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Connect Matrix Keypad with PIC Controller Code

The mikroC PRO for PIC provides a library for working with 4x4 keypad. The library routines can also be used with 4x1, 4x2, or 4x3 keypad.

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Tags: #controller#keypad#matrix#pic
Ibrar Ayyub By Ibrar Ayyub
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At a glance

CategoryCommunication & Interfacing
IncludesCode
Reading time~3 min
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  1. External dependencies of Keypad Library
  2. Library Routines
  3. Keypad_Init
  4. Keypad_Key_Press
  5. Keypad_Key_Click
  6. Code Example
  7. Quick Solutions to Questions related to mikroC PRO for PIC Keypad Project:
  8. Related projects

Summary of Connect Matrix Keypad with PIC Controller Code

The mikroC PRO for PIC offers a library to interface with 4x4, 4x1, 4x2, or 4x3 keypads. It initializes ports and provides functions like Keypad_Init, Keypad_Key_Press, and Keypad_Key_Click to detect and process inputs. The example demonstrates converting key codes to ASCII and displaying them on an LCD while counting presses.

Parts used in the mikroC PRO for PIC Keypad Project:

  • 4x4 Keypad (or 4x1, 4x2, 4x3)
  • PIC Controller
  • LCD Display
  • Keypad Library
The mikroC PRO for PIC provides a library for working with 4x4 keypad. The library routines can also be used with 4x1, 4x2, or 4x3 keypad. For connections explanation see schematic at the bottom of this page.

External dependencies of Keypad Library

The following variable must be defined in all projects using Keypad Library: Description : Example :
extern sfr char keypadPort; Keypad Port. char keypadPort at PORTD;

Connect Matrix Keypad with PIC Controller CodeLibrary Routines

  • Keypad_Init
  • Keypad_Key_Press
  • Keypad_Key_Click

Keypad_Init

Prototype void Keypad_Init(void);
Returns Nothing.
Description Initializes port for working with keypad.
Requires Global variable :
  • keypadPort - Keypad port

must be defined before using this function.
Example
C source
// Keypad module connections
char keypadPort at PORTD;
// End of keypad module connections
...
Keypad_Init();

Keypad_Key_Press

Prototype char Keypad_Key_Press(void);
Returns The code of a pressed key (1..16).
If no key is pressed, returns 0.
Description Reads the key from keypad when key gets pressed.
Requires Port needs to be initialized for working with the Keypad library.
Example
Code listing (2)
char kp;
...
kp = Keypad_Key_Press();

Keypad_Key_Click

Prototype char Keypad_Key_Click(void);
Returns The code of a clicked key (1..16).
If no key is clicked, returns 0.
Description Call to Keypad_Key_Click is a blocking call: the function waits until some key is pressed and released. When released, the function returns 1 to 16, depending on the key. If more than one key is pressed simultaneously the function will wait until all pressed keys are released. After that the function will return the code of the first pressed key.
Requires Port needs to be initialized for working with the Keypad library.
Example
Code listing (3)
char kp;
...
kp = Keypad_Key_Click();

Connect Matrix Keypad with PIC Controller Code schematichCode Example

This is a simple example of using the Keypad Library. It supports keypads with 1..4 rows and 1..4 columns. The code being returned by Keypad_Key_Click() function is in range from 1..16. In this example, the code returned is transformed into ASCII codes [0..9,A..F] and displayed on Lcd. In addition, a small single-byte counter displays in the second Lcd row number of key presses.
For more detail: Connect Matrix Keypad with PIC Controller Code
  • What is the purpose of the Keypad_Init function?
    It initializes the port for working with the keypad.
  • How does Keypad_Key_Press behave when no key is pressed?
    It returns 0 if no key is pressed.
  • Can this library be used with keypads other than 4x4?
    Yes, it can also be used with 4x1, 4x2, or 4x3 keypads.
  • What happens if multiple keys are pressed simultaneously in Keypad_Key_Click?
    The function waits until all pressed keys are released before returning the code of the first pressed key.
  • What range of values does Keypad_Key_Click return?
    It returns a value from 1 to 16 depending on the key.
  • Which variable must be defined before using the Keypad library?
    The global variable keypadPort must be defined.
  • Does Keypad_Key_Click wait for a specific action?
    Yes, it is a blocking call that waits until a key is pressed and then released.
  • How are key codes transformed in the provided code example?
    The returned codes are transformed into ASCII codes [0..9,A..F] and displayed on the LCD.
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Ibrar Ayyub

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough...