function [exectime, data] = ctrlcode(seg, data)switch seg, case 1,   % Read all buffered packets  temp = ttTryFetch('sensor_signal');  while ~isempty(temp),    y = temp;    temp = ttTryFetch('sensor_signal');  end      r = ttAnalogIn(1);    % Read reference value  P = data.K*(r-y);  D = data.ad*data.Dold + data.bd*(data.yold-y);  data.u = P + D;  data.Dold = D;  data.yold = y;  exectime = 0.0005; case 2,  msg.msg = data.u;  msg.type = 'control_signal';  ttSendMsg(1, msg, 80);    % Send 80 bits to node 1 (actuator)  exectime = -1; % finishedend