Chief Delphi - I2C with Arduino

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I2C with Arduino

I'm having some trouble communicating with the Arduino over I2C.

We're planning to use it for LED strips, since almost all our PWM slots are taken. But most examples I find online use Java, not Python. Is there any way to easily write a string over I2C? For example, writing something like "rgb,10,0,255" would turn on the RGB strip.

Re: I2C with Arduino

Quote:

Originally Posted by codetheweb (Post 1540744)

Can you post a link to java code that you think will solve your problem?

Re: I2C with Arduino

Here.

Quote:

Originally Posted by Rakusan2 (Post 1441280)

My team got the Arduino communicating with the roborio over I2C using the following code on the roborio

Code:

static I2C Wire = new I2C(Port.kOnboard, 4);



if (Global.driver.Buttons.Back.changedDown) {

        String WriteString = "go";

        char[] CharArray = WriteString.toCharArray();

        byte[] WriteData = new byte[CharArray.length];

        for (int i = 0; i < CharArray.length; i++) {

                WriteData[i] = (byte) CharArray[i];

        }

        Wire.transaction(WriteData, WriteData.length, null, 0);

}

And this code on the Arduino

Code:

#include <Wire.h>



void setup()

{

  pinMode (13, OUTPUT);

  Wire.begin(4);                // join i2c bus with address #4

  Wire.onReceive(receiveEvent); // register event

}



void loop()

{

  delay(100);

}



// function that executes whenever data is received from master

// this function is registered as an event, see setup()

void receiveEvent(int howMany)

{

  String LED = "";

 

  while ( Wire.available() > 0 )

  {

    char n=(char)Wire.read();

    if(((int)n)>((int)(' ')))

   LED += n; 

  }

  

  if (LED == "go") 

  {

    

    digitalWrite (13, HIGH);

  

    

  }

}

Re: I2C with Arduino

First part, should be pretty straightforward.

Code:

wire = wpilib.I2C(wpilib.I2C.Port.kOnBoard, 4)

Second part -- I admit the docs aren't super clear here, but it wants you to pass it a list of things that can be converted to bytes... so either integers or a bytestring.

Code:

wire.transaction(b'go', 0)

I'm pretty sure that'll work.

It's weird that the java code isn't trying to receive any data (maybe writeBulk is more appropriate?).

Re: I2C with Arduino

Thanks, works great! In case anyone else stumbles across this, here's the code I used:

Code:

import wpilib



class MyRobot(wpilib.IterativeRobot):



    def robotInit(self):

        self.stick = wpilib.Joystick(0)

        self.arduino = wpilib.I2C(wpilib.I2C.Port.kOnboard, 4)



    def teleopPeriodic(self):

        if (self.stick.getTrigger()):

            try:

                data = self.arduino.transaction(b'go', 0)

            except:

                pass

        else:

            try:

                data = self.arduino.transaction(b'stop', 0)

            except:

                pass



if __name__ == "__main__":

    wpilib.run(MyRobot)

And

Code:

#include <Wire.h>



void setup()

{

  Wire.begin(4);                // join i2c bus with address #4

  Wire.onReceive(receiveEvent); // register event

  Serial.begin(9600);

  Serial.print("Hello");



}



void loop()

{

  delay(100);

}



void receiveEvent(int howMany)

{

  String rxString = "";

 

  while ( Wire.available() > 0 )

  {

    char n=(char)Wire.read();

    if(((int)n)>((int)(' ')))

    rxString += n; 

  }



  Serial.print(rxString);

}

Re: I2C with Arduino

Awesome, I like how much shorter it is than the Java version: