Python Tutorials – Lesson 15 – 4×4 Matrix Keypad Module using Raspberry Pi Pico

To control 4×4 Matrix Keypad Module using Raspberry Pi Pico

Required Components

1. 4×4 Matrix Keypad_1 no
2. Raspberry Pi Pico board_1 no
3. Data Cable_1 no
4. Connecting Wires_8 no

Circuit

Steps

1. Make sure the components are working properly.
2. 4×4 Matrix keypad 1 to 8 pins connected to GP1 to GP8 of Raspberry Pi Pico Board respectively.
3. Check the Python program.
4. Check the Electrical Circuit.
5. Run the Python program.

Python Program

from machine import Pin
import utime

# define PINs according to cabling
# following array matches 1,2,3,4 PINs from 4x4 Keypad Matrix
col_list=[1,2,3,4]
# following array matches 5,6,7,8 PINs from 4x4 Keypad Matrix
row_list=[5,6,7,8]

# set row pins to output and change array elements from
#    int to Pin objects, all set to high
for x in range(0,4):
    row_list[x]=Pin(row_list[x], Pin.OUT)
    row_list[x].value(1)

# set columns pins to input and change array elements 
#   from int to Pin objects. We'll read user input here
for x in range(0,4):
    col_list[x] = Pin(col_list[x], Pin.IN, Pin.PULL_UP)

# Create a map between keypad buttons and chars
key_map=[["D","#","0","*"],\
         ["C","9","8","7"],\
         ["B","6","5","4"],\
         ["A","3","2","1"]]

def Keypad4x4Read(cols,rows):
  for r in rows:
    r.value(0)
    result=[cols[0].value(),cols[1].value(),cols[2].value(),cols[3].value()]
    if min(result)==0:
      key=key_map[int(rows.index(r))][int(result.index(0))]
      r.value(1) # manages key keept pressed
      return(key)
    r.value(1)

# Start the main loop
print("--- Ready to get user inputs ---")
while True:
    key=Keypad4x4Read(col_list, row_list)
    if key != None:
      print("You pressed: "+key)
      utime.sleep(0.3) # gives user enoght time to release without having double inputs