Example Code for Arduino-Button Control LED

Hardware Preparation

• Hardware
  • DFRduino UNO x1
  • GPIO Shield for Arduino x1
  • Button module
  • LED module

Software Preparation

• Software
  • Arduino IDE Click to Download Arduino IDE from Arduino®

Wiring Diagram

Other Preparation Work

PCA9555DB IIC Address

• Config PCA9555 IIC Address with A0~A2 Jumper Caps (0x20~0x27)

Plug = 0
Unplug = 1

VCC Jumper Caps

There are two Jump caps, you can change the position of two caps for the different VCC power input. See the following schematic for details:

The middle pin is the shield VCC pin.
If you connect caps on the left side, VCC pins get power from the shield external port;
If you connect caps on the right side, VCC pins get power from the board 5V port;

This is suitable for some applications that require greater current.

Sample Code

In this section, we will use an Arduino library written by nicoverduin
Github Library. About Library installation.

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include "clsPCA9555.h"
#include "Wire.h"


PCA9555 ioport(0x20);

void setup()
{
  ioport.pinMode(8, OUTPUT); //Set GPIOs pinMode LED
  ioport.pinMode(15, INPUT);  //Button
}

void loop()
{
  if (ioport.digitalRead(ED15) == LOW) {
    ioport.digitalWrite(8, LOW);                  //Turn off Led
  }

  if (ioport.digitalRead(ED15) == HIGH) {
    ioport.digitalWrite(8, HIGH);                 //Turn on Led
  }

}

Additional Information

"D": represents digital signal
"A": represents analog signal

One of the biggest benefits of the I/O expansion shield is more power and GND pins, allowing you to connect more sensors.

* Green: digital signal
* Blue: analog signal
* Red: VCC
* Black: GND

• This is DFRobot's Gravity Interface. Digital and analog connections are easy to recognize and support most of DFRobot's I/O expansion shields and modules. Search "Gravity" in the DFRobot store to find compatible modules.