How can I read the button state of a joystick (ARD-358) using Arduino with Simulink?

I'm using Arduino MEGA 2560 with Simulink through the Simulink Support Package for Arduino Hardware and a joystick ARD-358

I have a problem when reading the state of the button of my joystick with the block Digital Input in Simulink. It does not read the digital signal, I always get the same value (0) wether I'm pressing the button or not.

This does not happen when using the following code in Arduino (the software).

int buttonPin = 53;
int buttonState = 0;

void setup() {
  Serial.begin(9600);
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  buttonState = digitalRead(buttonPin);
  Serial.print(" | Button: ");
  Serial.println(buttonState);

  delay(100);
}

With this code I do get an accurate lecture, so we can rule out hardware damage.

The only difference I see between the Simulink diagram and the Arduino code is the section void setup, in which the pinMode is defined. In the Command Window in MATLAB I can use a similar command, configurePin, but I do not know how to use it in simulink.

I'd very much appreciate your help.

Answer 1

[Arun Kumar]

Hi,

The only difference between your arduino sketch and the generated code is the the pin configuration. With arduino sketch, the pin is configured as INPUT_PULLUP which will enable the internal pullup of this pin. But with Simulink, the default behaviour of input pin is floating. I am guessing this is the reason for the observed behaviour.

Workaround:

1. External pullup resistor: You can connect an external pullup resistor to the input pin. Refer this wiki page for more details https://en.wikipedia.org/wiki/Pull-up_resistor

2. Modify Source file: Alternatively you can modify the Simulink source file to enable input pullup by default. For that do the following:

• In MATLAB command line type:

edit(fullfile(codertarget.arduinobase.internal.getSpPkgRootDir,'..','arduinobase','src','MW_arduino_digitalio.cpp'))

• MW_arduino_digitalio file will open the the editor. In this file change the line pinMode(pin, INPUT) to pinMode(pin, INPUT_PULLUP) inside the function digitalIOSetup

Hope this helps.

Cheers!