timer in a class question

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0 个投票

Hi all,

I have been searching for the problem with this for quite a while and I am just not seeing what the problem is. I have a class that runs a timer that reads values from some hardware and displays them on a GUI. I am having trouble with the timer. here is the relevant code:

classdef Controller < handle

    properties (Access = private)
        gui_h;      
        ControllerObj;
        positionTimer;
    end
    methods
        function this = Controller()           
            this.gui_h = guihandles(Controller_fig);                       
            this.ControllerObj = PI_GCS_Controller();
            this.positionTimer = timer('BusyMode','drop','ExecutionMode','fixedRate','Period',1,'TimerFcn',@this.positionTimerFcn);
            start(this.positionTimer);
        end
    methods (Access = private)
        function this = UpdatePositionAndVoltage(this)
            % reads from the hardware and displays to the GUI
        end
        function this = positionTimerFcn(this,src,event)
            this.UpdatePositionAndVoltage(this);    
        end
        end  % end of methods

end

If I run this with the call to UpdatePositionAndVoltage commented out, and just disp a string to the command line, it works fine. the timer triggers at once per second. if I try to call this.UpdatePositionAndVoltage(this) I get the error message "Error while evaluating TimerFcn for timer 'timer-1' Too many input arguments." If I change the definition of Update... to UpdatePositionAndVoltage(this,~) I then get the error message "Error while evaluating TimerFcn for timer 'timer-1' No appropriate method, property, or field Controller for class Controller."

which seems like it is at least making it into the Update function, but the "Controller" is not defined in there? I am just not seeing what the problem is. I also tried passing in "this" as a parameter in the timer definition, but that didn't work either.

any insight would be greatly appreciated!

thanks, mln