Serial communication issues

Hi!

I'm trying to create an .m-file that can both send transmit and receive data from an Arduino Uno. The Arduino is set to echo any incoming signal.

When I'm using the mttool I get the correct values, in eg if I send 1 the received data is 1. But the things is when I try to do this with an m-file I get:

Warning: A timeout occurred before the Terminator was reached.

This is the code I'm using:

% Find a serial port object.
obj1 = instrfind('Type', 'serial', 'Port', '/dev/tty.usbmodemfd131', 'Tag', '');

% Create the serial port object if it does not exist
% otherwise use the object that was found.
if isempty(obj1)
    obj1 = serial('/dev/tty.usbmodemfd131','BaudRate', 9600, 'StopBits', 1);

else
    fclose(obj1);
    obj1 = obj1(1)
end

% Connect to instrument object, obj1.

fopen(obj1);

% Communicating with instrument object, obj1.
data1 = query(obj1, '1');
fclose(obj1);

I'm using an macbook btw..

Answer 1

[bym]

It's possible that mttool (whatever that is) is adding a termination character to the communication packet that Matlab is not. You might try spying on the port to see the packet structure to determine if that is the case. Or you could try:

data1 = query(obj1,'1\n');

[Walter Roberson]

I agree, termination issues would be the first place to look. The default terminator for serial objects might not be the same as what the Arduino needs (my recollection of previous Arduino threads is that this *is* an issue.)

Answer 2

[Olof Hansson]

tmtool not mttool, my bad.

Thanks for the suggestion. Unfortunately it did not solve my issues.

This is the setup I'm using. http://farm8.staticflickr.com/7159/6575959063_28eb0b9b41_b.jpg

So the serial communication works. From the session log tab one could snap the code for the very same sequence.

http://farm8.staticflickr.com/7011/6575978053_b7936edbf5_b.jpg

Thanks for your help guys!

[Walter Roberson]

Please get(obj1,'Terminator) to check. The %s\n is not sufficient to establish that Linefeed is being used: see http://www.mathworks.com/help/techdoc/matlab_external/terminator.html