16-key matrix keyboard connected to PA27-PA24 and PB3-PB0 More...

Functions
void	Matrix_Init (void)
	Initialize matrix keyboard. More...

char	Matrix_InChar (void)

Detailed Description

16-key matrix keyboard connected to PA27-PA24 and PB3-PB0

Matrix scanned keyboard For more information see
Section 3.4 in https://users.ece.utexas.edu/~valvano/EE445L/ebook/index.htm

Author: Valvano

Warning: AS-IS

Date

July 29, 2026

Pins on the 16-key matrix keyboard
Pin	GPIO	Hardware
PA27	input	column 3 (keypad pin 4) using 10K pull-up
PA26	input	column 2 (keypad pin 3) using 10K pull-up
PB17	input	column 1 (keypad pin 2) using 10K pull-up
PA25	input	column 0 (keypad pin 1) using 10K pull-up
PB3	output	row 3 (keypad pin 8)
PB2	output	row 1 (keypad pin 7)
PB1	output	row 1 (keypad pin 6)
PB0	output	row 0 (keypad pin 5)

[1] [2] [3] [A]
[4] [5] [6] [B]
[7] [8] [9] [C]
[*] [0] [#] [D]
Pin1 . . . . . . . . Pin8
Pin 1 -> Column 0 (column starting with 1)
Pin 2 -> Column 1 (column starting with 2)
Pin 3 -> Column 2 (column starting with 3)
Pin 4 -> Column 3 (column starting with A)
Pin 5 -> Row 0 (row starting with 1)
Pin 6 -> Row 1 (row starting with 4)
Pin 7 -> Row 2 (row starting with 7)
Pin 8 -> Row 3 (row starting with *)

Function Documentation

◆ Matrix_InChar()

char Matrix_InChar ( void )

input ASCII character from keypad

Parameters

none

Returns: ASCII character of key touched

Note: spin if Fifo is empty

◆ Matrix_Init()

void Matrix_Init ( void )

Initialize matrix keyboard.

Initialization of Matrix keypad, 40 Hz SysTick interrupt