How to use I2C functionality about remote-wiring

[Thejayman77]

I too am having an issue working with I2C/Remote-Arduino. I'm using an HDC100x temp sensor, and can read the Device ID (0x1000) using the native Arduino Wire library commands. However, when using the I2C event/callback functionality, I receive no response except for 0s.

To verify, I am having the callback function called, but no data is received using the DataReader variable.

I'm not sure if I'm doing it correctly, but here's the code I'm using:

arduino.pinMode(20, PinMode.I2C);
arduino.pinMode(21, PinMode.I2C);
arduino.I2c.enable();
arduino.I2c.I2cReplyEvent += getData;

arduino.I2c.beginTransmission(0x40);
arduino.I2c.write(0xff);
arduino.I2c.endTransmission();
arduino.I2c.requestFrom(0x40, 2);

private void getData(byte myAdd, byte myReg, Windows.Storage.Streams.DataReader myRep)
        {
            var ignored = Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
                textBox.Text = "Received: ";
                byte[] myVals = new byte[2];
                myRep.ReadBytes(myVals);
                foreach (byte i in myVals)
                {
                    textBox.Text += i;
                }
            });
        }

I've tried putting the data gathering inside and out of async functions without any change. I've also tried changing how the data is gotten from the myRep variable. I'm guessing I might be missing something fundamental, but maybe someone can offer some additional guidance.

[Thejayman77]

OK, got it working with the UNO. Perhaps I was having problems because I was trying to use the DUE and it's not quite fully supported? Not sure, but I still receive zeros on the Due, and the Uno is still a little finicky, though I can receive the correct response.

I had to issue two requestFrom statements, but also needed to request more bytes than I actually needed to read out the register from my device. For instance, when checking the ID, I only actually needed to request 2 bytes to verify reading was correct. Instead, I used a request for 18 bytes, twice. This allowed me to click a button, and get the correct response from the register that had the device ID. Without putting two identical requestFrom statements, I had to click the read button (That I programmed) multiple times before the correct response was obtained.

I went back and tried this with the Due, but it still only gave me zeros. I also tried on the SDA/SCL(1) pins on the Due, with no difference in outcome.

So, perhaps a timing issue, or maybe something else, but there's at least one way to get it to work (On the Uno). I think the Due Firmata might be problematic. Other functionality does work on the Due, but not the I2C from what I can see.

Hope this makes sense. Let me know if you still have problems.

[zfields]

Ideally you would use remote-wiring to create a virtual instance of your Arduino and send the I2C transactions in the standard Arduino format.

[Thejayman77]

I wasn’t aware of an remote-wiring instance version of Wire.read. I believe it used to show up, but no longer does.

For example, if I have an instance of remote-wiring called ‘arduino’, I can’t make a call to arduino.I2c.read() as I would make a call to wire.read() in Arduino.

Is there something similar? Are you guys aware that the callback doesn’t specify the register upon reading it after a response? Or am I just doing something wrong?

I even tried using a firmata call (Using .getRegister()), but still don’t see anything in the reg variable except for 0.

From: Zachary J. Fields [mailto:[email protected]]
Sent: Tuesday, May 17, 2016 9:00 PM
To: ms-iot/remote-wiring [email protected]
Cc: Jason A. Hegedus [email protected]; Mention [email protected]
Subject: Re: [ms-iot/remote-wiring] How to use I2C functionality (#93)

Ideally you would use remote-wiring to create a virtual instance of your Arduino and send the I2C transactions in the standard Arduino format.

—
You are receiving this because you were mentioned.
Reply to this email directly or view it on GitHubhttps://github.com//issues/93#issuecomment-219897607

[zfields]

@turkycat wrote the i2c functionality, so he is the best to answer your question. I'm on vacation, but if we don't hear from him before I get back, then I'll try and work out an answer for you.

[mcinnes01]

Yes this is pretty much where I'm coming undone, the only details or examples I've seen reference methods that either no longer exist or are used in a different way. I did find some fairly helpful bit here: https://channel9.msdn.com/Events/Ignite/Australia-2015/MOB222 and here: https://github.com/mitchdenny/msftignite2015au-mob222.

[IoTGirl]

Hi Jesse,
Could you please take a look at this issue?
Sincerely,
IoTGirl

[lucora]

I've solved in this mode (I don't know how) :

// in my case I used a buffer with 16 bytes array

   private async void ButtonI2CReceive_OnClick(object sender, RoutedEventArgs e)
    {
        arduino.I2c.enable();
        arduino.I2c.requestFrom(9, 16);
        await Task.Delay(10);
        arduino.I2c.requestFrom(9, 16);
    }

I receive only one event on trigger it.

[saraclay]

If this issue is still relevant, please file this at: https://github.com/MicrosoftDocs/windows-iotcore-docs