Arduino MicroPython Keypad 4x4
This guide will show you how to use an Arduino with a 4x4 keypad and MicroPython. You will learn:
- How to connect a 4x4 keypad to the Arduino
- How to write a MicroPython script for the Arduino to check if a key is pressed on a 4x4 keypad
- How to write a MicroPython script to verify a password entered from a 4x4 keypad
Hardware Preparation
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables.
Additionally, some of these links are for products from our own brand, DIYables.
Overview of 4x4 Keypad
The 4x4 keypad includes 16 soft buttons organized in rows and columns, forming a grid. Each button is referred to as a key.
Pinout
A 4x4 keypad uses 8 pins, split into two types: rows and columns.
- 4 pins connect to the rows (R1, R2, R3, R4).
- 4 pins connect to the columns (C1, C2, C3, C4).
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Arduino MicroPython Code
from DIYables_MicroPython_Keypad import Keypad
import time
NUM_ROWS = 4
NUM_COLS = 4
# Constants for GPIO pins
ROW_PINS = ['D14', 'D15', 'D16', 'D17'] # The Arduino Giga WiFi pins connected to the row pins
COLUMN_PINS = ['D18', 'D19', 'D20', 'D21'] # The Arduino Giga WiFi pins connected to the column pins
# Keymap corresponds to the layout of the keypad 4x4
KEYMAP = ['1', '2', '3', 'A',
'4', '5', '6', 'B',
'7', '8', '9', 'C',
'*', '0', '#', 'D']
# Initialize the keypad
keypad = Keypad(KEYMAP, ROW_PINS, COLUMN_PINS, NUM_ROWS, NUM_COLS)
keypad.set_debounce_time(400) # 400ms, addjust it if it detects twice for single press
print("Arduino MicroPython - Keypad 4x4 example")
# Main loop to check for key presses
while True:
key = keypad.get_key()
if key:
print("Key pressed: ", key)
Detailed Instructions
Here’s instructions on how to run the above MicroPython code on Arduino with Thonny IDE:
- Make sure Thonny IDE is installed on your computer.
- Make sure MicroPython firmware is installed on your Arduino board.
- If you are new to Arduino with MicroPython, see the Getting Started with Arduino and MicroPython.
- Connect the 4x4 keypad to the Arduino as shown in the diagram.
- Connect the Arduino board to your computer with a USB cable.
- Open Thonny IDE and go to Tools Options.
- Under the Interpreter tab, select MicroPython (generic) from the dropdown menu.
- Select the COM port corresponding to your Arduino board (e.g., COM33 on Windows or /dev/ttyACM0 on Linux).
- Navigate to the Tools Manage packages on the Thonny IDE.
- Search “DIYables-MicroPython-Keypad”, then find the Keypad library created by DIYables.
- Click on DIYables-MicroPython-Keypad, then click Install button to install Keypad library.
- Copy the provided Arduino MicroPython code and paste it into Thonny's editor.
- Save the MicroPython code to your Arduino by:
- Clicking the Save button or pressing Ctrl+S.
- In the save dialog, choose MicroPython device and name the file main.py.
- Click the green Run button (or press F5) to execute the code.
- Press some keys on the 4x4 keypad.
- Check out the message in the Shell at the bottom of Thonny.
Shell x
>>> %Run -c $EDITOR_CONTENT
MPY: soft reboot
MPY: soft reboot
Arduino MicroPython - Keypad 4x4 example
Key pressed: 1
Key pressed: 2
Key pressed: 3
Key pressed: 4
Key pressed: 5
Key pressed: 6
Key pressed: A
Key pressed: B
Key pressed: C
Key pressed: *
Key pressed: #
MicroPython (generic) • Giga Virtual Comm Port in FS Mode @ COM33 ≡
If it doesn't work, check your wiring carefully. It's easy to make mistakes when connecting the Arduino to the 4x4 keypad.
Keypad and Password
A keypad is often used to type a password. Here, we use two special keys:
- A key to begin or re-enter the password, like the "*" key.
- A key to complete the password entry, like the "#" key.
The password will consist of other keys, except for the two special keys. When you press a key:
- If the key is neither "*" nor "#", include it in the password being typed.
- If the key is "#", verify if the typed password is correct. Then, reset the password.
- If the key is "*", reset the password.
Keypad - Password Code
"""
This Arduino MicroPython script was developed by newbiely.com
This Arduino MicroPython script is made available for public use without any restriction
For comprehensive instructions and wiring diagrams, please visit:
https://newbiely.com/tutorials/arduino-micropython/arduino-micropython-keypad-4x4
"""
from DIYables_MicroPython_Keypad import Keypad
import time
NUM_ROWS = 4
NUM_COLS = 4
# Constants for GPIO pins
ROW_PINS = ['D14', 'D15', 'D16', 'D17'] # The Arduino Giga WiFi pins connected to the row pins
COLUMN_PINS = ['D18', 'D19', 'D20', 'D21'] # The Arduino Giga WiFi pins connected to the column pins
# Keymap corresponds to the layout of the keypad 4x4
KEYMAP = ['1', '2', '3', 'A',
'4', '5', '6', 'B',
'7', '8', '9', 'C',
'*', '0', '#', 'D']
# Initialize the keypad
keypad = Keypad(KEYMAP, ROW_PINS, COLUMN_PINS, NUM_ROWS, NUM_COLS)
keypad.set_debounce_time(400) # 400ms, addjust it if it detects twice for single press
# Define the correct password
correct_password = "1234A"
input_password = ""
print("Arduino MicroPython - Keypad 4x4 password")
# Main loop
while True:
key = keypad.get_key()
if key:
print(key)
if key == '*':
input_password = "" # Clear input password
elif key == '#':
if input_password == correct_password:
print("Password is correct")
# DO YOUR WORK HERE
else:
print("Password is incorrect, try again")
input_password = "" # Clear input password
else:
input_password += key # Append new character to input password string
- Copy the above code and paste it to the Thonny IDE's editor.
- Save the script to your Arduino
- Type the keys "123" and then hit "#".
- Type the keys "1234A" and then hit "#".
- Check out the message in the Shell at the bottom of Thonny.
Shell x
>>> %Run -c $EDITOR_CONTENT
MPY: soft reboot
MPY: soft reboot
Arduino MicroPython - Keypad 4x4 password
1
2
3
#
Password is incorrect, try again
1
2
3
4
A
#
Password is correct
MicroPython (generic) • Giga Virtual Comm Port in FS Mode @ COM33 ≡