GUI SERIAL COMMUNICATION INTERRUPT FUNCTION

I want to run a serial communication with a device.

i want all incoming messages to be displayed automatically. don't want to press a special button for that.

i tried using the

handles.serPIC.BytesAvailableFcnCount = @MyInterruptFcn
...
...
...
function MyInterruptFcn(hObject, eventdata)
{code for the interrupt function}
end

but this has no result

Answer 1

[Walter Roberson]

handles.serPIC.BytesAvailableFcn = @MyInterruptFcn;
handles.serPIC.BytesAvailableFcnCount = 1;   %or as appropriate
fopen(handles.serPIC)

[Daniel]

here is the relevant part of my code:

handles.SerPIC.BytesAvailableFcn = @intcon1;
handles.SerPIC.BytesAvailableFcnMode = 'byte';  
handles.SerPIC.BytesAvailableFcnCount = 1;
 ... some code
function  intcon1(hObject, eventdata, handles)
persistent current_state
persistent L;
persistent i;
persistent DATA;
persistent recieved_checksum;
% current_state = 0;
    *this_input = fread(handles.SerPIC,1);*
    switch current_state
        case 0 % state 0  wait for HEADER_1
            L=0;
            i=0;
            DATA=0;
            recieved_checksum=0;
            if (this_input == 85)
                current_state = 1;  
            else 
                current_state = 0;
            end
        case 1 % state 1  wait for HEADER_2
            if (this_input == 51) %was 170
                current_state = 2;
                recieved_checksum = 136;
            elseif (this_input == 85)
                current_state = 1;
            else
                current_state = 0;
            end 
        case 2 % state 2  wait for message length
             MESSAGE_LENGTH = this_input;
             L=MESSAGE_LENGTH;
             i=1;
             current_state = 3;
             recieved_checksum = mod(recieved_checksum + this_input,255);
        case 3
%         if (s.BytesAvailable == MESSAGE_LENGTH)
            DATA(i) = this_input;
            recieved_checksum = mod(recieved_checksum + this_input,255);
            i=i+1;
            L = L - 1;
            if L > 0
                current_state = 3;
            else
                current_state = 4;
            end
        case 4
              recieved_checksum = recieved_checksum - this_input;
              if (recieved_checksum ==0)
                  set(handles.temp_read,'string',[num2str(DATA(1))])
                  set(handles.voltage_read,'string',[num2str(DATA(2))])
                  set(handles.current_read,'string',[num2str(DATA(3))])
                    current_state = 0;
              else
                  current_state = 0;
              end
    end
        guidata(hObject,handles)
end

i get an error message regarding the callback function: undefined variable handles or class handless.serPIC error... this_input = fread(handles.serPIC,1)

[Walter Roberson]

You function will not get passed "handles". Change to

function intcon1(hObject, eventdata)

and

this_input = fread(hObject,1);

[Daniel]

thanks. that problem is solved. i also changed current_state paramter to global so i can share data and initialize it.

now at the end of the code i posted, i want to write data to a textbox acording to the data i recieve. but this function doesnt recognize handle... "the name 'temp_read' is not an accessible property for an instance of class 'serial port object'

question: how can i write to a textbox from within my callback function. i dont understand where this callback function "lives"

[Walter Roberson]

handles.SerPIC.BytesAvailableFcn = @(src, event) intcon1(src, event, handles.TextBoxToWriteTo);

function intcon1(hObject, eventdata, handle_to_output_to)
  ....
  set(handle_to_output_to, 'String', ....)

The callback "lives" attached to the serial port object as a property that is a function handle. When MATLAB detects appropriate input, it will pause whatever else is happening, invoke the function handle, and when the invoked function returns, whatever was paused will be resumed. Any parent calling function will be buried in the guts of MATLAB. The situation is the same as with timers, I think (not completely sure.)

[Daniel]

thanks you its working

[Jeff King]

Thanks, this post was extremely helpful!