MATLAB: Matlab Sending Arrays to Arduino with For loop

arduinoarrayserial communicationsinewave

Hello Matlab Users,

Right now I'm trying to send an array out of matlab to arduino. Below is my code. When i run this code, nothing seems to happen. Is this b/c of the for loop, or is there a different reason? Thanks for all the help.

    t = 0:1:40;
    A =500;
    f =500;
    fs = 8000;
    x = A*sin(2 * pi * f  / fs * t) + A;
    plot(t, x);
    arduinocom = serial('COM4', 'BaudRate', 9600);
    fopen(arduinocom);
        for i = 1:length(x)
        a = x(i);
    fprintf(arduinocom, '%d', a);
    end
    fclose(arduinocom);

Best Answer

You are not putting in any delimiters between the numbers, so [12 34 567] would be sent as '1234567'

For efficiency you should consider not using a loop and instead using

fprintf(arduinocom, '%d ', x)        %entire variable

However if the vector to be sent is large that could overflow the serial output buffer. It is possible to increase the size of the buffer: https://www.mathworks.com/help/matlab/matlab_external/outputbuffersize.html

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MATLAB: How to send data from MATLAB to Arduino an

I suppose you could do it through serial connections. If you have a serial port (or a serial to USB adapter and driver) you can create and open a COM object in MatLab to communicate with the Arduino board (usually arduino terminals D0 and D1 are serial TX/RX).

The code would be something like:

 arduinoCom = serial('COM3','BaudRate',9600 . . . );  % insert your serial
                                                           %properties here
 sendData = 5;
 fopen(arduinoCom);
 fprintf(arduinoCom,'%i',sendData); %this will send 5 to the arduino
 fscanf(arduinoCom)    %this will read response
                       %or use BytesAvailableFcn property of serial

You will have to look into using the correct terminators and do a bit of configuration with that. Let me know if this makes sense. Usually terminators are something like a linefeed / carriage return or an symbol (*, $, etc.)

MATLAB: Arduino i2c communication

Notice that you are only communicating to one arduino, and you connect to only one i2c bus, and that you read from the same A0 register on that one bus.

Your diagram appears to show the kind of configuration you would use for setting a voltage on one arduino and reading it on a different arduino... except that you do not show any i2c devices.

Ah...

dev = i2cdev(arduinoObj,'0x02'); %Create a device object.

The i2cdev() call is only for Raspberry Pi hardware. You would need https://www.mathworks.com/help/supportpkg/arduinoio/i2c-devices.html

dev = device(arduinobj, 'I2CAddress', '0x20');

Then look at

L00 = readVoltage(a,'A0'); % readvoltage at master

Notice this was a call to read from an analog voltage pin connected directly to the Arduino, not from the I2C device. In particular it asks to read from the A0 pin, which is the one that on your left device is connected to the purple (center) wire of your left potentometer, which is the voltage reading.

On the right hand pot, the voltage reading is connected to A0 of the second arduino.

You can skip working with I2C at all (at least for the purpose of the readings) if you connect the second arduino to the host and use a second arduino object.

You can also skip working with I2C at all if you configure the second arduino to read from its A0 and write the values to either A5 or A6, and have the first arduino read from that pin with a readVoltage .

It is not obvious to me that working with I2C is adding anything of value to your situation.

Best Answer

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MATLAB: Arduino i2c communication

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