MATLAB Examples

Push Button Control with 74HC165 Shift Register

This example shows how to use the MATLAB® Support Package for Arduino® Hardware to collect large number of push button states with a 74HC165 8-bit paralle-in-serial-out shift register. This example uses four push buttons.

Contents

Hardware Requirements

  • Arduino board
  • Four push buttons
  • 74HC165 8-bit parallel-in-serial-out shift register
  • Four 10K ohm resistors
  • Breadboard and wires

Hardware Setup

Connect push buttons and 74HC165 shift registers to Arduino hardware:

  • Connect Vcc pin on 74HC165 to 5V pin on Arduino hardware.
  • Connect GND pin on 74HC165 to GND pin on Arduino hardware.
  • Connect Q7 pin on 74HC165 to digital pin 11 on Arduino hardware.
  • Connect CP pin on 74HC165 to digital pin 8 on Arduino hardware.
  • Connect PL pin on 74HC165 to digital pin 9 on Arduino hardware.
  • Connect CE pin on 74HC165 to digital pin 10 on Arduino hardware.
  • Connect a push button to pin D0, D4, D5 and D7 on 74HC165 with a pull down resistor to GND as shown below.
  • Connect pin D1, D2, D3 and D6 on 74HC165 to GND pin on Arduino hardware.

Create Shift Register Object

Create an arduino object, and include the ShiftRegister library.

   a = arduino('COM7', 'Uno', 'Libraries', 'ShiftRegister')
a = 

  arduino with properties:

                    Port: 'COM7'
                   Board: 'Uno'
           AvailablePins: {'D2-D13', 'A0-A5'}
               Libraries: {'ShiftRegister'}

Create shift register object, specifying the connected data pin, clock pin, load pin, and clock enable pin.

   dataPin = 'D11';
   clockPin = 'D8';
   loadPin = 'D9';
   clockEnablePin = 'D10';
   register = shiftRegister(a, '74HC165', dataPin, clockPin, loadPin, clockEnablePin)
register = 

  shiftRegister with properties:

           Model: '74HC165'      
         DataPin: 'D11'          
        ClockPin: 'D8'           
         LoadPin: 'D9'           
  ClockEnablePin: 'D10'          

Read Push Button States

Monitor the states of the four push buttons, and print out a message if at least one button is pressed,

    states = read(register, 8);
    pressedButtons = find(states == 1)-1;
    if ~isempty(pressedButtons)
        bitsStr = num2str(pressedButtons, '%d ');
        disp(['Push button(s) connected to bit ', bitsStr, ' is pressed']);
    end
Push button(s) connected to bit 0 1 2 3 4 5 6 is pressed

Clean Up

When the connection is no longer needed, clear the shift register and arduino object.

  clear register a