updatetime(Clock)

function updatetime(Clock)
persistent AMPM Clocksec Clockmin Clockhr changehr changemin changeampm

if Clock == 0; return; end
    
hGUI     = evalin('base','hGUI');
h        = guidata(hGUI);
Hrfield  = get(h.text15,'String');

if strcmp(Hrfield,'00')
    AMPM      = 'am';
    Clocksec  = 0;
    Clockmin  = 0;
    Clockhr   = 12;
    changemin = 1;
    changehr  = 1;
    changeampm= 1;
end

Clocksec = Clocksec + 1;
if Clocksec == 60
    Cm = get(h.text13,'String');
    Clockmin = str2double(Cm); 
    Clocksec = 0;
    Clockmin = Clockmin + 1;
    changemin = 1;
    if Clockmin == 60
        Ch = get(h.text15,'String');
        Clockhr   = str2double(Ch);
        Clockhr   = Clockhr + 1;
        Clockmin  = 0;
        changehr  = 1;
        if Clockhr == 13; Clockhr = 1; end
        if Clockhr == 12 && Clockmin == 0
            changeampm = 1;
            if strcmp(AMPM,'am')
                AMPM = 'pm';
            else
                AMPM = 'am';
            end
        end
    end
end


if changemin == 1; 
    Clockmins = num2str(Clockmin);
    if Clockmin < 10; Clockmins = ['0' Clockmins]; end
    set(h.text13,'String',Clockmins)
    changemin = 0;
end
if changehr == 1;
    Clockhrs = num2str(Clockhr);
    set(h.text15,'String',Clockhrs)
    changehr = 0;
end
if changeampm == 1;
    set(h.text11,'String',AMPM)
    changeampm = 0;
end