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From: Chen Zhao on 25 Jun 2010 13:02
Hi,

I'm making a GUI that displays a information according to the data read from a serial port. The device outputs data every 5 seconds, so the GUI updates information every 5 seconds. I want to include a uicontrol toggle button that will start/stop receiving data. When I use fread (serial), the program waits until 64 bytes of data is received; this means it could be waiting for up to 5 seconds. During this time, none of the callbacks from any of the uicontrols work, until fread gets its 64 bytes. Is there a way I can get around this so that the callbacks work instantly, even when fread is waiting for data?

Here's a part of my code:

function out = sread()
delete(instrfind);
s = serial('COM1');
set(s,'BaudRate',9600);
fopen(s);
fprintf(s,'*IDN?');
out = fread(s,64); % this is where the program waits
fclose(s);
delete(s);
end

function button_callback(varargin)
state = get(button(1),'Value');
while state == get(button(1),'Max')
state = get(button(1),'Value');
pause(0.01);
set(button(1),'str','Stop');
if state == get(button(1),'Min')
break;
end
read(); % this function includes sread() and also updates GUI
end
set(button(1),'str','Start');
end

Thanks
-Chen
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