' KeyPad_RP2040_74HC595_2_Pin_v01.bas - Program 4x4 Key Pad
'
' Keypad reader using a 74HC595 and 2 MCU I/O pins.
' For more than 8 rows plus collums daisychain another 74HC595 chip or two.
' then adjust the Rows and Cols limits for the For / Next loops.
' 1 chip is up to 16 Keys, 2 is up to 64 (8 x 8), 3 is up to 144 (12 x 12)
' keypad does not need to be square. 2 chips = 16 outputs so could do 12 x 4 (12 + 4 = 16)
'  SetPin 22,dout: Pin(22)=0 : CLS 1  'N5110 LCD backlight
Text 9,6,Time$ : Text 2,25,Date$
Dim Integer Rows = 4, Cols = 4, Key = -1, OutPin=MM.Info(pinno GP0), InPin=MM.Info(pinno GP1)
SetPin OutPin,dout : Pin(OutPin)=1 'initialize keypad rows
HC595 OutPin,Rows+Cols,0
SetPin InPin,intl,KP_int,pullup 'initialize keypad columns

Sub KP_Int
  t=Timer
  Pause 2 'key de-bounce time, adjust to suit your keypad
  Local integer R, C

  For R=0 To Rows-1
   hc595 OutPin,Rows+Cols,15-(1<<R)
   If 1-Pin(InPin) Then Exit For
  Next
  hc595 OutPin,Rows+Cols,0

  For C=0 To Cols-1
   hc595 1,Rows+Cols, (15-(1<<C))<<4
   If 1-Pin(InPin) Then Exit For
  Next
  hc595 OutPin,Rows+Cols,0

  If Rows-R Then Key = R*4+C
End Sub

Sub HC595 Out.Pin As integer, RC As integer, Dat As integer 'Data output Pin, number of Rows+Cols, Word to output
  Pin(Out.Pin)=1 'ensure correct polarity for Bitstream
  Local integer n, el=RC*2-1, B(el)
  For n=0 To el Step 2 'prepare Bitstream array
    B(n)=3-(Dat>>(el-n)\2 And 1)*2 'low data pulses, 3uS=0 ,1uS=1
    B(n+1)=1 '1uS high spaces
  Next
  Device BITSTREAM Out.Pin, el+1, B() 'send it
  Pin(Out.Pin)=1 : Pause 0.04 ' >20uS high = latch clock
End Sub

Do
'   Text 9,6,Time$ : Text 2,25,Date$ 'for N5110 LCD
  If Key+1 Then Print "Key";Key, Timer-t;" mS" : Key = -1
Loop

End
'  74HC595 connections
' 3V3 to pins 16, 10
' Gnd to pins 8, 13
' BitStream input to pin 11 (clock)
' pin 11 - 1k8 - pin 14 (data in) - 1n5 - Gnd
' pin 11 - A-diode-K - pin 14 (ser. data in) eg 1N914 or 1N4148
' pin 11 - 4k7 - pin 12 (latch) - 1n5 - Gnd
' pin 11 - K-diode-A - pin 14 (latch)
' pin 9 (ser. data out) to next 74HC595 (if used) pin 14 (ser. data in),
' parallel pin 11 to pin 11 and pin 12 to pin 12
' 4x4 Row output pins:- 15, 1, 2, 3,
' 4x4 Column output pins:- 4, 5, 6, 7

' Keypad reader using a 74HC595 and 2 MCU I/O pins.
' For MicroMite Mk II v5.05.05, also PicoMite
' Can be expanded with more 74HC595 chips.
' 1 chip is up to 16 Keys, 2 is up to 64, 3 is up to 144
'  SetPin 22,dout : CLS 1 : Pin(22)=0 'LCD backlight
Option Default Integer
Option Base 0
Const Rows = 4, Cols = 4, OutPin = 4, InPin = 5
Dim Key = -1
Const RnC = Rows + Cols
Dim map$(15)=("1","2","3","A","4","5","6","B","7","8","9","C","*","0","#","D")
Dim Float t
SetPin OutPin,dout : Pin(OutPin)=1 'initialize keypad rows
HC595 OutPin,RnC,0  'set all outputs to 0
SetPin InPin,intl,KP_int',pullup 'initialize keypad columns

Sub KP_Int
  SetPin InPin,off :SetPin InPin,Din',PULLUP 'disable inerrupt while reading
  t=Timer
  Pause 1 'key de-bounce time, adjust to suit your keypad
  Local integer R, C

  For R=0 To Rows-1  'seek the active row
    HC595 OutPin,RnC,15-(1<<R)
    If Pin(InPin)=0 Then Exit For
  Next

  For C=0 To Cols-1  'seek the active column in the active row
    HC595 OutPin,RnC, 2^RnC-1-(1<<C+4)-(1<<R)
    If Pin(InPin)=0 Then Exit For
  Next

  HC595 OutPin,RnC,0 'Prepare for next press, set all pins low
  If R<Rows And C<Cols Then Key=R*4+C
  SetPin InPin,intl,KP_int',pullup 'restore interrupt
End Sub

Do
  If Key>-1 And Key<Rows*Cols Then
    Print "Key";Key, map$(key), Timer-t;" mS"
    Key = -1
  EndIf
Loop

Sub HC595 O.Pin As integer, N.out As integer, Dat As integer
'        Data output Pin, number of Rows+Cols, Word to output
  Pin(O.Pin)=1  'ensure correct polarity for Bitstream
  N.out = N.out - 1 'array uses base 0
  Local n
  Local float B(N.out)
  For n=0 To N.out 'prepare data timing array
    B(n)=(11-(Dat>>(N.out-n) And 1)*6)/1000 'low data pulses, 20uS=0 ,10uS=1
  Next
  For n=0 To N.out :Pulse O.Pin,B(n) :Next 'Send the data
  Pin(O.Pin)=1' : Pause 0.05 ' >50uS high = latch clock
End Sub

End