Beginner
10 min

Streamline the operation of complex systems with MC74HC165A and ATmega1284

Streamline your control: 16 buttons, 1 masterpiece

4x4 Key Click with EasyAVR v7

Published Oct 17, 2023

Click board™

4x4 Key Click

Dev Board

EasyAVR v7

Compiler

NECTO Studio

MCU

ATmega1284

Maximize space and functionality by choosing our 16-in-1 button integration solution for your control needs

A

A

Hardware Overview

How does it work?

4x4 Key Click is based on 16 buttons with debounce circuits and two MC74HC165A, 8-bit parallel-in/serial-out shift registers from ON Semiconductor. The rightmost column of the keyboard is marked with letters from A to D, while the other 12 buttons are marked like a telephone keypad, so it is easy to implement this 4x4 Click board to any design. The 16-button output lines go straight to the parallel data inputs of the two shift registers connected in a serial (daisy) chain, thus

occupying fewer pins on the host MCU. The shift registers allow you to press all 16 buttons simultaneously, and each will be registered. The 4X4 Click board uses an SPI serial interface to communicate with the host MCU over the mikroBUS™ socket. In this case, the SPI interface saves as many IO pins of the MCU as possible from 16 buttons using shift registers. The Clock Enable pins of the shift registers are not user-configurable and are tied LOW; thus, shift registers are always

enabled. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

4x4 Key Click hardware overview image

Features overview

Development board

EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more

efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)

connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyAVR v7 horizontal image

Microcontroller Overview

MCU Card / MCU

ATmega1284

Architecture

AVR

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

16384

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
PA5
CS
SPI Clock
PB7
SCK
SPI Data OUT
PB6
MISO
SPI Data IN
PB5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

4x4 Key Click Schematic schematic

Step by step

Project assembly

EasyAVR v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.

EasyAVR v7 front image hardware assembly
Buck 22 Click front image hardware assembly
MCU DIP 40 hardware assembly
EasyAVR v7 MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output via UART Mode

1. Once the code example is loaded, pressing the "FLASH" button initiates the build process, and programs it on the created setup.

2. After the programming is completed, click on the Tools icon in the upper-right panel, and select the UART Terminal.

3. After opening the UART Terminal tab, first check the baud rate setting in the Options menu (default is 115200). If this parameter is correct, activate the terminal by clicking the "CONNECT" button.

4. Now terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART_Application_Output

Software Support

Library Description

This library contains API for 4x4 Key Click driver.

Key functions:

  • c4x4key_get_data - Get 16-bit data function.

  • c4x4key_get_btn_position - Get position pressed button function.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * \file 
 * \brief 4x4Key Click example
 * 
 * # Description
 * The library covers all the necessary functions to control the 4x4 Key Click.
 * 4x4 Key click communicates with the target board via SPI interface. 
 * This library contains drivers for reading data from a sensor and get 
 * the position of the pressed button.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Configuring clicks and log objects.
 * 
 * ## Application Task  
 * This is a example which demonstrates the use of 4x4 Key Click board.
 * Detects and logs whether any of the buttons is pressed.
 * Results are being sent to the Usart Terminal
 * where you can track their changes.
 * All data logs on usb uart when the button is triggered.
 * 
 * \author Nenad Filipovic
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "c4x4key.h"

// ------------------------------------------------------------------ VARIABLES

static c4x4key_t c4x4key;
static log_t logger;

static uint16_t btn_data_old;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    c4x4key_cfg_t cfg;

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, "---- Application Init ----" );

    //  Click initialization.

    c4x4key_cfg_setup( &cfg );
    C4X4KEY_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    c4x4key_init( &c4x4key, &cfg );
    
    btn_data_old = 0;
    
    log_printf( &logger, "   4x4 Key Click\r\n" );
    log_printf( &logger, "--------------------\r\n" );
    log_printf( &logger, "  Press any button\r\n" );
    log_printf( &logger, "--------------------\r\n" );
}

void application_task ( void )
{
    uint16_t btn_data;
    
    btn_data = c4x4key_get_data( &c4x4key );

    if ( btn_data_old != btn_data )
    {
        if ( btn_data == C4X4KEY_BUTTON_0 )
        {
            log_printf( &logger, "         0\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_1 )
        {
            log_printf( &logger, "         1\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_2 )
        {
            log_printf( &logger, "         2\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_3 )
        {
            log_printf( &logger, "         3\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_4 )
        {
            log_printf( &logger, "         4\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_5 )
        {
            log_printf( &logger, "         5\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_6 )
        {
            log_printf( &logger, "         6\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_7 )
        {
            log_printf( &logger, "         7\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_8 )
        {
            log_printf( &logger, "         8\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_9 )
        {
            log_printf( &logger, "         9\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_A )
        {
            log_printf( &logger, "         A\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_B )
        {
            log_printf( &logger, "         B\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_C )
        {
            log_printf( &logger, "         C\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_D )
        {
            log_printf( &logger, "         D\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_STAR )
        {
            log_printf( &logger, "         *\r\n" );
        }
        
        if ( btn_data == C4X4KEY_BUTTON_HASH )
        {
            log_printf( &logger, "         #\r\n" );
        }

        btn_data_old = btn_data;
    }
    Delay_10ms();
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}


// ------------------------------------------------------------------------ END

Additional Support

Resources

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