap = usrKeyMap
self.setDebounceTime(10)
#Returns a single key only. Retained for backwards compatibility.
def getKey(self):
single_key = True
if(self.getKeys() and self.key[0].stateChanged and (self.key[0].kstate == self.key[0].PRESSED)):
return self.key[0].kchar
single_key = False
return self.key[0].NO_KEY
#Populate the key list.
def getKeys(self):
keyActivity = False
#Limit how often the keypad is scanned.
if((time.time() - self.startTime) > self.debounceTime*0.001):
self.scanKeys()
keyActivity = self.updateList()
self.startTime = time.time()
return keyActivity
#Hardware scan ,the result store in bitMap
def scanKeys(self):
#Re-intialize the row pins. Allows sharing these pins with other hardware.
for pin_r in self.rowPins:
GPIO.setup(pin_r,GPIO.IN,pull_up_down = GPIO.PUD_UP)
#bitMap stores ALL the keys that are being pressed.
for pin_c in self.colPins:
GPIO.setup(pin_c,GPIO.OUT)
GPIO.output(pin_c,GPIO.LOW)
for r in self.rowPins: #keypress is active low so invert to high.
self.bitMap[self.rowPins.index(r)] = self.bitWrite(self.bitMap[self.rowPins.index(r)],self.colPins.index(pin_c),not GPIO.input(r))
#Set pin to high impedance input. Effectively ends column pulse.
GPIO.output(pin_c,GPIO.HIGH)
GPIO.setup(pin_c,GPIO.IN)
#Manage the list without rearranging the keys. Returns true if any keys on the list changed state.
def updateList(self):
anyActivity = False
kk = Key()
#Delete any IDLE keys
for i in range(self.LIST_MAX):
if(self.key[i].kstate == kk.IDLE):
self.key[i].kchar = kk.NO_KEY
self.key[i].kcode = -1
self.key[i].stateChanged = False
# Add new keys to empty slots in the key list.
for r in range(self.numRows):
for c in range(self.numCols):
button = self.bitRead(self.bitMap[r],c)
keyChar = self.keymap[r * self.numCols +c]
keyCode = r * self.numCols +c
idx = self.findInList(keyCode)
#Key is already on the list so set its next state.
if(idx > -1):
self.nextKeyState(idx,button)
#Key is NOT on the list so add it.
if((idx == -1) and button):
for i in range(self.LIST_MAX):
if(self.key[i].kchar == kk.NO_KEY): #Find an empty slot or don't add key to list.
self.key[i].kchar = keyChar
self.key[i].kcode = keyCode
self.key[i].kstate = kk.IDLE #Keys NOT on the list have an initial state of IDLE.
self.nextKeyState(i,button)
break #Don't fill all the empty slots with the same key.
#Report if the user changed the state of any key.
for i in range(self.LIST_MAX):
if(self.key[i].stateChanged):
anyActivity = True
return anyActivity
#This function is a state machine but is also used for debouncing the keys.
def nextKeyState(self,idx, button):
self.key[idx].stateChanged = False
kk = Key()
if(self.key[idx].kstate == kk.IDLE):
if(button == kk.CLOSED):
self.transitionTo(idx,kk.PRESSED)
self.holdTimer = time.time() #Get ready for next HOLD state.
elif(self.key[idx].kstate == kk.PRESSED):
if((time.time() - self.holdTimer) > self.holdTime*0.001): #Waiting for a key HOLD...
self.transitionTo(idx,kk.HOLD)
elif(button == kk.OPEN): # or for a key to be RELEASED.
self.transitionTo(idx,kk.RELEASED)
elif(self.key[idx].kstate == kk.HOLD):
if(button == kk.OPEN):
self.transitionTo(idx,kk.RELEASED)
elif(self.key[idx].kstate == kk.RELEASED):
self.transitionTo(idx,kk.IDLE)
def transitionTo(self,idx,nextState):
self.key[idx].kstate = nextState
self.key[idx].stateChanged = True
#Search by code for a key in the list of active keys.
#Returns -1 if not found or the index into the list of active keys.
def findInList(self,keyCode):
for i in range(self.LIST_MAX):
if(self.key[i].kcode == keyCode):
return i
return -1
#set Debounce Time, The default is 50ms
def setDebounceTime(self,ms):
self.debounceTime = ms
#set HoldTime,The default is 500ms
def setHoldTime(self,ms):
self.holdTime = ms
#
def isPressed(keyChar):
for i in range(self.LIST_MAX):
if(self.key[i].kchar == keyChar):
if(self.key[i].kstate == self.self.key[i].PRESSED and self.key[i].stateChanged):
return True
return False
#
def waitForKey():
kk = Key()
waitKey = kk.NO_KEY
while(waitKey == kk.NO_KEY):
waitKey = getKey()
return waitKey
def getState():
return self.key[0].kstate
#
def keyStateChanged():
return self.key[0].stateChanged
def bitWrite(self,x,n,b):
if(b):
x |= (1<<n)
else:
x &=(~(1<<n))
return x
def bitRead(self,x,n):
if((x>>n)&1 == 1):
return True
else:
return False
ROWS = 4
COLS = 4
keys = [ '1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D' ]
rowsPins = [12,16,18,22]
colsPins = [19,15,13,11]
def loop():
keypad = Keypad(keys,rowsPins,colsPins,ROWS,COLS)
keypad.setDebounceTime(50)
while(True):
key = keypad.getKey()
if(key != keypad.NULL):
print ("You Pressed Key : %c "%(key) )
if __name__ == '__main__': # Program start from here
print ("Program is starting ... ")
try:
loop()
except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program destroy() will be executed.
pass
GPIO.cleanup()
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